Unified Plain-English Glossary: Economics & Trading

A master lookup reference for the 5-part economics & trading learning series. Roughly 600 entries spanning microeconomics, macroeconomics, market trading, and cross-cutting financial concepts.

How to use this glossary

Each entry follows this format:

### Term Name
**Domain**: [Micro / Macro / Trading / Multi]
**Symbol / formula** (if applicable): plain math notation
**Plain English**: 1–4 sentences in everyday language.
**Why it matters**: one sentence on practical relevance.
**Related**: [[other-term-1]], [[other-term-2]]
**See also**: pointer to a topical report section, when applicable.

Conventions:

• [[term-slug]] links are wiki-style references to other entries in this glossary. The slug is the term lowercased with hyphens replacing spaces (e.g., [[nash-equilibrium]] points to "Nash equilibrium"). Render or grep accordingly.
• Domain tag signals where you are most likely to meet the term. Multi means the same word is genuinely used across two or more of micro / macro / trading.
• "See also" points to the parallel reports (01-economic-theory-and-history.md, 02-macroeconomics-sota.md, 03-microeconomics-sota.md, 04-micro-macro-intermingling.md, 05-trading-theory-and-practice.md).
• Definitions favor the formal/academic form when popular usage diverges (e.g., "elasticity," "leverage," "alpha"). Contested or evolving terms are flagged in-line.
• For any contested or technical entry, the primary authoritative source is named in the entry. The full source inventory is at the end.

When a term has genuinely different meanings across domains, you will find separate sub-entries or an explicit note (see e.g. Beta, Premium (in trading), Leverage, Discount (in finance), Basis (futures − spot)).

Mathematical notation guide

A handful of symbols carry different meanings depending on the domain. Common ones you will meet in this glossary:

Ambiguity flags:

• π is the single biggest collision: inflation in macro, profit in micro.
• β means three different things across the three domains.
• r and R are often used interchangeably for "interest rate" or "return"; capital R sometimes denotes a gross return (1 + r).
• σ in academic econometrics is a population parameter; in trading desks "sigma" usually means realized or implied volatility, often annualized.

See the Greek letters & special symbols cheat sheet at the end of the document.

Microeconomics terms

Adverse selection

Domain: Micro Plain English: When one side of a transaction knows more about quality than the other, the better-informed side selects into deals that hurt the less-informed side. Classic Akerlof "lemons" market: only bad used cars get sold because owners of good ones won't accept the low average price. Why it matters: Explains market unraveling in insurance, credit, and labor markets and motivates screening, signaling, and mandates. Related: Asymmetric information, Moral hazard, Signaling (Spence), Screening, Lemons problem See also: covered in 03-microeconomics-sota.md §Information economics.

Anchoring

Domain: Micro (behavioral) Plain English: People's numerical judgments stick close to whatever number was suggested first, even if that number is irrelevant. Showing a high "list price" makes buyers willing to pay more for the discounted price. Why it matters: Pervasive in pricing, negotiation, valuation, and survey design. Related: Framing, Behavioral economics, Nudge

Asymmetric information

Domain: Micro Plain English: One party in a transaction knows materially more than the other. Generates Adverse selection (hidden information at the time of contracting) and Moral hazard (hidden action after contracting). Why it matters: Justifies large swaths of regulation, contracting design, and the existence of intermediaries. Related: Principal-agent problem, Signaling (Spence), Screening

Auction (English)

Domain: Micro Plain English: Ascending open-outcry auction. Price rises until only one bidder remains. Strategically dominant strategy: stay in until the price hits your private value. Why it matters: The most common auction format; useful baseline for revenue and efficiency comparisons. Related: Auction (Dutch), First-price auction, Second-price auction, Revenue equivalence theorem

Auction (Dutch)

Domain: Micro Plain English: Descending price auction. Auctioneer starts high and lowers the price until a bidder accepts. Strategically equivalent (under standard assumptions) to a First-price auction. Why it matters: Used for perishable goods (Dutch flower market) and some IPO mechanisms. Related: First-price auction, Revenue equivalence theorem

Auction (first-price sealed-bid)

Domain: Micro Plain English: All bidders submit one sealed bid; highest bidder wins and pays their own bid. Optimal strategy is to shade your bid below your value because you pay what you bid. Why it matters: Common in procurement and many real-world auctions; bid shading complicates revenue analysis. Related: Auction (Dutch), Winner's curse, Bayesian Nash equilibrium

Auction (second-price sealed-bid / Vickrey)

Domain: Micro Plain English: All bidders submit sealed bids; highest bidder wins but pays the second-highest bid. Truthful bidding (bid your true value) is a dominant strategy. Why it matters: Foundation of VCG mechanism (Vickrey-Clarke-Groves) and modern ad auction theory (though real ad auctions are usually generalized second-price or first-price now). Related: VCG mechanism (Vickrey-Clarke-Groves), Mechanism design, Revenue equivalence theorem

Average cost (AC)

Domain: Micro Symbol / formula: AC(q) = TC(q) / q Plain English: Total cost divided by quantity produced. Splits into average fixed cost and average variable cost; the U-shape of AC drives long-run firm size in textbook models. Why it matters: Together with Marginal cost (MC) determines competitive equilibrium output and entry/exit. Related: Marginal cost (MC), Economies of scale, Returns to scale

Bayesian Nash equilibrium

Domain: Micro (game theory) Plain English: A Nash equilibrium for games with incomplete information. Each player has a "type" drawn from a known distribution and plays a strategy that is best response given beliefs about other players' types. Why it matters: Workhorse solution concept for auctions, mechanism design, and signaling games. Related: Nash equilibrium, Mechanism design, Auction (first-price sealed-bid)

Bayesian persuasion

Domain: Micro (information economics) Plain English: A sender commits to an information-release rule (an experiment) before observing the state, in order to shift a receiver's posterior beliefs and thus their action. Kamenica–Gentzkow (2011). Why it matters: Formalizes how disclosure rules, ratings, and stress tests work as persuasion devices. Related: Information design, Signaling (Spence), Mechanism design See also: covered in 03-microeconomics-sota.md §Information design.

Behavioral economics

Domain: Micro Plain English: Economic analysis that incorporates psychologically realistic models of human decision-making — bounded rationality, biases, heuristics, social preferences — instead of strict expected-utility maximization. Why it matters: Reshaped policy (nudges, default enrollment), finance (limits-to-arbitrage), and consumer protection. Related: Prospect theory, Loss aversion, Nudge, Default effect, Hyperbolic discounting

BLP (Berry-Levinsohn-Pakes)

Domain: Micro (industrial organization) Plain English: An econometric method to estimate demand for differentiated products from market-level data (prices, shares, characteristics) while allowing for consumer heterogeneity and price endogeneity. Combines a random-coefficients logit demand system with instruments. Why it matters: Workhorse for modern empirical IO, merger simulation, and antitrust analysis. Related: Structural estimation, Instrumental variable (IV), Discrete choice See also: covered in 03-microeconomics-sota.md §Empirical IO.

Budget constraint

Domain: Micro Symbol / formula: p_x·x + p_y·y ≤ m Plain English: The set of consumption bundles a household can afford given prices and income. Drawn as a straight line in two-good diagrams. Why it matters: Half of the consumer's optimization problem; the other half is Preferences. Related: Indifference curve, Utility, Marginal rate of substitution (MRS)

Choice architecture

Domain: Micro (behavioral) Plain English: The design of the environment in which people make decisions — defaults, framing, ordering, the number of options. Choice architecture inevitably shapes outcomes, so the question is how to design it deliberately. Why it matters: Thaler–Sunstein "Nudge" framework; underlies retirement auto-enrollment, organ-donation defaults, and many digital UX patterns. Related: Nudge, Default effect, Framing

Coase theorem

Domain: Micro Plain English: If property rights are clearly assigned and bargaining is costless, parties will negotiate their way to an efficient outcome regardless of who initially holds the right. Real-world transaction costs are the reason this often fails. Why it matters: Theoretical underpinning for tradable permits (e.g., cap-and-trade) and a benchmark for thinking about externalities. Related: Externality, Property rights, Transaction costs

Cobb-Douglas production function

Domain: Micro / Macro Symbol / formula: Y = A · K^α · L^(1−α) Plain English: A production function in which output is a product of capital and labor raised to constant exponents that sum to one (constant returns to scale). Convenient because cost shares equal the exponents. Why it matters: Default specification in growth theory, calibrated DSGE models, and growth accounting. Related: Production function, Returns to scale, Solow growth model

Common-pool resource

Domain: Micro Plain English: A resource that is rival in consumption (one person's use reduces others') but hard to exclude people from using — fisheries, groundwater, common grazing land. Prone to overuse ("tragedy of the commons") absent governance. Why it matters: Elinor Ostrom's Nobel work showed local institutions often solve commons problems without privatization or top-down regulation. Related: Public good, Externality, Property rights

Common value (auction)

Domain: Micro Plain English: Auction setting where the item has the same underlying value to all bidders, but each bidder has noisy private information about that value (e.g., oil drilling rights). Contrast with private-value settings. Why it matters: Source of the Winner's curse. Related: Private value (auction), Winner's curse, Auction (first-price sealed-bid)

Compensating differentials

Domain: Micro (labor) Plain English: Wage premia paid for jobs with bad attributes (danger, night shifts, unpleasant conditions) to compensate workers for the disutility. In equilibrium, total compensation (wage + non-wage) is equalized for workers of equal skill. Why it matters: Empirical basis for the value of a statistical life and many labor-market hedonic studies. Related: Hedonic pricing, Human capital

Consumer surplus

Domain: Micro Symbol / formula: CS = ∫ (demand(p) − p*) dp from p* up Plain English: The difference between what consumers would have paid for a good and what they actually paid. Geometrically, the area below the demand curve and above the price line. Why it matters: Standard welfare measure for consumers in partial-equilibrium analysis. Related: Producer surplus, Deadweight loss, Welfare economics

Cross-price elasticity of demand

Domain: Micro Symbol / formula: ε_xy = (%ΔQ_x) / (%ΔP_y) Plain English: Percent change in quantity demanded of good x when the price of good y changes by 1%. Positive means substitutes (Pepsi/Coke), negative means complements (cars/gasoline). Why it matters: Core input to demand modeling, merger analysis, and antitrust market definition. Related: Elasticity (price of demand), Substitutes, Complements

Deadweight loss

Domain: Micro Plain English: The loss of total surplus (consumer + producer) caused by a market distortion such as a tax, monopoly pricing, or price ceiling. Trades that would have created mutual gains do not happen. Why it matters: Standard yardstick for the efficiency cost of policies. Related: Consumer surplus, Producer surplus, Tax incidence, Monopoly

Deferred acceptance (Gale-Shapley)

Domain: Micro (market design) Plain English: Two-sided matching algorithm that produces a stable matching: no pair would both prefer each other over their assigned partners. One side proposes; the other tentatively holds offers, accepting the best so far. Strategy-proof for the proposing side. Why it matters: Used in medical residency matches (NRMP), public-school choice (Boston, NYC), and many kidney-exchange variants. Related: Top trading cycles (TTC), Stable matching, Mechanism design See also: covered in 03-microeconomics-sota.md §Market design.

Default effect

Domain: Micro (behavioral) Plain English: When one option is preselected, far more people end up with it than would have actively chosen it. Defaults are sticky because of inertia, implicit endorsement, and loss aversion. Why it matters: Drove huge increases in 401(k) participation after auto-enrollment; explains cross-country organ-donation rate gaps. Related: Nudge, Status quo bias, Choice architecture

Difference-in-differences (DiD)

Domain: Micro (econometrics) Plain English: Quasi-experimental method that compares the change over time in a treated group to the change over time in a control group. Assumes parallel trends in the absence of treatment. Why it matters: One of the most widely used causal-inference designs in applied micro; recent literature (Goodman-Bacon, Callaway-Sant'Anna, de Chaisemartin) has reworked staggered-adoption versions. Related: Regression discontinuity (RD), Synthetic control, Parallel trends, Two-way fixed effects (TWFE) See also: covered in 03-microeconomics-sota.md §Causal inference.

Discrimination (taste-based vs statistical)

Domain: Micro (labor) Plain English: Taste-based (Becker): employers, coworkers, or customers have a "distaste" for a group and pay a premium to avoid them. Statistical: employers use group membership as a noisy proxy for productivity because individual signals are costly. Welfare and policy implications differ. Why it matters: Central distinction in the economics of inequality and in evaluating anti-discrimination policy. Related: Asymmetric information, Signaling (Spence), Human capital

Dominant strategy

Domain: Micro (game theory) Plain English: An action that gives a higher payoff than any other action, no matter what the other players do. Rare in the wild but powerful when it exists (e.g., truthful bidding in a Auction (second-price sealed-bid / Vickrey)). Why it matters: Mechanisms that are dominant-strategy incentive-compatible are extremely robust because participants don't need to model others. Related: Nash equilibrium, Mechanism design, Strategy-proof

Dynamic game

Domain: Micro (game theory) Plain English: A game with multiple stages where players move in sequence and can condition on the history of play. Solved by backward induction or Subgame perfection. Why it matters: Underlies bargaining, entry deterrence, repeated interactions, and most realistic strategic settings. Related: Subgame-perfect equilibrium, Repeated game, Folk theorem

Economies of scale

Domain: Micro Plain English: Average cost falls as output rises. Sources: spreading fixed costs, specialization, bulk purchasing, network effects. Diseconomies eventually appear (coordination costs). Why it matters: Drives concentration in industries with high fixed costs; rationale for natural monopoly regulation. Related: Returns to scale, Average cost (AC), Natural monopoly

Elasticity (price of demand)

Domain: Micro Symbol / formula: ε_d = (%ΔQ) / (%ΔP) = (dQ/dP)·(P/Q) Plain English: How responsive quantity demanded is to price. |ε|>1 elastic, |ε|<1 inelastic. Demand for luxuries is usually elastic, demand for necessities inelastic, addiction-related goods very inelastic. Why it matters: Determines tax incidence, optimal pricing, and pass-through. Related: Cross-price elasticity of demand, Income elasticity, Tax incidence

Elasticity (income)

Domain: Micro Symbol / formula: η = (%ΔQ)/(%ΔY) Plain English: How quantity demanded changes when income changes. >1 luxury, between 0 and 1 normal necessity, <0 inferior good. Why it matters: Used to classify goods and to forecast demand shifts with growth. Related: Normal good, Inferior good, Engel curve

Endowment effect

Domain: Micro (behavioral) Plain English: People demand more to give up an item they own than they would pay to acquire it. Driven by Loss aversion. Why it matters: Distorts willingness-to-pay/willingness-to-accept measures; relevant in property law, environmental valuation, and trading psychology. Related: Loss aversion, Prospect theory

Engel curve

Domain: Micro Plain English: Relationship between income and quantity demanded of a good, holding prices fixed. Slope reveals whether the good is normal, luxury, or inferior. Why it matters: Empirical workhorse for measuring inequality through consumption and for cost-of-living indices across income groups. Related: Elasticity (income), Normal good, Inferior good

Evolutionary game theory

Domain: Micro Plain English: Strategies are not chosen by rational players but evolve through replication and selection. The key solution concept is the evolutionarily stable strategy (ESS): once adopted by most of the population, no rare mutant can invade. Why it matters: Used in biology, in modeling cultural evolution, and in learning dynamics in games. Related: Nash equilibrium, Replicator dynamics

Externality

Domain: Micro Plain English: A cost or benefit imposed on a third party who is not part of the transaction. Pollution is a negative externality, vaccination a positive one. Markets generally over-produce goods with negative externalities and under-produce goods with positive ones. Why it matters: Primary economic rationale for regulation, Pigouvian tax, and tradable permits. Related: Pigouvian tax, Coase theorem, Social cost of carbon (SCC)

First-best vs second-best

Domain: Micro Plain English: First-best is the welfare-maximizing outcome with no constraints (perfect info, lump-sum transfers). Second-best is the best outcome achievable given real-world constraints (information frictions, distortionary taxes). Lipsey-Lancaster: removing one distortion can lower welfare if others remain. Why it matters: Disciplines naive "remove all market failures" prescriptions. Related: Pareto efficient, Mechanism design

Folk theorem

Domain: Micro (game theory) Plain English: In infinitely repeated games with patient enough players, almost any individually rational outcome can be sustained as an equilibrium via grim-trigger or other punishment strategies. Generates a multiplicity rather than a sharp prediction. Why it matters: Explains how cooperation can be sustained without contracts, but also limits the predictive power of repeated games. Related: Repeated game, Subgame-perfect equilibrium

Framing

Domain: Micro (behavioral) Plain English: How a choice is described (gain vs loss, percent vs absolute, default vs opt-in) changes the decision people make even when the underlying options are identical. Why it matters: Implication of Prospect theory; major lever in disclosure, marketing, and policy communication. Related: Prospect theory, Loss aversion, Anchoring

Game theory

Domain: Micro Plain English: Mathematical study of strategic interaction: how rational players choose actions when their payoffs depend on others' actions. Cooperative and non-cooperative branches. Why it matters: Foundational language for IO, auctions, contract theory, negotiation, and strategic finance. Related: Nash equilibrium, Dominant strategy, Mechanism design

Giffen good

Domain: Micro Plain English: A good whose quantity demanded rises when its price rises, because the income effect (a price increase makes you effectively poorer, and you consume more of this inferior staple) outweighs the substitution effect. Empirically rare; rice in poor Chinese provinces is one documented case (Jensen-Miller). Why it matters: Theoretical curiosity that demonstrates the law of demand can fail under specific conditions. Related: Inferior good, Veblen good, Income effect, Substitution effect

Gini coefficient

Domain: Micro (inequality) Symbol / formula: G = 1 − 2·∫ L(p) dp, where L is the Lorenz curve Plain English: Single number summary of inequality, between 0 (perfect equality) and 1 (one person has everything). U.S. household income Gini hovers around 0.40–0.49 depending on measure. Why it matters: Most-cited inequality statistic; insensitive to top-tail dynamics, which is why top-share measures are often used alongside. Related: Lorenz curve, Palma ratio, Top share (income / wealth)

Hedonic pricing

Domain: Micro Plain English: Method that decomposes the price of a heterogeneous good (house, car) into the prices of its underlying characteristics by regressing price on characteristics. Why it matters: Used in housing markets, BLS CPI quality adjustment, and labor Compensating differentials. Related: Compensating differentials, BLP (Berry-Levinsohn-Pakes)

Human capital

Domain: Micro / Macro Plain English: The stock of knowledge, skills, and health embodied in workers that raises their productivity. Investments include schooling, on-the-job training, and health care. Why it matters: Core construct in labor economics and endogenous growth theory. Related: Signaling (Spence), Returns to schooling, Endogenous growth

Hyperbolic discounting

Domain: Micro (behavioral) Plain English: People discount the near future more steeply than the distant future, generating preference reversals (you prefer $110 in 31 days to $100 in 30 days, but $100 today to $110 tomorrow). Quasi-hyperbolic (β-δ) is the workhorse functional form. Why it matters: Explains procrastination, undersaving, and demand for commitment devices. Related: Present bias, Time inconsistency, Commitment device

Income effect

Domain: Micro Plain English: The portion of a price change's effect on quantity demanded that comes from the change in real purchasing power. A price cut effectively makes you richer; how much more of the good you buy because of that is the income effect. Why it matters: Combined with Substitution effect via the Slutsky equation to decompose demand responses; underlies tax-incidence analysis. Related: Substitution effect, Slutsky equation, Giffen good

Indifference curve

Domain: Micro Plain English: The set of consumption bundles among which a consumer is indifferent. Standard assumptions: monotonic (more is better), convex (averages preferred to extremes). Slope at a point = the Marginal rate of substitution (MRS). Why it matters: Graphical workhorse of consumer theory. Related: Utility, Budget constraint, Marginal rate of substitution (MRS)

Industrial organization (IO)

Domain: Micro Plain English: The branch of microeconomics studying firm behavior, market structure, strategic interaction, regulation, and antitrust. Modern empirical IO uses structural estimation (BLP (Berry-Levinsohn-Pakes)) and reduced-form causal methods. Why it matters: Foundation for merger review, regulation, and platform policy. Related: BLP (Berry-Levinsohn-Pakes), Monopoly, Oligopoly See also: covered in 03-microeconomics-sota.md §Empirical IO.

Inferior good

Domain: Micro Plain English: A good whose quantity demanded falls as income rises (instant ramen, bus tickets in some markets). Income elasticity is negative. Why it matters: Necessary condition for a Giffen good; informs welfare analysis across income groups. Related: Normal good, Giffen good, Elasticity (income)

Information design

Domain: Micro Plain English: The design of information structures (what to disclose, when, with what noise) to influence agents' actions. Generalizes Bayesian persuasion to many receivers and to mechanism design with information control. Why it matters: Frames problems like stress test disclosure, school ratings, and recommendation systems. Related: Bayesian persuasion, Mechanism design, Signaling (Spence)

Instrumental variable (IV)

Domain: Micro (econometrics) Plain English: When you want the causal effect of X on Y but X is correlated with the error, find a variable Z that affects Y only through X and is unrelated to the unobservables. Use Z to isolate the exogenous variation in X. Why it matters: Workhorse for causal inference when randomized experiments aren't feasible (returns to schooling, supply-demand identification). Related: 2SLS (Two-stage least squares), LATE (local average treatment effect), Exclusion restriction, Regression discontinuity (RD) See also: covered in 03-microeconomics-sota.md §Causal inference.

Intention-to-treat (ITT)

Domain: Micro (econometrics) Plain English: In a randomized trial, the comparison of outcomes by initial assignment to treatment regardless of compliance. Conservative but unbiased; contrasts with Treatment-on-the-treated (TOT / ATT). Why it matters: Standard primary estimand in clinical trials and many development RCTs. Related: Random assignment / RCT, LATE (local average treatment effect), Treatment-on-the-treated (TOT / ATT)

Isoquant

Domain: Micro Plain English: Combinations of inputs (capital, labor) that produce the same level of output. The production-side analog of an Indifference curve. Why it matters: Used to derive cost minimization and input demand. Related: Production function, Marginal product

Kaldor-Hicks efficiency

Domain: Micro (welfare) Plain English: A change is Kaldor-Hicks efficient if the winners gain enough that they could, in principle, compensate the losers and still be better off (compensation need not actually occur). Weaker than Pareto efficient and the basis for cost-benefit analysis. Why it matters: Underlies most applied policy CBA; debated because compensation often doesn't happen. Related: Pareto efficient, Cost-benefit analysis

Kill zone (platform)

Domain: Micro / Multi Plain English: A market or product area near a dominant platform where startups attract less VC funding because investors fear the incumbent will copy or acquire-and-kill them. Why it matters: Increasingly cited rationale in antitrust scrutiny of Big Tech. Related: Platform economics, Network effects (direct vs indirect), Antitrust

LATE (local average treatment effect)

Domain: Micro (econometrics) Plain English: With a binary instrument, IV identifies the causal effect of treatment for the subgroup of "compliers" — people whose treatment status changes because of the instrument. Not the average effect across the whole population. Why it matters: Imbens-Angrist's clarification reshaped how IV results should be interpreted and generalized. Related: Instrumental variable (IV), Random assignment / RCT, External validity

Lemons problem

Domain: Micro Plain English: Akerlof's used-car model: buyers can't distinguish good cars from bad, so they offer an average price, sellers of good cars drop out, average quality falls, prices fall further, market unravels. Canonical case of Adverse selection. Why it matters: Motivates warranties, certification, and disclosure regulation. Related: Adverse selection, Signaling (Spence), Screening

Lorenz curve

Domain: Micro (inequality) Plain English: Plots cumulative share of income (y-axis) against cumulative share of population (x-axis), sorted from poorest to richest. Perfect equality is the 45° line; the further the curve sags below it, the more unequal the distribution. Why it matters: Visual foundation of the Gini coefficient. Related: Gini coefficient, Palma ratio, Top share (income / wealth)

Loss aversion

Domain: Micro (behavioral) Plain English: Losses hurt roughly twice as much as equivalent gains feel good (Kahneman-Tversky). Core ingredient of Prospect theory. Why it matters: Drives the Endowment effect, status-quo bias, the equity-premium puzzle, and behavior under risk. Related: Prospect theory, Endowment effect, Equity premium puzzle

Marginal cost (MC)

Domain: Micro Symbol / formula: MC(q) = dTC/dq Plain English: The cost of producing one more unit. Perfectly competitive firms produce where price equals marginal cost; monopolists produce where MR = MC. Why it matters: Central object in supply analysis, pricing, and welfare comparisons. Related: Marginal revenue (MR), Average cost (AC), Deadweight loss

Marginal product

Domain: Micro Symbol / formula: MP_L = ∂Y/∂L Plain English: Extra output produced by adding one more unit of an input, holding others fixed. Usually diminishing as the input rises. Why it matters: Equalizing marginal product per dollar across inputs is the firm's cost-minimization condition. Related: Production function, Isoquant, Diminishing returns

Marginal rate of substitution (MRS)

Domain: Micro Symbol / formula: MRS = MU_x / MU_y (absolute slope of indifference curve) Plain English: The rate at which a consumer is willing to swap good y for good x while staying equally happy. At an optimum, MRS equals the price ratio. Why it matters: Defines the consumer's optimal-choice condition. Related: Utility, Indifference curve, Budget constraint

Marginal revenue (MR)

Domain: Micro Plain English: Extra revenue from selling one more unit. For competitive firms MR = price. For monopolists MR < price because raising sales requires cutting price on all units. Why it matters: Combined with Marginal cost (MC) determines profit-maximizing output. Related: Marginal cost (MC), Monopoly, Elasticity (price of demand)

Marginal utility (MU)

Domain: Micro Symbol / formula: MU_x = ∂U/∂x Plain English: Extra utility from consuming one more unit of a good. Typically assumed positive and diminishing. Why it matters: Drives downward-sloping demand and many risk-aversion results. Related: Utility, Marginal rate of substitution (MRS), Diminishing returns

Market failure

Domain: Micro Plain English: A situation where a free market fails to produce a Pareto-efficient outcome. Standard sources: externalities, public goods, monopoly power, asymmetric information. A necessary but not sufficient condition for government intervention. Why it matters: Organizing concept for welfare economics and regulation. Related: Externality, Public good, Asymmetric information, Pareto efficient

Mechanism design

Domain: Micro Plain English: "Reverse game theory" — given a goal (efficiency, revenue, fairness), design the rules of the game so self-interested play produces that outcome. Auctions, matching markets, and voting are core applications. Why it matters: Hurwicz-Maskin-Myerson 2007 Nobel; the design discipline behind modern markets (spectrum auctions, kidney exchanges, ad auctions). Related: Revelation principle, VCG mechanism (Vickrey-Clarke-Groves), Deferred acceptance (Gale-Shapley), Strategy-proof See also: covered in 03-microeconomics-sota.md §Market design.

Mental accounting

Domain: Micro (behavioral) Plain English: People treat money differently depending on its source or labeled purpose (tax refund vs paycheck, gambling winnings vs savings). Violates fungibility. Why it matters: Explains many savings, spending, and budgeting patterns; relevant for designing transfer programs. Related: Behavioral economics, Framing

Mixed strategy

Domain: Micro (game theory) Plain English: A randomization over pure actions. In games with no pure-strategy Nash equilibrium (rock-paper-scissors, matching pennies), the equilibrium involves randomized play. Why it matters: Guarantees existence of equilibrium in finite games (Nash 1950). Related: Nash equilibrium, Dominant strategy

Monopolistic competition

Domain: Micro Plain English: Market with many firms, free entry, but differentiated products (restaurants, clothing brands). Each firm has some pricing power. In long-run equilibrium, firms earn zero economic profit but produce below minimum efficient scale. Why it matters: More realistic than perfect competition for consumer-facing markets; standard market structure in NK macro (Dixit-Stiglitz). Related: Dixit-Stiglitz aggregator, Product differentiation, Perfect competition

Monopoly

Domain: Micro Plain English: Single seller in a market, with significant pricing power. Produces where MR = MC, charges P > MC, generates Deadweight loss. Why it matters: Benchmark case for antitrust and regulation. Related: Monopolistic competition, Oligopoly, Natural monopoly, Deadweight loss

Monopsony

Domain: Micro (labor) Plain English: Single buyer (or dominant buyer) in a market — historically a coal-town employer, increasingly used to describe labor-market concentration even when many firms hire, because workers have limited outside options. Why it matters: Justifies minimum wages that don't reduce employment and motivates noncompete restrictions and antitrust attention to labor markets. Related: Monopoly, Minimum wage, Labor market concentration

Moral hazard

Domain: Micro Plain English: After a contract is signed, the better-informed party can take hidden actions that affect the outcome — borrowers taking more risk after getting a loan, drivers driving more recklessly after buying insurance. Contracting reduces this through monitoring, deductibles, or incentive pay. Why it matters: Pervasive in insurance, banking, and corporate governance; raised acutely after every banking bailout. Related: Adverse selection, Principal-agent problem, Asymmetric information

Multi-homing

Domain: Micro (platforms) Plain English: Users participating on multiple competing platforms simultaneously (riders use both Uber and Lyft, sellers list on both Amazon and Walmart). Reduces a platform's market power; single-homing strengthens it. Why it matters: Key parameter in platform competition and antitrust analysis. Related: Platform economics, Network effects (direct vs indirect), Switching costs

Nash equilibrium

Domain: Micro (game theory) Plain English: A profile of strategies such that no player can do better by unilaterally changing strategy, given the others' strategies. Doesn't require coordination or cooperation, just mutual best response. Why it matters: Most-used solution concept in non-cooperative game theory. Related: Dominant strategy, Mixed strategy, Bayesian Nash equilibrium, Subgame-perfect equilibrium

Network effects (direct vs indirect)

Domain: Micro / Multi Plain English: Direct: a good is more valuable when more people use it (telephone, social network). Indirect (cross-side, for two-sided markets): more users on side A make the platform more valuable to side B (more riders → more drivers → more riders). Why it matters: Drives winner-take-most dynamics, tipping, and lock-in. Related: Platform economics, Two-sided market, Multi-homing

Normal good

Domain: Micro Plain English: A good whose quantity demanded rises with income (income elasticity > 0). Most goods are normal; further split into necessities (0 < η < 1) and luxuries (η > 1). Why it matters: Basic classification for welfare and forecasting. Related: Inferior good, Luxury, Elasticity (income)

Nudge

Domain: Micro (behavioral) Plain English: A small, non-coercive change in choice architecture that predictably shifts behavior without removing options or changing economic incentives. Auto-enrollment in retirement plans is the classic case. Why it matters: Influential policy paradigm (UK Behavioural Insights Team, White House SBST); also criticized for paternalism and modest measured effects in recent meta-analyses. Related: Choice architecture, Default effect, Behavioral economics

Oligopoly

Domain: Micro Plain English: A market with a small number of strategically interacting firms. Standard models: Cournot (compete in quantities), Bertrand (compete in prices), Stackelberg (sequential), with collusion as the cooperative outcome. Why it matters: Most real concentrated markets are oligopolies; foundation for merger analysis. Related: Cournot competition, Bertrand competition, Collusion, Game theory

Opportunity cost

Domain: Micro Plain English: The value of the best forgone alternative. Eating dinner with a friend costs the price of the meal plus whatever you would otherwise have done with the time and money. Sunk costs aren't part of opportunity cost; future alternatives are. Why it matters: Foundational economic concept; the right benchmark for decisions and capital allocation. Related: Sunk cost, Economic profit

Optimal taxation (Ramsey)

Domain: Micro (public) Symbol / formula: Inverse elasticity rule (intuition): tax goods with low elasticity more. Plain English: To raise a given revenue with minimum deadweight loss, tax goods with inelastic demand more heavily. Ignores equity; equity considerations give the Mirrlees rule. Why it matters: Backbone of commodity taxation theory. Related: Mirrlees rule, Deadweight loss, Tax incidence

Optimal taxation (Mirrlees)

Domain: Micro (public) Plain English: Optimal income tax design when the government wants to redistribute but can't observe ability — only earnings. The optimal marginal tax schedule trades off redistribution against incentive distortions and depends on the distribution of ability and the elasticity of labor supply. Why it matters: 1996 Nobel; theoretical basis for modern optimal-tax work by Diamond-Saez and Piketty-Saez-Stantcheva. Related: Optimal taxation (Ramsey), EITC (Earned Income Tax Credit), Labor supply elasticity

Pareto efficient

Domain: Micro Plain English: An allocation such that no one can be made better off without making someone else worse off. A weak benchmark — many highly unequal allocations are Pareto efficient. Why it matters: First fundamental welfare theorem: competitive equilibria are Pareto efficient under standard conditions. Related: Kaldor-Hicks efficiency, Welfare theorems (first and second)

Pigouvian tax

Domain: Micro / Multi Plain English: A tax set equal to the marginal external cost of an activity, which internalizes the externality and restores efficient quantities. Carbon taxes are the leading example. Why it matters: Workhorse policy prescription for negative externalities. Related: Externality, Social cost of carbon (SCC), Carbon price

Platform economics

Domain: Micro / Multi Plain English: Economics of intermediaries that bring two or more groups together (Visa, Uber, Apple App Store). Pricing structure (which side subsidizes whom) matters as much as the price level. Studied by Rochet-Tirole, Armstrong, Weyl. Why it matters: Frames antitrust and regulation of digital platforms. Related: Two-sided market, Network effects (direct vs indirect), Kill zone (platform)

Preferences

Domain: Micro Plain English: A binary "at least as good as" ranking over consumption bundles. Standard assumptions: complete, transitive, and (often) continuous. With continuity, preferences can be represented by a Utility function. Why it matters: Primitive of consumer theory. Related: Utility, Indifference curve, Axioms of choice

Present bias

Domain: Micro (behavioral) Plain English: Overweighting the present moment relative to any future moment. The β in quasi-hyperbolic discounting (β·δ^t for t ≥ 1, 1 for t = 0). Generates time-inconsistent planning. Why it matters: Explains why people commit to gym memberships they don't use and why automatic savings work. Related: Hyperbolic discounting, Time inconsistency, Commitment device

Principal-agent problem

Domain: Micro Plain English: One party (principal) hires another (agent) to act on their behalf, but the agent's interests and information differ. Solved by carefully designed contracts trading off insurance and incentives. Why it matters: Frame for executive pay, sharecropping, regulation, and physician-patient relationships. Related: Moral hazard, Asymmetric information, Contract theory

Private value (auction)

Domain: Micro Plain English: Each bidder knows their own value for the item with certainty, and this value is independent of others'. Standard benchmark for auction theory. Why it matters: Setting in which classic results like Revenue equivalence theorem hold cleanly. Related: Common value (auction), Revenue equivalence theorem

Producer surplus

Domain: Micro Plain English: The difference between what producers actually receive and the minimum they would have accepted. Geometrically, the area above the supply curve and below the price line. Why it matters: Together with Consumer surplus measures total welfare in partial equilibrium. Related: Consumer surplus, Deadweight loss

Production function

Domain: Micro / Macro Symbol / formula: Y = F(K, L) or Y = A·F(K, L) Plain English: A mapping from inputs (capital, labor, often technology) to maximum output. Specific forms include Cobb-Douglas production function, CES, Leontief. Why it matters: Building block of producer theory and macro growth. Related: Returns to scale, Marginal product, Isoquant

Prospect theory

Domain: Micro (behavioral) Plain English: Descriptive theory of choice under risk (Kahneman-Tversky 1979). People evaluate gains and losses relative to a reference point, weigh losses about twice as heavily as gains (Loss aversion), and distort probabilities (overweighting small probabilities, underweighting large ones). Why it matters: Empirically dominates expected utility in many lab and field settings; explains the Equity premium puzzle and many insurance puzzles. Related: Loss aversion, Reference dependence, Probability weighting

Public good

Domain: Micro Plain English: Good that is non-rival (one person's use doesn't reduce another's) and non-excludable (hard to prevent free-riding) — national defense, knowledge, clean air. Underprovided by markets. Why it matters: Classic justification for government provision. Related: Common-pool resource, Free-rider problem, Externality

Random assignment / RCT

Domain: Micro (econometrics) Plain English: Subjects are randomly assigned to treatment or control, so observed differences in outcomes can be attributed causally to treatment. Gold standard for causal inference. Why it matters: Drove the credibility revolution in applied economics; 2019 Nobel to Banerjee-Duflo-Kremer for development RCTs. Related: Intention-to-treat (ITT), LATE (local average treatment effect), External validity

Regression discontinuity (RD)

Domain: Micro (econometrics) Plain English: Causal-inference design exploiting a sharp cutoff (an SAT score, an age threshold, a vote share) where treatment status changes discontinuously but other determinants of the outcome are continuous. Compares units just above and below the cutoff. Why it matters: One of the cleanest non-experimental designs; widely used in education, labor, and political economy. Related: Difference-in-differences (DiD), Instrumental variable (IV), Synthetic control

Repeated game

Domain: Micro (game theory) Plain English: A stage game played multiple times by the same players. Cooperation can be sustained via trigger strategies in infinite or indefinite horizons (see Folk theorem); finite repetition with known endpoint unravels. Why it matters: Models long-run business relationships, cartels, and international agreements. Related: Folk theorem, Subgame-perfect equilibrium, Reputation

Returns to scale

Domain: Micro Plain English: How output responds to a proportional increase in all inputs. Constant (output scales 1:1), increasing (output scales more than proportionately), decreasing (less). Cobb-Douglas with exponents summing to 1 has constant returns. Why it matters: Determines firm-size distribution and aggregation properties. Related: Economies of scale, Production function, Cobb-Douglas production function

Revelation principle

Domain: Micro (mechanism design) Plain English: Without loss of generality, any outcome achievable by some mechanism can be achieved by a direct-revelation mechanism in which players truthfully report their types. Lets designers restrict attention to truthful mechanisms. Why it matters: Powerful simplification that makes mechanism design tractable. Related: Mechanism design, Strategy-proof, VCG mechanism (Vickrey-Clarke-Groves)

Revenue equivalence theorem

Domain: Micro (auctions) Plain English: Under standard assumptions (independent private values, risk-neutral bidders, symmetric, no reserve, same allocation rule, same payoff to the lowest type), all auction formats yield the same expected revenue. Differences in practice come from violations of these assumptions. Why it matters: Disciplines naive claims that one auction format obviously raises more. Related: Auction (first-price sealed-bid), Auction (second-price sealed-bid / Vickrey), Private value (auction)

Roy model

Domain: Micro (labor) Plain English: Workers self-select into sectors (occupations, countries) based on comparative advantage. The observed wage distribution in each sector is a selected sample, biasing simple comparisons. Why it matters: Foundation for empirical work on migration, occupational choice, and selection bias. Related: Selection bias, Comparative advantage, Heckman selection

Screening

Domain: Micro Plain English: An uninformed party offers a menu of contracts designed so that better-informed parties self-select. Insurance with high-deductible/low-deductible options, or airline fare classes, are screening menus. Why it matters: Standard response to Adverse selection; analytically dual to Signaling (Spence). Related: Signaling (Spence), Adverse selection, Mechanism design

Signaling (Spence)

Domain: Micro Plain English: An informed party takes a costly action that is differentially costly across types in order to credibly signal their type. Spence's model: high-ability workers signal by getting education that's costly but less costly for them than for low-ability workers. Why it matters: Standard interpretation of part of the return to schooling; broadly applied to advertising, IPO underpricing, dividends. Related: Screening, Adverse selection, Human capital

Slutsky equation

Domain: Micro Symbol / formula: ∂x_i/∂p_j = ∂x_i^h/∂p_j − x_j·∂x_i/∂m Plain English: Decomposes the total effect of a price change on demand into the Substitution effect (compensated, holding utility constant) and the Income effect (change in real purchasing power). Why it matters: Foundational identity of demand theory; underlies welfare analysis and the math of compensating/equivalent variation. Related: Substitution effect, Income effect, Giffen good

Social cost of carbon (SCC)

Domain: Micro / Multi Plain English: The present-value dollar cost of one additional ton of CO₂ emissions, integrating future climate damages. EPA 2023 estimates around $190/ton (2.0% discount rate); earlier U.S. interagency working group used ~$51 (3% discount rate). Highly sensitive to discount rate and damage function. Why it matters: Reference price for carbon taxes, federal cost-benefit analyses, and corporate shadow pricing. Related: Carbon price, Pigouvian tax, Externality See also: covered in 03-microeconomics-sota.md §Environmental econ.

Status quo bias

Domain: Micro (behavioral) Plain English: Tendency to stick with whatever the current state is. Caused by Default effect, Loss aversion, and informational signals. Why it matters: Explains policy stickiness and the power of defaults in choice architecture. Related: Default effect, Loss aversion, Endowment effect

Structural estimation

Domain: Micro (econometrics) Plain English: Estimating the parameters of an explicit economic model (utility, production, behavioral) so the model fits observed data. Contrasts with reduced-form estimation, which estimates the relationship between outcomes and treatments without specifying the mechanism. Trade-off: more interpretable and counterfactual-capable, but more assumption-heavy. Why it matters: Necessary for policy counterfactuals like merger simulation or tax reform evaluation. Related: Reduced form, BLP (Berry-Levinsohn-Pakes), Discrete choice See also: covered in 03-microeconomics-sota.md §Structural vs reduced form.

Subgame-perfect equilibrium

Domain: Micro (game theory) Plain English: A Nash equilibrium that prescribes Nash play in every subgame, not just on the equilibrium path. Rules out non-credible threats. Found by backward induction in finite games. Why it matters: Standard refinement of Nash equilibrium for sequential games. Related: Nash equilibrium, Dynamic game, Backward induction

Substitution effect

Domain: Micro Plain English: The portion of demand response to a price change that comes from the change in relative prices, holding real income (utility) constant. Always pushes you away from the good that got more expensive. Why it matters: With Income effect, decomposes price effects via the Slutsky equation. Related: Income effect, Slutsky equation, Giffen good

Sufficient statistics approach

Domain: Micro (public) Plain English: Welfare analysis that expresses the welfare effect of a policy in terms of a small number of estimable "sufficient statistics" (elasticities) instead of estimating a full structural model. Chetty's framework. Why it matters: Bridges structural and reduced-form work; lets policy implications follow from credibly identified elasticities. Related: Structural estimation, Elasticity (price of demand), Optimal taxation (Mirrlees)

Sunk cost

Domain: Micro Plain English: A cost already incurred that cannot be recovered. Rationally, it should not affect forward-looking decisions; the Sunk cost fallacy is the human tendency to continue investing because of past commitments. Why it matters: Drives many bad project-continuation and consumer-loyalty decisions. Related: Opportunity cost, Sunk cost fallacy

Synthetic control

Domain: Micro (econometrics) Plain English: When one unit (a region, a country) receives a treatment, build a "synthetic" comparison from a weighted combination of untreated units that match the treated unit's pre-treatment trajectory. Compare post-treatment outcomes. Abadie-Diamond-Hainmueller. Why it matters: Powerful when only one or a few units are treated and pre-trends are long enough. Related: Difference-in-differences (DiD), Regression discontinuity (RD)

Taste-based discrimination

Domain: Micro (labor) Plain English: Becker's framework: employers, coworkers, or customers have a preference (taste) against a group and are willing to pay (in higher wages or lower profits) to avoid them. Should be eroded by competition but is empirically persistent. Why it matters: Distinguished from Discrimination (statistical) in policy and measurement. Related: Discrimination (statistical)

Top trading cycles (TTC)

Domain: Micro (market design) Plain English: Algorithm for object allocation (school seats, dorm rooms, kidney exchange) that is Pareto efficient and strategy-proof. Each agent points to their favorite object, each object points to its owner (or highest-priority claimant), trade along cycles. Why it matters: Used in many real-world allocation problems; complement and contrast to Deferred acceptance (Gale-Shapley). Related: Deferred acceptance (Gale-Shapley), Mechanism design, Strategy-proof

Treatment-on-the-treated (TOT / ATT)

Domain: Micro (econometrics) Plain English: Average treatment effect for those who actually received treatment, as opposed to those assigned (the Intention-to-treat (ITT) estimand). With perfect compliance the two coincide. Why it matters: Often the policy-relevant parameter (e.g., effect of a program on participants), but harder to identify without strong assumptions. Related: Intention-to-treat (ITT), LATE (local average treatment effect), Random assignment / RCT

Two-sided market

Domain: Micro / Multi Plain English: A market where a platform brings together two distinct user groups whose value to each other depends on the size of the other group (credit cards bring merchants and cardholders; ad-supported media bring viewers and advertisers). Optimal pricing often subsidizes one side. Why it matters: Foundation of Platform economics and modern antitrust analysis. Related: Platform economics, Network effects (direct vs indirect), Multi-homing

Utility

Domain: Micro Plain English: A numerical representation of preferences. Cardinal utility levels have no meaning — only orderings do. Special cases (expected utility, CRRA) impose more structure for risk and intertemporal choice. Why it matters: Object the consumer is assumed to maximize subject to a Budget constraint. Related: Marginal utility (MU), Preferences, Expected utility

VCG mechanism (Vickrey-Clarke-Groves)

Domain: Micro (mechanism design) Plain English: A direct-revelation mechanism for allocating goods that is efficient and strategy-proof: each agent pays an "externality price" equal to the harm their participation imposes on others. Generalizes the Auction (second-price sealed-bid / Vickrey). Why it matters: Theoretical benchmark for mechanism design; rarely used in pure form because of revenue and budget-balance issues. Related: Mechanism design, Strategy-proof, Revelation principle

Veblen good

Domain: Micro Plain English: A good for which demand rises with price because higher price signals exclusivity or status (luxury watches, some art). Not a violation of standard theory once status is in the utility function. Why it matters: Helps frame luxury pricing and conspicuous consumption. Related: Giffen good, Conspicuous consumption

Welfare theorems (first and second)

Domain: Micro Plain English: First: any competitive equilibrium (under standard assumptions) is Pareto efficient. Second: any Pareto-efficient allocation can be achieved as a competitive equilibrium given the right initial endowments and lump-sum transfers. The intellectual core of "markets work." Why it matters: Both theorems are widely invoked, often beyond their assumptions; the second is more aspirational than implementable because lump-sum transfers don't exist in practice. Related: Pareto efficient, General equilibrium

Winner's curse

Domain: Micro (auctions) Plain English: In a common-value auction with noisy private signals, winning is itself bad news — it means your signal was the most optimistic. Rational bidders shade their bids to compensate; naive bidders systematically overpay. Why it matters: Real-world hazard in oil and gas leases, M&A, and crypto NFT mints. Related: Common value (auction), Auction (first-price sealed-bid), Adverse selection

Macroeconomics terms

Ample reserves regime

Domain: Macro Plain English: A monetary operating framework in which the central bank supplies more reserves than banks demand, so the policy rate is set by administered rates (IORB, ONRRP) rather than by managing reserve scarcity. The Fed adopted this regime in 2019. Why it matters: Determines how QT and TGA flows transmit into money-market rates; replaced the pre-2008 "corridor" system. Related: IORB (Interest on Reserve Balances), ON RRP (Overnight Reverse Repo Facility), Scarce reserves, SRF (Standing Repo Facility) See also: covered in 02-macroeconomics-sota.md §Monetary operating framework.

Atlanta Fed wage tracker

Domain: Macro (labor) Plain English: Median wage growth among workers continuously employed for 12 months, computed from CPS micro data. Less distorted by composition shifts than aggregate average hourly earnings. Why it matters: Closely watched gauge of underlying wage pressure for the FOMC. Related: Employment Cost Index (ECI), Wage growth, Phillips curve

Automatic stabilizers

Domain: Macro (fiscal) Plain English: Features of the tax-and-transfer system that mechanically increase deficits in recessions and surpluses in booms — progressive income tax, unemployment insurance, food stamps. No new legislation required. Why it matters: Empirically the largest part of countercyclical fiscal policy in normal recessions. Related: Fiscal multiplier, Discretionary fiscal policy

Average inflation targeting (AIT / FAIT)

Domain: Macro Plain English: A monetary policy strategy in which the central bank aims for an average inflation rate (e.g., 2%) over time, deliberately tolerating overshoots after periods of undershooting. The Fed adopted "Flexible AIT" in August 2020 and dropped it in August 2025 in favor of standard flexible inflation targeting. Why it matters: Defining feature of the 2020–2025 Fed framework; intended to address persistently low inflation but was overtaken by the 2021–22 inflation surge. Related: Flexible inflation targeting, Forward guidance, Zero lower bound (ZLB) See also: covered in 02-macroeconomics-sota.md §Frameworks.

Balance of payments (BoP)

Domain: Macro (international) Plain English: Double-entry record of all transactions between a country and the rest of the world over a period. Split into current account (trade in goods and services + income flows), capital account, and financial account. Sums to zero by construction. Why it matters: Tracks external financing position and exchange-rate pressures. Related: Current account, Capital account / financial account, Savings-investment identity

Bank lending channel

Domain: Macro (transmission) Plain English: Monetary policy works partly by tightening or loosening banks' ability to lend, not just by changing the price of credit. Operates through deposit supply, capital constraints, and bank balance-sheet health. Why it matters: Important for understanding why monetary policy effects vary across cycles and across small vs large firms. Related: Credit channel, Balance sheet channel, Monetary transmission

Beige Book

Domain: Macro Plain English: Qualitative summary of economic conditions across the Fed's 12 districts, published eight times a year about two weeks before each FOMC meeting. Anecdotal rather than statistical. Why it matters: Signals real-time conditions ahead of hard data; sometimes useful for cross-checking BEA/BLS releases. Related: FOMC (Federal Open Market Committee), Dot plot (SEP)

Beveridge curve

Domain: Macro (labor) Plain English: Empirical negative relationship between the unemployment rate and the job vacancy rate. Outward shifts indicate worsening matching efficiency. The 2021–23 U.S. labor market showed an unusual outward shift, then partial reversal. Why it matters: Key gauge of labor-market tightness and a coordinate for Phillips curve analysis. Related: JOLTS (Job Openings and Labor Turnover Survey), NAIRU (Non-Accelerating Inflation Rate of Unemployment), Matching function

Breakeven inflation

Domain: Macro / Trading Symbol / formula: BEI = nominal yield − TIPS yield Plain English: The inflation rate at which holding a nominal Treasury and a TIPS of the same maturity would yield the same return. Combines an expected inflation component and an inflation risk premium. Why it matters: Real-time market-implied inflation expectations. Related: TIPS (Treasury Inflation-Protected Securities), Inflation swap, Term premium

Calvo pricing

Domain: Macro Plain English: Firms reset prices with constant probability per period (independent of how long they've held the current price). Workhorse assumption in NK models because it aggregates cleanly. Why it matters: Generates the New Keynesian Phillips curve (NKPC) in standard form. Related: Menu cost, Sticky prices, New Keynesian Phillips curve (NKPC)

Capital deepening

Domain: Macro Plain English: An increase in capital per worker. Raises output per worker in a standard production function but, with diminishing returns, eventually has shrinking effects. Why it matters: One of the three sources in Growth accounting alongside labor input and TFP. Related: Solow growth model, Total factor productivity (TFP)

Carbon price

Domain: Macro / Multi Plain English: A price per ton of CO₂ emissions, set either as a tax (Pigouvian) or via cap-and-trade permits. EU ETS auction prices fluctuated in the €60–90 range through 2024–25. Why it matters: Primary economic lever for climate mitigation; major channel of supply-side macro adjustment in transition scenarios. Related: Pigouvian tax, Social cost of carbon (SCC), NGFS scenarios

Climate physical risk

Domain: Macro / Multi Plain English: Macroeconomic and financial risk from the physical impacts of climate change — extreme weather, sea-level rise, chronic heat. Hits insurance, agriculture, real estate, and some sovereign balance sheets. Why it matters: Now a routine input in central-bank stress tests (NGFS scenarios). Related: Climate transition risk, NGFS scenarios

Climate transition risk

Domain: Macro / Multi Plain English: Macro and financial risk from the transition to a low-carbon economy — policy changes, technology shifts, stranded assets, demand reallocation. Often modeled as a carbon-price path. Why it matters: Central in supervisory stress tests and corporate transition planning. Related: Climate physical risk, NGFS scenarios, Carbon price

Core PCE

Domain: Macro Plain English: Personal Consumption Expenditures price index excluding food and energy. The Fed's preferred inflation gauge for the 2% target because of better coverage (substitution, healthcare) and lower volatility than CPI. Why it matters: Headline measure for the dual mandate. Related: CPI (Consumer Price Index), PCE (Personal Consumption Expenditures price index), Supercore inflation, Trimmed mean inflation

Cost-push inflation

Domain: Macro Plain English: Inflation driven by supply-side cost shocks (oil, supply chains, wages) rather than excess demand. 1970s OPEC shocks and 2021–22 supply-chain disruptions are textbook examples. Why it matters: Central banks face a sharper output-inflation trade-off in cost-push than in demand-pull episodes. Related: Demand-pull inflation, Supply shock, Wage-price spiral

CPI (Consumer Price Index)

Domain: Macro Plain English: BLS index of the prices of a fixed basket of consumer goods and services. Headline CPI includes everything; core excludes food and energy. Updated methodology blends Laspeyres-style fixed weights with annual chain-weighting. Why it matters: Most-cited U.S. inflation statistic; used in Social Security COLA and TIPS indexation. Related: Core PCE, PCE (Personal Consumption Expenditures price index), Supercore inflation, Trimmed mean inflation

Crowding out

Domain: Macro (fiscal) Plain English: Government borrowing raises interest rates and reduces private investment, partially offsetting the demand impulse of fiscal stimulus. Smaller or even reversed (crowding in) when monetary policy is at the Zero lower bound (ZLB) and the economy is demand-constrained. Why it matters: Core ingredient in any estimate of the Fiscal multiplier. Related: Fiscal multiplier, Ricardian equivalence

Current account

Domain: Macro (international) Plain English: Trade balance (goods + services) plus net income from abroad plus net current transfers. A deficit means a country imports more than it exports plus earns from abroad; financed by capital inflows. Why it matters: Core international position indicator; large persistent deficits/surpluses are often sources of macro vulnerability. Related: Balance of payments (BoP), Capital account / financial account, Savings-investment identity

Debt sustainability analysis (DSA)

Domain: Macro (fiscal) Plain English: IMF/EU framework for assessing whether a government's debt path is on a stable trajectory, given assumptions about growth, interest rates, primary balance, and contingent liabilities. Combines deterministic projections with stress tests. Why it matters: Trigger for IMF program design and EU fiscal surveillance; politically charged when judgments turn on contested parameters. Related: Debt-to-GDP ratio, Primary balance, R-G (r minus g)

Debt-to-GDP ratio

Domain: Macro (fiscal) Plain English: Gross or net government debt as a share of nominal GDP. Standard scale-free metric for fiscal position; the level is less important than the trajectory and the currency of denomination. Why it matters: Workhorse fiscal indicator; threshold concepts (e.g., the discredited Reinhart-Rogoff 90% cliff) should be treated with caution. Related: Primary balance, R-G (r minus g), Debt sustainability analysis (DSA)

Deanchoring (of inflation expectations)

Domain: Macro Plain English: When the public stops believing the central bank will return inflation to target, and instead extrapolates from recent inflation when forming expectations. Generates persistence and a worse output-inflation trade-off. Why it matters: Central concern during 2021–23 inflation surge; surveys (Michigan, NY Fed SCE) and breakevens were watched intently. Related: Anchored expectations, Breakeven inflation, Wage-price spiral

Deflator (GDP)

Domain: Macro Symbol / formula: GDP deflator = (nominal GDP / real GDP) · 100 Plain English: Implicit price index for everything produced in the domestic economy, derived from the ratio of nominal to real GDP. Differs from CPI in scope (includes investment goods, excludes imports). Why it matters: Broadest economy-wide price measure. Related: CPI (Consumer Price Index), PCE (Personal Consumption Expenditures price index), Real vs nominal

Demand-pull inflation

Domain: Macro Plain English: Inflation driven by excess aggregate demand relative to supply capacity. Classic case: heated labor market, output above potential, broad-based price rises. Why it matters: Conceptual contrast to Cost-push inflation; informs whether tighter monetary policy can do the job alone. Related: Cost-push inflation, Output gap, Phillips curve

Demographic dividend

Domain: Macro (long-run) Plain English: Growth boost from a temporary rise in the share of the population that is working-age. Was a major contributor to East Asia's 1960–2000 growth; many advanced economies now face the reverse (aging drag). Why it matters: Anchors very long-run growth projections. Related: Dependency ratio, Goodhart-Pradhan thesis

Dependency ratio

Domain: Macro (demographics) Plain English: Ratio of dependents (under 15 and over 64) to working-age population. Rising in most advanced economies and China, stable or falling in much of sub-Saharan Africa and South Asia. Why it matters: Drives long-run fiscal pressure on pensions and health care. Related: Demographic dividend, Goodhart-Pradhan thesis

Dixit-Stiglitz aggregator

Domain: Macro Plain English: CES aggregator over differentiated varieties producing a single composite good. Allows tractable monopolistic competition with constant markups in macro models. Why it matters: Standard market structure in NK models; ingredient of many trade and growth models. Related: Monopolistic competition, New Keynesian model, CES (Constant Elasticity of Substitution)

Dot plot (SEP)

Domain: Macro Plain English: Chart in the FOMC's Summary of Economic Projections showing each participant's anonymous projection of the appropriate federal funds rate at year-ends and in the longer run. Released quarterly. Why it matters: Closely watched as a guide to the FOMC's reaction function and forward guidance. Related: Dot plot (SEP), FOMC (Federal Open Market Committee), Forward guidance

DSGE (Dynamic Stochastic General Equilibrium) model

Domain: Macro Plain English: A class of macro models with microfounded behavior, intertemporal optimization, rational expectations, and shocks. Workhorses include the Smets-Wouters model and many central-bank in-house variants. Why it matters: Standard analytical engine for academic and policy macro since the 2000s; heavily criticized post-GFC for missing financial frictions, and increasingly augmented with HANK (Heterogeneous Agent New Keynesian) heterogeneity. Related: HANK (Heterogeneous Agent New Keynesian), TANK (Two-Agent New Keynesian), RANK (Representative Agent New Keynesian), RBC model (rbc-model / Real Business Cycle), New Keynesian model See also: covered in 02-macroeconomics-sota.md §Modeling.

Dual mandate

Domain: Macro Plain English: U.S. Federal Reserve's statutory objectives under the 1977 Federal Reserve Reform Act: maximum employment and stable prices. (A third "moderate long-term interest rates" is usually treated as derivative.) Why it matters: The legal foundation of Fed policy; contrasts with the ECB's primary price-stability mandate. Related: Average inflation targeting (AIT / FAIT), Flexible inflation targeting, FOMC (Federal Open Market Committee)

Effective Federal Funds Rate (EFFR)

Domain: Macro Plain English: Volume-weighted median rate on overnight unsecured loans between U.S. depository institutions, calculated by the NY Fed from FR 2420 data. The "policy rate" target is set as a range for EFFR. Why it matters: Operational target of U.S. monetary policy in the Ample reserves regime. Related: IORB (Interest on Reserve Balances), ON RRP (Overnight Reverse Repo Facility), SOFR (Secured Overnight Financing Rate)

Effective lower bound (ELB)

Domain: Macro Plain English: The lowest policy rate the central bank can or will set, recognizing that very negative rates can disrupt money markets and bank profitability. Some central banks (ECB, SNB, BoJ) went modestly negative; the Fed has not. Often used interchangeably with Zero lower bound (ZLB). Why it matters: Constrains conventional monetary policy near zero and motivates Forward guidance and QE (Quantitative Easing). Related: Zero lower bound (ZLB), QE (Quantitative Easing), Forward guidance

Employment Cost Index (ECI)

Domain: Macro (labor) Plain English: BLS quarterly index of total labor compensation (wages + benefits), holding the occupational mix fixed. Less subject to composition bias than average hourly earnings. Why it matters: One of the FOMC's preferred wage measures. Related: Atlanta Fed wage tracker, Phillips curve

Expectations channel

Domain: Macro (transmission) Plain English: Monetary policy works partly by shaping public expectations about future policy, inflation, and growth, which feed back into current decisions. Forward guidance is the explicit policy tool here. Why it matters: Becomes critical when conventional rate tools hit the ELB. Related: Forward guidance, Anchored expectations, Monetary transmission

Expectations-augmented Phillips curve

Domain: Macro Symbol / formula: π_t = π_t^e − a·(u_t − u*) + ε_t Plain English: Friedman-Phelps update of the original Phillips curve: inflation depends on expected inflation plus a term tied to the unemployment gap. Implies no long-run inflation-unemployment trade-off if expectations adjust. Why it matters: Resolved the 1970s "stagflation puzzle" and underlies all modern Phillips curve work. Related: Phillips curve, New Keynesian Phillips curve (NKPC), NAIRU (Non-Accelerating Inflation Rate of Unemployment)

FAIT (Flexible Average Inflation Targeting)

Domain: Macro Plain English: Specific 2020–2025 Fed framework: aim for 2% inflation on average over time, allow overshoots after persistent undershoots, and define "maximum employment" as a broad-based, inclusive goal with shortfalls (not deviations) of employment from estimates of its maximum level. Dropped in August 2025 framework review in favor of standard flexible inflation targeting. Why it matters: Shaped Fed reaction function during 2020–22; widely criticized for contributing to the slow start of the 2022 tightening. Related: Average inflation targeting (AIT / FAIT), Flexible inflation targeting, Dual mandate See also: covered in 02-macroeconomics-sota.md §Frameworks.

Fiscal multiplier

Domain: Macro (fiscal) Plain English: The dollar change in GDP per dollar of fiscal action (spending increase, tax cut). Empirically ranges from below 0.5 (small open economies, tax cuts to high-income households, normal times) to above 1.5 (transfers to low-income households, recessions, ZLB). Why it matters: Central object in evaluating any stimulus. Related: Crowding out, Automatic stabilizers, HANK (Heterogeneous Agent New Keynesian)

Fiscal theory of the price level (FTPL)

Domain: Macro Plain English: Theory in which the price level adjusts so that the real value of government debt equals the present value of expected future primary surpluses. Reverses the standard "monetary policy sets inflation" view. Why it matters: Cochrane and Leeper revived this around 2022–24 as one lens on the post-COVID inflation; remains debated. Related: MMT (Modern Monetary Theory), Debt sustainability analysis (DSA), Primary balance See also: covered in 02-macroeconomics-sota.md §Heterodox.

Flexible inflation targeting

Domain: Macro Plain English: A regime in which the central bank targets inflation over the medium run but accepts short-run deviations to stabilize output and employment. Most advanced-economy frameworks. Why it matters: Default benchmark against which Average inflation targeting (AIT / FAIT), Average inflation targeting (AIT / FAIT), and price-level targeting are compared. Related: Average inflation targeting (AIT / FAIT), Average inflation targeting (AIT / FAIT), Dual mandate

FOMC (Federal Open Market Committee)

Domain: Macro Plain English: The Fed's monetary policy committee — 12 voting members (7 Board governors plus 5 of 12 reserve bank presidents, rotating except the NY Fed which votes always). Meets 8 times a year. Why it matters: Sets U.S. policy rates and balance-sheet decisions; releases the Dot plot (SEP), Dot plot (SEP), and minutes. Related: Dot plot (SEP), Dot plot (SEP), Beige Book

Forward guidance

Domain: Macro Plain English: Central-bank communication about the likely future path of policy, intended to shape current expectations and asset prices. Delphic (forecast-like) vs Odyssean (commitment-like) varieties. Why it matters: Key unconventional tool at the Effective lower bound (ELB) and during transitions in framework. Related: Expectations channel, QE (Quantitative Easing), Zero lower bound (ZLB)

GDP (Gross Domestic Product)

Domain: Macro Plain English: Market value of all final goods and services produced within a country's borders in a period. Real GDP strips out inflation; nominal does not. Why it matters: Headline output measure; the denominator of most macro ratios. Related: GDI (Gross Domestic Income), GNP (Gross National Product), Real vs nominal, GDP deflator

GDP Nowcast (Atlanta Fed GDPNow)

Domain: Macro Plain English: Real-time model-based estimate of current-quarter real GDP growth, updated as monthly indicators are released. Maintained by the Atlanta Fed; the NY Fed Nowcast is a comparable BVAR-based alternative (paused as of late 2024). Why it matters: Closely watched for high-frequency reads on the cycle; commonly diverges from final BEA estimates. Related: Deflator (GDP), Beige Book

GDI (Gross Domestic Income)

Domain: Macro Plain English: Aggregate income generated in producing GDP — wages, profits, interest, rents. Conceptually equals GDP but in practice diverges due to measurement error ("statistical discrepancy"). Average of GDP and GDI sometimes used as a less noisy gauge. Why it matters: Useful cross-check on output; the divergence has been notable in 2023–24. Related: Deflator (GDP), GNP (Gross National Product)

GNP (Gross National Product)

Domain: Macro Plain English: Output produced by a country's residents, regardless of geography. GDP plus net factor income from abroad. Diverges from GDP for countries with large foreign investment positions (Ireland, Luxembourg). Why it matters: Mostly historical in the U.S. since the 1991 switch to GDP as headline; still central for some smaller economies. Related: Deflator (GDP), GNI (Gross National Income)

Golden rule of saving

Domain: Macro (growth) Plain English: In a Solow model, the saving rate that maximizes steady-state consumption per worker. Sets marginal product of capital equal to the rate of population growth plus depreciation. Why it matters: Welfare benchmark in growth theory. Related: Solow growth model, Capital deepening

Goodhart-Pradhan thesis

Domain: Macro (long-run) Plain English: The argument (in The Great Demographic Reversal, 2020) that aging populations and the reversal of China's labor supply shock will produce structurally higher inflation, higher real rates, and a renewed labor bargaining power. Controversial. Why it matters: Counterpoint to the Secular stagnation thesis; central in debates about the path of r-star (r*). Related: Secular stagnation, r-star (r*), Demographic dividend

Growth accounting

Domain: Macro (growth) Symbol / formula: ΔY/Y = α·ΔK/K + (1−α)·ΔL/L + ΔA/A Plain English: Decomposition of output growth into contributions from capital, labor, and total factor productivity. TFP is the "Solow residual" — what's left over after accounting for measured inputs. Why it matters: Standard framework for cross-country growth comparisons. Related: Solow residual, Total factor productivity (TFP), Solow growth model

HANK (Heterogeneous Agent New Keynesian)

Domain: Macro Plain English: A class of New Keynesian models with heterogeneous households, incomplete markets, and idiosyncratic income risk. Many households are constrained or near-constrained (Hand-to-mouth household), so the marginal propensity to consume varies sharply across the income distribution and aggregate consumption responses are bigger than RANK predicts. Why it matters: Recasts monetary and fiscal transmission, the fiscal multiplier, and the role of redistribution; central to research since Kaplan-Moll-Violante 2018. Related: RANK (Representative Agent New Keynesian), TANK (Two-Agent New Keynesian), Hand-to-mouth household, Wealthy hand-to-mouth (WHtM), iMPC (intertemporal MPC) See also: covered in 02-macroeconomics-sota.md §HANK and 04-micro-macro-intermingling.md §HANK lineage.

Hand-to-mouth household

Domain: Macro Plain English: A household whose consumption tracks current income closely because of binding borrowing constraints or behavioral frictions. Includes both poor households (with no liquid assets) and "wealthy hand-to-mouth" (with illiquid wealth but little liquid). Why it matters: Key behavioral primitive in HANK (Heterogeneous Agent New Keynesian); explains large empirical MPCs out of transitory income. Related: Wealthy hand-to-mouth (WHtM), MPC (Marginal Propensity to Consume), HANK (Heterogeneous Agent New Keynesian)

Hawk / Dove

Domain: Macro (slang) Plain English: Hawks emphasize inflation risk and favor tighter policy; doves emphasize employment risk and favor easier policy. Loose labels rather than formal positions. Why it matters: Standard shorthand for FOMC member preferences and rhetoric. Related: FOMC (Federal Open Market Committee), Dot plot (SEP)

Hysteresis

Domain: Macro Plain English: Lasting effects of temporary shocks. A deep recession can permanently raise unemployment (workers lose skills, drop out of the labor force) or lower potential output (canceled investment, lost capacity). Reverse hysteresis is sometimes proposed for hot labor markets. Why it matters: Tilts the cost-benefit calculation toward forceful stabilization policy. Related: Secular stagnation, Scarring, Output gap

Impulse response function (IRF)

Domain: Macro (econometrics) Plain English: Time path of an endogenous variable in response to a one-time shock to another variable, holding all else constant. Standard summary statistic of VAR and DSGE models. Why it matters: How most macro shock-and-propagation results are communicated. Related: VAR-econometrics (Vector Autoregression), DSGE (Dynamic Stochastic General Equilibrium) model, Narrative identification

iMPC (intertemporal MPC)

Domain: Macro Plain English: The path of consumption responses to an income shock — not just the first-quarter MPC, but the full sequence over subsequent quarters. Auclert-Rognlie-Straub showed empirical iMPCs are flatter than DSGE/RANK models predict, partly explaining HANK's relevance. Why it matters: Disciplines the dynamic predictions of HANK and TANK models against micro evidence. Related: MPC (Marginal Propensity to Consume), HANK (Heterogeneous Agent New Keynesian), Hand-to-mouth household

IORB (Interest on Reserve Balances)

Domain: Macro Plain English: Rate the Fed pays on reserves held by banks at the Fed. Sets a floor on the federal funds rate (banks shouldn't lend below what they can earn risk-free). Replaced IOER in 2021. Why it matters: Primary administered rate in the Ample reserves regime. Related: ON RRP (Overnight Reverse Repo Facility), Ample reserves regime, SRF (Standing Repo Facility)

IS-LM model

Domain: Macro Plain English: Hicks's textbook depiction of short-run equilibrium: the IS curve plots output-interest-rate combinations consistent with goods-market equilibrium; the LM curve plots those consistent with money-market equilibrium. Largely supplanted in research by DSGE (Dynamic Stochastic General Equilibrium) model and three-equation NK frameworks but still useful pedagogically. Why it matters: Common reference for intuition even though the LM is awkward when central banks set interest rates directly. Related: AS-AD model, Mundell-Fleming, New Keynesian model

JOLTS (Job Openings and Labor Turnover Survey)

Domain: Macro (labor) Plain English: BLS monthly survey of job openings, hires, quits, and separations. The quits rate is closely watched as a worker-confidence indicator (people quit when they're sure they can find better jobs). Why it matters: Core input to Beveridge curve analysis and assessments of labor-market tightness. Related: Beveridge curve, Quits rate

K-shaped recovery

Domain: Macro Plain English: A recovery in which some sectors and demographic groups rebound strongly while others continue to lag, producing a K-shaped divergence in fortunes. Frequently invoked for the post-COVID period. Why it matters: Common framing for inequality during the cycle; sometimes more rhetoric than measurement. Related: Scarring, Hysteresis, HANK (Heterogeneous Agent New Keynesian)

Labor force participation (LFPR)

Domain: Macro (labor) Plain English: Share of the working-age population either employed or actively looking for work. U.S. prime-age (25–54) LFPR is the cleanest gauge because it's less affected by aging and schooling decisions. Why it matters: Together with unemployment defines slack; affects measurement of NAIRU. Related: U-3, U-6, NAIRU (Non-Accelerating Inflation Rate of Unemployment)

Labor productivity

Domain: Macro Symbol / formula: Y/L (output per hour or per worker) Plain English: Output per unit of labor input. Drives long-run wages; combines capital deepening, technology, and labor quality. Why it matters: One of the deepest determinants of living standards. Related: Total factor productivity (TFP), Capital deepening, Growth accounting

Markup

Domain: Macro / Micro Symbol / formula: μ = P / MC Plain English: Ratio of price to marginal cost. In macro, the aggregate markup proxies for the degree of pricing power in the economy; rising aggregate markups (De Loecker-Eeckhout-Unger) are central in recent debates about competition and labor share. Why it matters: Links micro market power to macro outcomes (inflation, labor share, investment). Related: Monopolistic competition, Kalecki markup, Market power See also: covered in 04-micro-macro-intermingling.md §Aggregate markups.

MMT (Modern Monetary Theory)

Domain: Macro Plain English: Heterodox framework arguing that a government issuing its own currency is not budget-constrained in nominal terms; the real constraint on spending is inflation. Largely rejected by mainstream academic macro but influential in some policy circles. Why it matters: Sharpens debate about fiscal limits; treated by most empirical analysts as a partial-truth observation about monetary sovereignty rather than a complete policy framework. Related: Fiscal theory of the price level (FTPL), Debt-to-GDP ratio, Ricardian equivalence

Monetary transmission

Domain: Macro Plain English: The set of channels through which monetary policy affects real activity and prices — interest rate, exchange rate, asset price, bank lending, credit, balance sheet, expectations, risk-taking. Effects come with long and variable lags. Why it matters: Determines how quickly and through what mix of channels tightening or easing reaches the economy. Related: Bank lending channel, Credit channel, Balance sheet channel, Expectations channel

MPC (Marginal Propensity to Consume)

Domain: Macro Plain English: Fraction of an additional dollar of income spent on consumption. Empirically varies sharply by liquid wealth and income — low-income, hand-to-mouth households often have MPCs of 0.3–0.7 in the year of receipt; wealthy households can be near zero. Why it matters: Central parameter in fiscal-multiplier calculation; the heterogeneity is the engine of HANK. Related: MPS (Marginal Propensity to Save), iMPC (intertemporal MPC), Hand-to-mouth household, HANK (Heterogeneous Agent New Keynesian)

MPS (Marginal Propensity to Save)

Domain: Macro Plain English: Fraction of an additional dollar of income saved (1 − MPC). For a balanced-budget household, MPC + MPS = 1. Why it matters: Mirror image of MPC; appears in classic Keynesian-multiplier arithmetic. Related: MPC (Marginal Propensity to Consume), Savings-investment identity

Mundell-Fleming

Domain: Macro (international) Plain English: Open-economy extension of IS-LM. Implies that monetary policy is potent under floating exchange rates and impotent under fixed rates; fiscal policy is the reverse. Underpins the Trilemma (international finance). Why it matters: Conceptual frame for thinking about open-economy policy mixes. Related: Trilemma (international finance), IS-LM model, Exchange rate regime

NAIRU (Non-Accelerating Inflation Rate of Unemployment)

Domain: Macro (labor) Plain English: The unemployment rate consistent with stable inflation. Time-varying, unobserved, and estimated with wide uncertainty. Conceptual cousin of the "natural rate of unemployment." Why it matters: Key input to Phillips curve and output-gap estimates, but its haze means it shouldn't drive policy mechanically. Related: Phillips curve, Output gap, U-3

NEER and REER (neer-reer / Nominal and Real Effective Exchange Rate)

Domain: Macro (international) Plain English: Trade-weighted index of a currency's value against a basket of partners. Real version deflates by relative prices to capture purchasing power. BIS and IMF publish standard series. Why it matters: Tracks competitiveness and aggregate exchange-rate movements better than any single bilateral rate. Related: Real exchange rate, PPP (Purchasing Power Parity), Trade-weighted dollar

New Keynesian model

Domain: Macro Plain English: Modern workhorse DSGE class with monopolistic competition, sticky prices (typically Calvo), and rational expectations. Three-equation textbook version: NK Phillips curve, dynamic IS, Taylor rule. Why it matters: Default analytical engine in central banks and academic macro; baseline against which HANK, finance frictions, and behavioral extensions are compared. Related: New Keynesian Phillips curve (NKPC), DSGE (Dynamic Stochastic General Equilibrium) model, HANK (Heterogeneous Agent New Keynesian), Taylor rule

New Keynesian Phillips curve (NKPC)

Domain: Macro Symbol / formula: π_t = β·E_t[π_{t+1}] + κ·x_t (+ cost-push shock) Plain English: Inflation depends on expected future inflation and current output gap (or marginal cost). Derived from Calvo pricing in a NK model. Empirically fits better in "hybrid" form with a lagged inflation term. Why it matters: Central pricing equation in modern macro; debates around its slope ("flat Phillips curve") drive much policy discussion. Related: Phillips curve, Calvo pricing, New Keynesian model

NGFS scenarios

Domain: Macro / Multi Plain English: Climate scenarios published by the Network for Greening the Financial System (a coalition of central banks and supervisors), used for stress testing financial firms against orderly, disorderly, and hot-house-world climate paths. Why it matters: De facto standard reference set for climate-stress macro analysis. Related: Climate physical risk, Climate transition risk, Carbon price

NNP (Net National Product)

Domain: Macro Plain English: GNP minus depreciation of the capital stock. Closer in spirit to "income available for consumption without eating into capital." Rarely the headline number but conceptually correct. Why it matters: Foundation for sustainability and green-accounting adjustments. Related: GNP (Gross National Product), Deflator (GDP), Capital consumption allowance

Okun's Law

Domain: Macro Symbol / formula: ΔY/Y* ≈ −c·(Δu), with c ≈ 2 in the U.S. Plain English: Empirical relationship between output gap and unemployment gap — a 1 percentage point rise in unemployment is associated with roughly a 2% loss of output. Coefficient varies across countries and over time. Why it matters: Pragmatic shortcut between labor-market and output measures of slack. Related: Output gap, NAIRU (Non-Accelerating Inflation Rate of Unemployment)

ON RRP (Overnight Reverse Repo Facility)

Domain: Macro Plain English: Fed facility that allows eligible counterparties (mostly MMFs and GSEs) to lend cash overnight to the Fed against Treasury collateral at an administered rate. Sets a soft floor on overnight money-market rates. Why it matters: ON RRP balances ballooned to ~$2.5T in 2022 and have since drained; their level signals the system's reserve abundance. Related: IORB (Interest on Reserve Balances), Ample reserves regime, SRF (Standing Repo Facility), Money market fund (MMF)

Output gap

Domain: Macro Symbol / formula: (Y − Y*) / Y* Plain English: Difference between actual and potential output, expressed as a share of potential. Positive = economy running hot, negative = slack. Why it matters: Determinant of inflation in Phillips curve and Taylor rule formulations; notoriously hard to measure in real time. Related: Potential output, NAIRU (Non-Accelerating Inflation Rate of Unemployment), Phillips curve

PCE (Personal Consumption Expenditures price index)

Domain: Macro Plain English: BEA price index covering consumer purchases, with chain-weighting and broader scope than CPI (includes spending on behalf of households, e.g., employer-paid health insurance). Core PCE is the Fed's preferred target. Why it matters: Headline U.S. inflation measure for the Fed. Related: Core PCE, CPI (Consumer Price Index), Supercore inflation

Phillips curve

Domain: Macro Plain English: Empirical inverse relationship between unemployment and inflation (Phillips 1958). Subsequently augmented by expectations (Friedman-Phelps) and forward-looking expectations (NKPC). Has appeared "flat" in recent decades, debated whether that's anchoring of expectations, measurement, or structural change. Why it matters: Central pricing equation in macro since the late 1950s. Related: Expectations-augmented Phillips curve, New Keynesian Phillips curve (NKPC), NAIRU (Non-Accelerating Inflation Rate of Unemployment)

Potential output

Domain: Macro Plain English: Sustainable level of output the economy can produce given technology, labor, and capital without generating accelerating inflation. CBO publishes a widely-cited U.S. series; in real time it's hard to pin down. Why it matters: Anchor for measuring slack and the Output gap. Related: Output gap, Total factor productivity (TFP), NAIRU (Non-Accelerating Inflation Rate of Unemployment)

PPI (Producer Price Index)

Domain: Macro Plain English: BLS index of selling prices received by domestic producers. Tracks inflation upstream of consumer prices; correlates with later CPI movements with a lag. Why it matters: Early indicator of cost pressures; sometimes used in supply-chain analysis. Related: CPI (Consumer Price Index), PCE (Personal Consumption Expenditures price index), GDP deflator

PPP (Purchasing Power Parity)

Domain: Macro (international) Plain English: Theory that exchange rates adjust to equalize the price of a basket of goods across countries. In practice holds only loosely and over long horizons. PPP-adjusted GDP comparisons are used to compare living standards across countries with very different price levels. Why it matters: Indispensable for cross-country comparisons; deviations from PPP are themselves a forecast variable. Related: NEER and REER (neer-reer / Nominal and Real Effective Exchange Rate), Real exchange rate

Primary balance

Domain: Macro (fiscal) Plain English: Government budget balance excluding interest payments on debt. The right metric for Debt sustainability analysis (DSA) because it isolates the policy-controlled fiscal stance from legacy interest costs. Why it matters: Determines whether debt-to-GDP rises or falls given growth and interest rates. Related: Debt sustainability analysis (DSA), Debt-to-GDP ratio, R-G (r minus g)

Productivity (TFP)

Domain: Macro Plain English: See Total factor productivity (TFP). Output per unit of all inputs combined; the residual after accounting for measured capital and labor. Related: Total factor productivity (TFP), Labor productivity

QE (Quantitative Easing)

Domain: Macro Plain English: Large-scale central-bank purchases of long-dated securities (Treasuries, MBS, in some cases corporate or sovereign) financed by reserve creation. Aimed at compressing term premia, supporting asset prices, and easing financial conditions when the policy rate is at the Effective lower bound (ELB). Why it matters: Defining unconventional tool of 2008–2022 era. Effects on real activity remain contested. Related: QT (Quantitative Tightening), Term premium, Forward guidance, Zero lower bound (ZLB)

QT (Quantitative Tightening)

Domain: Macro Plain English: Reduction in the central bank's balance sheet, either passively (letting securities run off as they mature) or actively (selling them). Reverses QE. Why it matters: Tightens financial conditions and drains reserves; balance-sheet runoff caps are part of forward guidance. Related: QE (Quantitative Easing), Ample reserves regime, ON RRP (Overnight Reverse Repo Facility)

R-G (r minus g)

Domain: Macro (fiscal) Symbol / formula: r − g, where r is the real interest rate on government debt and g is real GDP growth Plain English: When r < g, primary deficits can persist indefinitely without exploding debt-to-GDP — debt grows slower than the economy. When r > g, deficits raise debt-to-GDP, and you need primary surpluses to stabilize. Blanchard (2019) revived this framing. Why it matters: Central to post-2019 debates about fiscal capacity; r − g flipped positive in many advanced economies in 2022–24. Related: Debt sustainability analysis (DSA), Debt-to-GDP ratio, Secular stagnation

r-star (r*)

Domain: Macro Plain English: The neutral or natural real interest rate — the short-term real rate consistent with the economy operating at potential and inflation at target in the medium run. Unobserved; estimated (Holston-Laubach-Williams, Lubik-Matthes) with very wide bands. Why it matters: Reference rate for whether policy is loose or tight; debates about r* drive long-end yields and policy frameworks. Related: Natural rate of interest, Secular stagnation, Goodhart-Pradhan thesis

RANK (Representative Agent New Keynesian)

Domain: Macro Plain English: The classical NK model with a single representative household. Smooth consumption responses, low MPC, monetary transmission driven primarily by intertemporal substitution. Why it matters: Textbook benchmark; HANK and TANK are responses to its empirical limitations. Related: HANK (Heterogeneous Agent New Keynesian), TANK (Two-Agent New Keynesian), New Keynesian model

Rational inattention

Domain: Macro Plain English: Agents allocate limited attention optimally across decisions, generating sticky and noisy responses to information. Sims's approach; an alternative microfoundation for price and information stickiness. Why it matters: Provides a microfounded alternative to Calvo pricing and sticky information; relevant for understanding pass-through. Related: Sticky information, Sticky prices, Calvo pricing

RBC model (rbc-model / Real Business Cycle)

Domain: Macro Plain English: Kydland-Prescott class of DSGE models in which business cycles are optimal responses to real (technology) shocks, with no role for monetary policy. Foundational methodology even though most economists no longer think the substantive view fits the data. Why it matters: Methodological forerunner of modern DSGE; sharpened the discipline of microfounded macro. Related: DSGE (Dynamic Stochastic General Equilibrium) model, New Keynesian model, Solow residual

Real exchange rate

Domain: Macro Symbol / formula: q = e · P*/P Plain English: Nominal exchange rate adjusted for relative price levels. Tracks competitiveness and consumption-basket comparability across countries. Why it matters: Anchor for trade balance and capital flow analysis. Related: NEER and REER (neer-reer / Nominal and Real Effective Exchange Rate), PPP (Purchasing Power Parity)

Real vs nominal

Domain: Macro Plain English: Nominal is in current-dollar terms; real strips out inflation and is in constant-dollar terms (relative to a chosen base year). Real GDP, real wages, real interest rates are the inflation-adjusted versions. Why it matters: Confusing the two distorts comparisons across time and policy analysis. Related: Deflator (GDP), Deflator (GDP), Real interest rate

Recession dating (NBER BCDC)

Domain: Macro Plain English: U.S. recessions are dated by the NBER Business Cycle Dating Committee, which identifies peaks and troughs in aggregate economic activity based on a broad set of indicators (output, employment, real income, sales). Often announced months after the fact. Why it matters: Official U.S. recession chronology; differs from popular "two negative GDP quarters" definition. Related: Sahm rule, Deflator (GDP)

REER

Domain: Macro (international) Plain English: See NEER and REER (neer-reer / Nominal and Real Effective Exchange Rate). Related: NEER and REER (neer-reer / Nominal and Real Effective Exchange Rate), Real exchange rate

Ricardian equivalence

Domain: Macro (fiscal) Plain English: Barro's proposition: under specific conditions (infinitely lived households, lump-sum taxes, perfect capital markets), the timing of taxes does not matter — households see debt-financed tax cuts as future taxes and save the difference. Empirically, the conditions fail and Ricardian equivalence is only partial. Why it matters: Theoretical benchmark for why the financing mix of fiscal policy might (or might not) matter. Related: Crowding out, Fiscal multiplier, MMT (Modern Monetary Theory)

Sahm rule

Domain: Macro Plain English: Claudia Sahm's empirical rule: the U.S. economy is in recession when the 3-month moving average of the unemployment rate has risen 0.5 pp or more above its 12-month low. Triggered in mid-2024, then partially un-triggered as employment growth resumed — a reminder it's an indicator, not a definition. Why it matters: Real-time recession signal, widely cited in 2024–25. Related: Recession dating (NBER BCDC), U-3

Scarring

Domain: Macro Plain English: Persistent damage to workers and firms from a recession — lost skills, missed cohort earnings trajectories, foregone investment, dissolved relationships — that depresses output for years. Subset of Hysteresis. Why it matters: Strengthens the case for forceful stabilization. Related: Hysteresis, K-shaped recovery

SEP (Summary of Economic Projections)

Domain: Macro Plain English: Quarterly FOMC release with each participant's projections for GDP growth, unemployment, PCE inflation, and the appropriate federal funds rate over the next several years and the longer run. Includes the Dot plot (SEP). Why it matters: Most-watched window into FOMC participants' reaction functions. Related: Dot plot (SEP), FOMC (Federal Open Market Committee), Longer-run projections

Secular stagnation

Domain: Macro Plain English: Larry Summers's 2013 framing (with intellectual roots in Alvin Hansen): a chronic shortfall of demand relative to potential output, manifest in low real rates, low investment, and low inflation. Debated whether the 2022–25 cycle invalidated the thesis or merely paused it. Why it matters: Major interpretive frame for the 2008–2021 era; intertwined with debates over r-star (r*). Related: r-star (r*), Zero lower bound (ZLB), Goodhart-Pradhan thesis

Solow growth model

Domain: Macro (growth) Plain English: Workhorse neoclassical growth model: output produced from capital and labor with diminishing returns, capital accumulated from saving net of depreciation. Predicts convergence to a steady state where growth comes only from exogenous technological progress. Why it matters: Foundation for thinking about long-run growth; clarified the centrality of TFP and capital deepening. Related: Capital deepening, Total factor productivity (TFP), Growth accounting

Solow residual

Domain: Macro (growth) Plain English: The portion of output growth not explained by measured growth in capital and labor inputs. Attributed to technology / total factor productivity; conceptually a "measure of our ignorance." Why it matters: Empirical proxy for TFP and a constant reminder of measurement limits. Related: Total factor productivity (TFP), Growth accounting

SRF (Standing Repo Facility)

Domain: Macro Plain English: Fed facility, made permanent in July 2021, that offers overnight repo against Treasury/agency/MBS collateral at an administered rate. Provides a ceiling for repo rates and limits the risk of repo-market spikes like September 2019. Why it matters: Backstop ensuring smooth functioning of money markets in the Ample reserves regime. Related: Ample reserves regime, IORB (Interest on Reserve Balances), ON RRP (Overnight Reverse Repo Facility)

Sticky-price CPI

Domain: Macro Plain English: Subset of CPI components (constructed by the Atlanta Fed) whose prices change infrequently; tends to embody longer-horizon inflation expectations. Counterpart is "flexible-price CPI" (food, energy, gasoline). Why it matters: Used as a signal of underlying inflation dynamics. Related: Supercore inflation, Trimmed mean inflation, Core PCE

Supercore inflation

Domain: Macro Plain English: Informal label for core services excluding shelter; popularized by Jerome Powell in late 2022 as the slow-moving component most tied to wage growth. Increasingly tracked alongside core PCE. Why it matters: Watched as a gauge of services inflation persistence. Related: Core PCE, Trimmed mean inflation, Wage growth

Supply shock

Domain: Macro Plain English: A shift in aggregate supply — oil price, productivity, supply chains, weather — that moves output and inflation in opposite directions in the short run. Contrast with Demand shock. Why it matters: Creates the worst trade-offs for monetary policy. Related: Cost-push inflation, Oil shock, Stagflation

TANK (Two-Agent New Keynesian)

Domain: Macro Plain English: Simplified version of HANK with two types of households — savers and hand-to-mouth — and otherwise standard NK ingredients. Captures the qualitative consumption-MPC channel without full distributional dynamics. Why it matters: Tractable laboratory for studying how household heterogeneity affects monetary and fiscal policy. Related: HANK (Heterogeneous Agent New Keynesian), RANK (Representative Agent New Keynesian), Hand-to-mouth household

Taylor rule

Domain: Macro Symbol / formula: i_t = r* + π_t + φ_π·(π_t − π*) + φ_y·(y_t − y*) Plain English: Simple feedback rule that prescribes the policy rate as the neutral rate plus the inflation gap times a coefficient (>1, per Taylor principle) plus the output gap times another coefficient. The 1993 Taylor rule used φ_π=φ_y=0.5. Why it matters: Benchmark for evaluating monetary policy stance; FOMC frequently compared against various Taylor specifications. Related: Taylor principle, r-star (r*), New Keynesian model

Taylor principle

Domain: Macro Plain English: For a determinate, stable inflation equilibrium, the nominal policy rate should rise more than one-for-one with inflation. Violations can generate self-fulfilling inflation or deflation. Why it matters: Necessary condition for monetary anchoring in standard NK models. Related: Taylor rule, New Keynesian model

Term premium

Domain: Macro / Trading Plain English: Extra yield that investors demand for holding a long-dated bond instead of rolling short bonds. Inferred (not directly observed) from models like ACM (Adrian-Crump-Moench) or Kim-Wright. Sensitive to inflation risk, supply, and convenience yield. Why it matters: Decomposes long yields into expectations and risk; explains "puzzles" like the 2014 yield drop and 2023 long-rate spike. Related: Expectations hypothesis (term structure), Yield curve, Breakeven inflation See also: covered in 02-macroeconomics-sota.md §Term structure.

TIPS (Treasury Inflation-Protected Securities)

Domain: Macro / Trading Plain English: U.S. Treasuries whose principal is indexed to CPI. Their yield is a real yield; the gap with a nominal Treasury of the same maturity is the Breakeven inflation rate. Why it matters: Primary on-market source of real-rate and inflation-expectation information. Related: Breakeven inflation, Inflation swap, Real interest rate

Total factor productivity (TFP)

Domain: Macro Plain English: Component of output growth not attributable to growth in labor and capital. A composite of technology, organizational improvements, intangible capital, and measurement error. Long-run growth is overwhelmingly TFP-driven. Why it matters: Single most important driver of cross-country differences in income. Related: Solow residual, Growth accounting, Labor productivity

Trilemma (international finance)

Domain: Macro (international) Plain English: A country can have at most two of: free capital mobility, fixed exchange rate, independent monetary policy. The Mundell-Fleming trilemma. Rey's "dilemma" sharpens this to a binary: with open capital, monetary independence requires capital controls regardless of regime. Why it matters: Frames the policy choices of emerging market policymakers and post-Bretton Woods regimes. Related: Mundell-Fleming, Capital controls, Exchange rate regime

Trimmed mean inflation

Domain: Macro Plain English: Inflation rate calculated by excluding the most extreme price changes (top and bottom percentiles) each period. Dallas Fed Trimmed Mean PCE and Cleveland Fed Median CPI are leading examples. Less noisy than headline or core. Why it matters: Robust gauges of underlying inflation, especially when relative prices are moving sharply. Related: Core PCE, Sticky-price CPI

U-3

Domain: Macro (labor) Plain English: BLS official unemployment rate: unemployed (actively looking, available for work) as a share of the labor force. The headline number reported each month. Why it matters: Most cited single labor-market statistic. Related: U-6, Labor force participation (LFPR), NAIRU (Non-Accelerating Inflation Rate of Unemployment)

U-6

Domain: Macro (labor) Plain English: Broader BLS unemployment measure: U-3 plus marginally attached workers (have stopped looking but want to work) plus those working part-time for economic reasons. Always higher than U-3. Why it matters: Captures slack invisible in U-3, especially during recoveries. Related: U-3, Labor force participation (LFPR)

Wage-price spiral

Domain: Macro Plain English: A self-reinforcing pattern in which higher wages raise costs, which raise prices, which raise wage demands, and so on. Largely absent in the 2021–24 inflation episode according to IMF and ECB research, though tightly debated in real time. Why it matters: Central bank fear case during inflation episodes; existence depends on expectations anchoring and bargaining power. Related: Second-round effects, Anchored expectations, Phillips curve

Wealthy hand-to-mouth (WHtM)

Domain: Macro Plain English: Households with substantial illiquid wealth (housing equity, retirement accounts) but little liquid wealth. Behave more like poor households than like wealthy ones in response to income shocks. Kaplan-Violante coined the term. Why it matters: Explains why measured MPCs are high even in middle-income households; central piece of HANK's empirical case. Related: Hand-to-mouth household, MPC (Marginal Propensity to Consume), HANK (Heterogeneous Agent New Keynesian)

Yield curve control (YCC)

Domain: Macro Plain English: Central-bank policy of pegging a target yield at a specific maturity (often the 10-year). Bank of Japan pursued YCC at the 10-year from 2016, scrapped it in March 2024; Reserve Bank of Australia tried it briefly during COVID. Why it matters: Strong commitment device that delegates balance-sheet expansion to whatever volume is needed to defend the yield. Related: QE (Quantitative Easing), Forward guidance, Term premium

Zero lower bound (ZLB)

Domain: Macro Plain English: The constraint that nominal interest rates cannot fall meaningfully below zero (because households can hold currency). In practice the binding floor is below zero (Effective lower bound (ELB)) because of frictions. Why it matters: Forces use of unconventional tools — QE (Quantitative Easing), Forward guidance, YCC, fiscal policy. Related: Effective lower bound (ELB), QE (Quantitative Easing), Forward guidance

Market trading terms

0DTE (zero-days-to-expiry) options

Domain: Trading Plain English: Options expiring the same trading day. CBOE expanded SPX options to daily expirations in 2022, and 0DTE flow exploded to ~40–50% of SPX option volume by 2023–24. Heavily traded by retail and systematic flows. Why it matters: Dramatically increased intraday gamma and dealer-hedging flows; debated as a potential amplifier of intraday moves. Related: 1DTE / weeklies / LEAPS, 1DTE / weeklies / LEAPS, Gamma squeeze, Greeks (options Greeks)

1DTE / weeklies / LEAPS

Domain: Trading Plain English: 1DTE = expires next trading day; weeklies = expire each Friday; LEAPS = Long-Term Equity Anticipation Securities, expirations over a year out (up to ~3 years). Different liquidity and Greeks profiles. Related: 0DTE (zero-days-to-expiry) options, Greeks (options Greeks), Options (calls and puts)

Active share

Domain: Trading Symbol / formula: Σ |w_i^portfolio − w_i^benchmark| / 2 Plain English: Share of a portfolio's holdings that differ from its benchmark. Funds with active share below ~60% are sometimes labeled "closet indexers." Cremers-Petajisto. Why it matters: Diagnostic for whether active fees are buying active management. Related: Tracking error, Information ratio (IR), Smart beta

Adverse selection (market making)

Domain: Trading Plain English: Market makers lose when they trade with better-informed counterparties; quoted spreads widen to compensate. Decomposes the bid-ask spread into adverse-selection, order-processing, and inventory components. Why it matters: Foundational microstructure concept linking informed trading to liquidity costs. Related: Glosten-Milgrom model, Kyle model, Bid-ask spread

Almgren-Chriss model

Domain: Trading Plain English: Standard execution-cost model that trades off market impact (worse with faster execution) against price-risk variance (worse with slower execution). Yields a schedule (execution trajectory) that minimizes a mean-variance cost criterion. Why it matters: Foundational framework for VWAP/TWAP/IS algos and quantitative execution. Related: Implementation shortfall (IS), Market impact, IS algorithm (Implementation Shortfall)

Alpha

Domain: Trading Plain English: Return that cannot be explained by exposure to known systematic risk factors (in CAPM, the intercept after controlling for beta). Practitioner shorthand for any excess return attributed to skill rather than risk. Three subtly different uses: (1) CAPM intercept; (2) Jensen's alpha; (3) practitioner "alpha" = any signal-driven excess return. Why it matters: The headline thing active managers claim to deliver — and the thing factor models try to explain away. Related: Beta, Jensen's alpha, Information ratio (IR), CAPM (Capital Asset Pricing Model)

Alpha capture

Domain: Trading Plain English: Systematic collection of analyst trade ideas — typically via licensed platforms like Marquee or Visible Alpha — used as inputs to multi-strat or quant overlay strategies. Why it matters: How sell-side research can be quantified and consumed as data. Related: Alt data, Multi-strat platforms

Alpha decay

Domain: Trading Plain English: The tendency of a profitable signal to lose its edge over time as it becomes known, crowded, or arbitraged away. Often modeled as exponential decay with a half-life. Why it matters: Forces strategies to refresh and explains why historical backtests overestimate live performance. Related: Capacity (of a strategy), Factor crowding, Lopez de Prado

Alt data

Domain: Trading Plain English: Non-traditional datasets — satellite imagery, credit card panel data, web scrapes, app installs, geolocation, sensor data, sentiment — used as inputs to investment signals. Why it matters: Major growth area for quant funds and platforms; bears regulatory and ethical risks (MNPI, privacy). Related: Sentiment data, RavenPack, FinBERT

AMM (Automated Market Maker)

Domain: Trading (crypto/DeFi) Plain English: On-chain exchange that quotes prices algorithmically from pooled inventory rather than from a limit order book. The pool's reserves and a deterministic bonding curve set the price. Uniswap, Curve, Balancer are leading examples. Why it matters: Foundational primitive of DeFi spot trading; replaces order-book exchanges in permissionless settings. Related: Constant product (AMM), Stableswap (Curve), Concentrated liquidity (Uniswap V3), Impermanent loss (divergence loss) See also: covered in 05-trading-theory-and-practice.md §Crypto/DeFi.

Anomaly

Domain: Trading Plain English: Empirical regularity in returns not explained by a standard asset-pricing model. Examples: value, momentum, low-vol, post-earnings drift. The "factor zoo" literature documents hundreds, many of which fail out-of-sample or after t-costs. Why it matters: Source of factor investing; centerpiece of the EMH-vs-behavioral debate. Related: Factor zoo, EMH (Efficient Market Hypothesis), Fama-French

Asset-backed security (ABS)

Domain: Trading Plain English: Bond whose cash flows come from a pool of underlying assets — auto loans, credit cards, student loans, mortgages. Mortgage-backed are usually broken out as MBS. Tranches divide cash flows by seniority. Why it matters: Major fixed-income asset class; central in the 2008 GFC narrative. Related: MBS (Mortgage-Backed Security), CDO (Collateralized Debt Obligation), Tranche

ATM offering

Domain: Trading Plain English: "At-the-market" equity offering: a public company sells shares directly into the secondary market over time at prevailing prices, via a broker. Less disruptive than a follow-on but caps the speed of issuance. Why it matters: Common funding tool for biotech and other capital-hungry issuers. Related: Follow-on, Secondary offering, IPO

Asset swap

Domain: Trading Plain English: Package trade: buy a bond (often a corporate) and enter an interest-rate swap to convert its fixed coupons to floating. The resulting "asset swap spread" isolates the bond's credit and liquidity components. Why it matters: Cleaner relative-value tool than YTM for credit; used in basis trades. Related: Swap spread, Z-spread, OAS (Option-Adjusted Spread)

ATS (Alternative Trading System)

Domain: Trading Plain English: SEC-regulated non-exchange trading venue. Includes Dark pools and ECN (Electronic Communications Network)s; subject to Reg ATS disclosure and fair-access rules. Why it matters: Bulk of off-exchange equity trading happens through ATSs. Related: Dark pool, ECN (Electronic Communications Network), Lit vs dark venue

AUM (Assets Under Management)

Domain: Trading Plain English: Total market value of assets a manager invests on behalf of clients. Standard scale metric. Doesn't capture leverage or strategy mix. Why it matters: Industry headline number; affects fee economics and capacity. Related: NAV (Net Asset Value), Capacity (of a strategy)

Backtesting

Domain: Trading Plain English: Simulating a trading strategy on historical data to estimate hypothetical performance. Plagued by lookahead bias, survivorship bias, data snooping, and t-cost neglect. López de Prado's purged k-fold and combinatorial purged CV are responses. Why it matters: Necessary but easy to overstate; the most common source of self-deception in quant work. Related: Walk-forward analysis, Purged k-fold CV, Deflated Sharpe ratio (Bailey-López de Prado)

Backwardation

Domain: Trading Plain English: Futures curve sloping downward — front contracts more expensive than later ones. Holders of long positions earn positive Roll yield as contracts roll up. Common in commodities with supply tightness. Why it matters: Drives carry returns in commodity strategies and the structure of VIX futures trades. Related: Contango, Roll yield, Basis (futures − spot)

Base fee (EIP-1559)

Domain: Trading (crypto) Plain English: Algorithmic per-block fee on Ethereum, burned (not paid to miners/validators), adjusted up or down based on whether the previous block was over/under-full. Introduced August 2021. Why it matters: Changed Ethereum gas-fee economics and reduced the burn of supply. Related: Gas, Priority fee (Ethereum), Blob (EIP-4844)

Basis (futures − spot)

Domain: Trading Symbol / formula: basis = F − S Plain English: Difference between a futures price and the underlying spot price. Reflects financing cost, dividends or yield, storage, convenience yield. Drives Cash-and-carry arbitrage arbitrage. Why it matters: Central to commodity, fixed income, and crypto futures trading. Related: Contango, Backwardation, Treasury basis trade

Basis (general)

Domain: Trading Plain English: In trading parlance, "basis" can mean: (1) futures − spot (above); (2) any spread between two related instruments (TIPS-Treasury basis, swap-Treasury basis, CDS-bond basis); (3) one basis point = 1/100 of a percent. Always specify which. Related: Basis point (bp), Treasury basis trade, TIPS Treasury basis

Basis point (bp)

Domain: Trading Plain English: 1/100 of one percent (0.01%). Standard unit for fixed-income yields, fees, and small return differences. 25bp = 0.25%. Related: Yield (curve, spread, etc.)

Beta

Domain: Trading (CAPM); Multi Symbol / formula: β_i = Cov(R_i, R_m) / Var(R_m) Plain English: In CAPM, the sensitivity of an asset's return to the market return. Beta > 1 is "high-beta" (more cyclical), <1 is defensive. Three distinct uses across this glossary: (a) trading: CAPM/factor beta; (b) econometrics: regression slope coefficient; (c) macro: subjective discount factor in DSGE. Why it matters: Bedrock of factor models, hedging, and risk decomposition. Related: CAPM (Capital Asset Pricing Model), Alpha, Betting against beta (BAB), Fama-French

Betting against beta (BAB)

Domain: Trading (factor) Plain English: Frazzini-Pedersen factor: long low-beta assets, short high-beta, levered to match unit beta. Premium attributed to leverage-constrained investors who reach for return by buying high-beta names. Empirically large but capacity-limited. Why it matters: Workhorse factor; underlies low-vol investing and many risk-parity tilts. Related: Low-vol, CAPM (Capital Asset Pricing Model), Fama-French

Bid-ask spread

Domain: Trading Plain English: Difference between the best ask (lowest sell offer) and best bid (highest buy bid). A direct transaction cost for a small marketable order; decomposes into order-processing, inventory, and adverse-selection components. Why it matters: Most basic measure of trading liquidity. Related: NBBO (National Best Bid and Offer), Mid (price), Adverse selection (market making), Kyle model

Binomial tree

Domain: Trading Plain English: Cox-Ross-Rubinstein discrete-time option pricing model. At each step the underlying moves up or down by a fixed factor; the option price is computed by backward induction with risk-neutral probabilities. Converges to Black-Scholes as steps shrink. Why it matters: Workhorse for pricing American options and intuition-building. Related: Trinomial tree, Black-Scholes-Merton formula, Risk-neutral pricing

Black-76

Domain: Trading Plain English: Black's 1976 formula for pricing options on futures and forwards. Differs from Black-Scholes in that the underlying is a futures price (no drift under risk-neutral measure). Widely used for interest-rate caps, swaptions, and commodity options. Why it matters: Standard for forward-based derivatives. Related: Black-Scholes-Merton formula, Swaption, Cap and floor (cap-floor / interest rate)

Black-Litterman model

Domain: Trading Plain English: Portfolio construction approach that combines market-implied "equilibrium" returns with the investor's explicit views and confidence levels. Produces more reasonable allocations than direct mean-variance optimization on noisy expected-return estimates. Why it matters: Practical fix for the well-known instability of Mean-variance portfolios. Related: Mean-variance, Markowitz, Robust optimization

Black-Scholes-Merton formula

Domain: Trading Symbol / formula: C = S·N(d1) − K·e^(−rτ)·N(d2), d1 = (ln(S/K) + (r + σ²/2)·τ)/(σ√τ), d2 = d1 − σ√τ Plain English: Closed-form 1973 formula for the price of a European call (and put, via parity) on a non-dividend stock under geometric Brownian motion. Assumes constant vol, no jumps, continuous trading, no transaction costs — all known to fail. Still the lingua franca of options markets. Why it matters: Foundational; even traders who don't use the model use its Greeks and implied vol. Related: Implied volatility (IV), Greeks (options Greeks), Put-call parity, Local vol

Blob (EIP-4844)

Domain: Trading (crypto) Plain English: "Proto-danksharding" data blobs introduced on Ethereum in March 2024 (Dencun upgrade). Provide cheap, temporary data availability for L2 rollups; cut L2 transaction costs by roughly an order of magnitude. Why it matters: Massively reduced rollup fees; central to the rollup-centric roadmap. Related: L2 (Layer 2), Optimistic rollup, zk-rollup, Rollup-centric roadmap

Bond

Domain: Trading Plain English: Debt security: borrower pays periodic coupons and returns face value at maturity. Sub-types include sovereigns, corporates, munis, agency, supranational; ratings split investment-grade and high-yield. Why it matters: Single largest asset class globally. Related: Treasury, Corporate bond, Yield (curve, spread, etc.), Duration (Macaulay / modified)

Builder (Ethereum / PBS)

Domain: Trading (crypto) Plain English: An entity that constructs candidate Ethereum blocks (selecting and ordering transactions) and bids them to proposers via MEV-Boost or other relays. Part of the Builder (Ethereum / PBS) architecture. Why it matters: Builders capture much of the MEV; their concentration is a major policy concern. Related: Builder (Ethereum / PBS), MEV-Boost, Searcher (MEV), Proposer (Ethereum)

Calmar ratio

Domain: Trading Symbol / formula: Calmar = annualized return / |maximum drawdown| Plain English: Risk-adjusted return metric using max drawdown as the risk measure (instead of σ as in Sharpe). Popular among CTAs and trend followers. Related: Sharpe ratio, Sortino ratio, Max drawdown, Ulcer index

CAPM (Capital Asset Pricing Model)

Domain: Trading Symbol / formula: E[R_i] = R_f + β_i·(E[R_m] − R_f) Plain English: Sharpe-Lintner one-factor asset pricing model: expected excess return equals beta times the market risk premium. Empirically rejected as a complete description but kept as a baseline. Why it matters: Conceptual anchor for cost of equity, beta-hedging, and factor models. Related: Security market line, Beta, Fama-French, MPT (Modern Portfolio Theory)

Carry

Domain: Trading Plain English: Return earned from simply holding a position, before any price change — coupon, dividend, interest differential, roll yield. "Carry trade" = funding low-yield, investing high-yield. Cross-asset carry is one of the four most documented factor premia. Why it matters: Major driver in FX, commodities, fixed income. Related: Carry trade (FX), Roll yield, Factor models (Fama-French and successors)

Cash-and-carry arbitrage

Domain: Trading Plain English: Buy spot, sell futures, finance the position with repo, deliver into the futures at expiry. Locks in the basis (futures minus spot minus financing). Drives the Treasury basis trade and crypto perp/spot basis. Why it matters: Workhorse arbitrage that disciplines futures pricing. Related: Basis (futures − spot), Treasury basis trade, Funding rate (perp / funding-rate-crypto)

CDS (Credit Default Swap)

Domain: Trading Plain English: Bilateral contract in which the buyer pays a periodic spread and receives a payment if a reference entity defaults. Functions as insurance against credit risk; trades as a directional credit instrument too. Notionals are large; standardized via ISDA documentation. Why it matters: Liquid credit-risk benchmark; central in the GFC narrative. Related: Itraxx / CDX, Itraxx / CDX, Credit spread, Capital structure arbitrage (capital-structure-arb)

CEX-DEX arbitrage

Domain: Trading (crypto) Plain English: Strategy that exploits price discrepancies between centralized exchanges (CEX, e.g., Binance, Coinbase) and decentralized AMMs (DEX, e.g., Uniswap). Often executed by searchers using flash loans and atomic transactions. Why it matters: Major source of MEV on Ethereum and L2s. Related: MEV (Maximal Extractable Value), Searcher (MEV), AMM (Automated Market Maker)

Chainlink

Domain: Trading (crypto) Plain English: Decentralized Oracle network providing price feeds and other off-chain data to smart contracts. Aggregates data from many nodes/sources; widely used by DeFi protocols. Why it matters: Most-used oracle in DeFi; outages or manipulations have caused historical incidents. Related: Oracle, TWAP oracle

Closed-end fund (CEF)

Domain: Trading Plain English: Investment fund with a fixed number of shares trading on an exchange. Shares can trade at premiums or discounts to NAV; the discount itself is a tradable phenomenon. Why it matters: Persistent NAV discount is a classic limits-to-arbitrage puzzle. Related: Creation / redemption (ETF), Mutual fund, NAV (Net Asset Value)

Cointegration

Domain: Trading (econometrics) Plain English: Two or more non-stationary series whose linear combination is stationary. Underlies pairs trading and mean-reverting relative-value strategies. Why it matters: Statistical foundation of pair/stat-arb strategies and many term-structure analyses. Related: Engle-Granger, Johansen test, Pairs trading

Combinatorial purged CV

Domain: Trading (ML) Plain English: López de Prado's cross-validation scheme for financial data: across multiple train-test splits, purge observations whose labels overlap with the test set and apply an embargo to avoid lookahead. Aggregates results across combinatorial paths. Why it matters: Reduces overfitting in ML for finance; preferred over naive k-fold for time-series data. Related: Purged k-fold CV, Backtesting, Walk-forward analysis

Concentrated liquidity (Uniswap V3)

Domain: Trading (crypto) Plain English: AMM design where LPs allocate capital to specific price ranges rather than the full price curve. Inside the chosen range, liquidity is much deeper; outside, the LP holds 100% of one token. Introduced May 2021 in Uniswap V3. Why it matters: Dramatically improved AMM capital efficiency for stable pairs; reshaped market making. Related: AMM (Automated Market Maker), Constant product (AMM), Tick (Uniswap V3 / tick-uniswap), Range order

Constant product AMM

Domain: Trading (crypto) Symbol / formula: x · y = k Plain English: Uniswap V1/V2 bonding curve: reserves x and y are kept on a hyperbola of constant product. Price = y/x. Slippage rises with trade size relative to reserves. Why it matters: Simplest and most-copied AMM design. Related: Stableswap (Curve), Concentrated liquidity (Uniswap V3), AMM (Automated Market Maker)

Contango

Domain: Trading Plain English: Futures curve sloping upward — later contracts more expensive than near ones. Holders of long positions earn negative Roll yield as the curve rolls down. Persistent contango is the dominant state for VIX futures. Why it matters: Drives the long-run drag in volatility ETPs (VXX) and many commodity ETFs (USO). Related: Backwardation, Roll yield, Basis (futures − spot)

Convexity

Domain: Trading Plain English: Second-derivative sensitivity of a bond's price to yield (or any instrument to its risk factor). Positive convexity = price rises more for a yield drop than it falls for an equal yield rise. Options have convexity (gamma). Why it matters: Drives gamma-hedging needs, the dynamics of MBS hedging, and the "convexity rally" in Treasuries when rates fall sharply. Related: Duration (Macaulay / modified), Gamma, MBS (Mortgage-Backed Security)

CoW Protocol

Domain: Trading (crypto) Plain English: DEX aggregator that batches user orders and runs periodic batch auctions; solvers compete to provide the best execution including coincidence-of-wants matches between users (no AMM needed) and DEX/CEX paths. Aims to reduce MEV exposure. Why it matters: Leading example of intent-based, solver-driven trading. Related: Intent-based trading, Solver, Batch auction, OFA (Order Flow Auction)

Credit spread

Domain: Trading Plain English: Yield gap between a credit-risky bond and a risk-free reference of the same maturity. Components: expected default loss, credit risk premium, liquidity premium, tax differences. Measures include G-spread, Z-spread, OAS, asset-swap spread. Why it matters: Headline pricing of credit risk; macro indicator of risk appetite. Related: Z-spread, OAS (Option-Adjusted Spread), Asset swap, HY vs IG

Creation / redemption (ETF)

Domain: Trading Plain English: Authorized Participants (APs) can create new ETF shares by delivering a basket of the underlying securities to the ETF issuer, or redeem ETF shares for the basket. This in-kind arbitrage keeps ETF prices close to NAV. Why it matters: Engine of ETF tax efficiency and tight NAV tracking. Related: ETF arbitrage, Creation / redemption (ETF), NAV (Net Asset Value)

CTD (Cheapest to Deliver)

Domain: Trading Plain English: For a deliverable bond futures contract (Treasury futures), the bond in the deliverable basket that is most economical for the short to deliver, after accounting for conversion factors. The CTD effectively prices the futures. Why it matters: Critical for hedge ratios, basis trades, and squeeze risk. Related: Treasury basis trade, Basis (futures − spot), Conversion factor (futures)

Dark pool

Domain: Trading Plain English: ATS that does not publicly display its order book. Designed to allow large orders to trade without signaling intent. Subject to Reg ATS disclosures and SEC surveillance. Why it matters: Off-exchange volume now exceeds 40% of U.S. equity trading; controversial because of price-discovery and equal-access concerns. Related: ATS (Alternative Trading System), Lit vs dark venue, IEX speed bump, Internalization

Deflated Sharpe ratio (Bailey-López de Prado)

Domain: Trading Plain English: Sharpe ratio adjusted for the number of trials, the skewness/kurtosis of returns, and the sample size. Tells you whether an observed Sharpe is likely to reflect real skill or selection bias from many backtests. Why it matters: Antidote to backtest data mining; rarely computed by practitioners but increasingly demanded by allocators. Related: Sharpe ratio, Backtesting, Multiple testing

Deep hedging

Domain: Trading (ML) Plain English: Buehler et al. framework using neural networks to learn optimal hedging strategies under realistic frictions (transaction costs, market impact, discrete time) without assuming a specific model for the underlying. Trained via simulation or historical data. Why it matters: Bridges traditional derivatives pricing with modern ML; gaining traction at large dealers. Related: Black-Scholes-Merton formula, Reinforcement learning (execution), Stochastic vol (Heston, SABR)

Delta

Domain: Trading (options) Symbol / formula: Δ = ∂V/∂S Plain English: Sensitivity of an option's price to a $1 change in the underlying. Calls have positive delta (0 to 1), puts negative (−1 to 0). Used to delta-hedge. Why it matters: First Greek you compute; primary hedge ratio. Related: Gamma, Greeks (options Greeks), Delta hedge

Direct listing

Domain: Trading Plain English: Going-public method in which existing shares start trading directly on an exchange without raising new capital and without traditional underwriting. Used by Spotify (2018), Slack, Coinbase. NYSE permits primary direct listings (raising capital). Why it matters: Alternative to IPO that bypasses underwriter pricing and lockups; favored by cash-rich, well-known issuers. Related: IPO, SPAC (Special Purpose Acquisition Company), Follow-on

Discount (in finance)

Domain: Trading; Multi Plain English: Three distinct uses: (1) trade at a discount = price below par or below NAV (closed-end fund, distressed bond); (2) discount rate in DCF = rate at which future cash flows are converted to present value; (3) Fed discount rate = primary credit rate at the discount window. Always disambiguate. Related: DCF (Discounted Cash Flow), Present value, Primary credit rate

Discretionary macro

Domain: Trading (practitioner archetype) Plain English: Hedge-fund style in which a PM takes large directional bets on rates, FX, equities, and commodities based on judgment about the macro cycle. Soros, Druckenmiller, Tudor, modern Brevan Howard, Caxton. Related: Systematic macro, CTA (Commodity Trading Advisor / managed futures), Multi-strat platforms

Dispersion trade

Domain: Trading Plain English: Sell index volatility (e.g., SPX vol), buy single-stock volatility on the constituents, in weights that roughly cancel net volatility exposure. Profits when correlation falls (single-stock vol stays high while index vol drops). Hit hard during episodes of "all-up-together" risk-on. Why it matters: Workhorse vol-arb strategy; reflects implied correlation pricing. Related: Variance swap, Implied correlation, Vol skew

dYdX

Domain: Trading (crypto) Plain English: Decentralized perpetual swap exchange; v4 (Cosmos app-chain, 2023) uses an order book rather than an AMM. Among the largest perp DEXs by volume. Related: Perpetual swap (perp), GMX / GLP, Hyperliquid

Duration (Macaulay / modified)

Domain: Trading Symbol / formula: D_mod = −(1/P)·dP/dy Plain English: Sensitivity of a bond's price to yield. A 1bp yield rise reduces a 7-year-duration bond's price by ~7bp. Macaulay duration is a weighted average of cash-flow times; modified duration adjusts for compounding. Why it matters: Standard risk measure for fixed income; central to the SVB-style "duration risk" of long bonds funded by short deposits. Related: Convexity, Bond, Duration risk

Duration risk

Domain: Trading / Multi Plain English: Risk that long-duration asset values fall when rates rise. SVB (March 2023) held large HTM long Treasuries and MBS purchased at low yields; when rates rose, mark-to-market losses combined with deposit flight forced realization. Standard banking ALM topic newly salient post-2022. Why it matters: Centerpiece of the 2023 regional-bank crisis and ongoing supervisory focus. Related: Duration (Macaulay / modified), HTM vs AFS (Held-to-Maturity vs Available-for-Sale), SVB-style duration risk

DvP (Delivery vs Payment)

Domain: Trading Plain English: Settlement mechanism in which delivery of a security occurs if and only if payment occurs. Eliminates principal risk. Why it matters: Standard for modern securities settlement. Related: T+1 (T plus 1), T+2 (T plus 2), CCP (Central Counterparty), DTCC (Depository Trust & Clearing Corporation)

ECN (Electronic Communications Network)

Domain: Trading Plain English: Electronic order-matching venue that displays orders and matches them automatically. Subset of ATS (Alternative Trading System); pioneered tighter spreads and faster execution in the 1990s. Related: ATS (Alternative Trading System), Dark pool

EIP-1559

Domain: Trading (crypto) Plain English: Ethereum upgrade (August 2021) introducing a Base fee (EIP-1559) (burned) and an optional Priority fee (Ethereum) (tip to validator). Replaced the prior first-price auction for gas. Why it matters: Changed fee dynamics and made ETH supply potentially deflationary under high usage. Related: Base fee (EIP-1559), Priority fee (Ethereum), Gas

EMH (Efficient Market Hypothesis)

Domain: Trading Plain English: Fama's hypothesis that asset prices fully reflect available information, so it's impossible to earn excess risk-adjusted returns from that information. Three forms: weak (prices reflect past prices), semi-strong (all public info), strong (all public + private info). Always tested jointly with an asset pricing model — Fama's "joint hypothesis problem." Why it matters: Single most-debated proposition in finance; anchors all academic asset-pricing work. Related: Joint hypothesis problem, Anomaly, CAPM (Capital Asset Pricing Model)

Equity long/short (L/S)

Domain: Trading (practitioner archetype) Plain English: Hedge fund style with both long and short positions in equities. Variants range from market-neutral (zero net exposure) to directional (e.g., 130/30 funds). Related: Market neutral, Multi-strat platforms, Pod shop

Equity market neutral

Domain: Trading Plain English: Long/short equity portfolio with explicit zero net market exposure (beta-neutral, dollar-neutral). Aims to isolate cross-sectional alpha. Often factor-neutral as well. Related: Equity long-short, Stat arb (statistical arbitrage), Pairs trading

ETF (Exchange-Traded Fund)

Domain: Trading Plain English: Investment fund that trades intraday on an exchange like a stock, with creation/redemption keeping the share price close to NAV. Universe spans equity indices, bonds, commodities, leveraged/inverse, active, and (since 2024) spot bitcoin. Related: Creation / redemption (ETF), ETF arbitrage, NAV (Net Asset Value)

ETF arbitrage

Domain: Trading Plain English: Authorized Participants buy/sell the underlying basket and create/redeem ETF shares to capture deviations between ETF price and NAV. Disciplines tracking errors but breaks down in fast markets (March 2020 bond ETFs). Related: Creation / redemption (ETF), Creation / redemption (ETF), Premium vs NAV

Event-driven

Domain: Trading (practitioner archetype) Plain English: Hedge-fund style trading around corporate events — mergers, spinoffs, bankruptcies, restructurings, regulatory decisions. Includes Merger arb, Distressed (hedge fund strategy), special situations. Related: Merger arb, Distressed (hedge fund strategy), Special situations

Expected shortfall (ES / CVaR)

Domain: Trading Plain English: Average loss in the worst α% of outcomes (the tail beyond the VaR cutoff). Coherent risk measure; unlike VaR, it accounts for the magnitude of tail losses. Basel FRTB replaced VaR with ES for trading-book capital. Why it matters: Increasingly the regulatory and risk-management standard. Related: VaR (Value at Risk), FRTB (Fundamental Review of the Trading Book), Stress testing

Factor crowding

Domain: Trading Plain English: Many investors holding similar factor exposures; when they need to unwind simultaneously, prices move sharply against the factor (cf. August 2007 quant quake, August 2024 yen-carry unwind). Various metrics: factor correlation, factor turnover, crowding scores from MSCI/SocGen. Why it matters: Major risk in the post-2010 "factor zoo" era. Related: Factor zoo, Factor timing, Quant quake

Factor models (Fama-French and successors)

Domain: Trading Plain English: Regression-based asset-pricing models that explain cross-sectional return variation with a small set of factors. Fama-French 3 (market, size SMB (Small Minus Big), value HML (High Minus Low)) → Carhart 4 (+ momentum MOM (momentum factor)) → Fama-French 5 (+ profitability RMW / CMA, investment RMW / CMA) → q-factor (Hou-Xue-Zhang) → many more. Why it matters: Workhorse framework for evaluating active managers and constructing systematic strategies. Related: HML (High Minus Low), SMB (Small Minus Big), MOM (momentum factor), RMW / CMA, RMW / CMA, Fama-French, Hou-Xue-Zhang (q-factor model), Hou-Xue-Zhang (q-factor model)

Factor zoo

Domain: Trading Plain English: Cochrane's term for the proliferation of "factors" claimed in the empirical asset-pricing literature (hundreds by 2015, growing). Many fail out-of-sample, after t-costs, or after correcting for multiple testing (Harvey-Liu-Zhu 2016). Why it matters: Sets the bar for what counts as a real factor and motivates Deflated Sharpe ratio (Bailey-López de Prado). Related: Anomaly, Deflated Sharpe ratio (Bailey-López de Prado), Multiple testing

Fair value

Domain: Trading Plain English: Theoretical price of an instrument under a model — e.g., futures fair value = spot · e^(r·τ) − PV(dividends). Often quoted alongside market price to highlight rich/cheap. Related: Basis (futures − spot), Arbitrage-free pricing

Fed funds (effective rate)

Domain: Trading / Macro Plain English: See Effective Federal Funds Rate (EFFR).

Fill rate / cancel rate

Domain: Trading Plain English: Fill rate = fraction of submitted limit orders that get executed; cancel rate = fraction canceled before execution. Microstructure quality metrics, with regulatory attention to extreme cancel/order ratios (potential indicia of Quote stuffing). Related: Queue position, Adverse selection (market making), HFT (High-Frequency Trading)

FinBERT

Domain: Trading (ML) Plain English: BERT-style language model fine-tuned on financial text (analyst reports, news, filings) for sentiment classification and named-entity recognition. Widely used as a feature in NLP-driven signals. Related: Sentiment data, Alt data

Fixed income relative value (RV)

Domain: Trading (practitioner archetype) Plain English: Hedge-fund style that trades small mispricings across closely related fixed-income instruments — on-the-run vs off-the-run, swap-Treasury, TIPS-Treasury, futures-cash basis. Typically very high leverage and small per-trade edges. Why it matters: Source of the 2020 March basis-trade blowups and the 2025 Treasury basis-trade scrutiny. Related: Treasury basis trade, Swap spread, On-the-run vs off-the-run

Flashbots

Domain: Trading (crypto) Plain English: Research and infrastructure organization that built MEV-Boost, the dominant relay between Ethereum proposers and builders. Aims to reduce harmful MEV externalities and increase transparency. Related: MEV-Boost, Builder (Ethereum / PBS), Builder (Ethereum / PBS)

Forward (contract)

Domain: Trading Plain English: OTC bilateral agreement to buy/sell an asset at a future date for a price fixed today. Like a future but customized and bilateral (no exchange clearing). Used heavily in FX. Related: Future (futures contract), Swap (interest rate / swap-interest-rate), FRA (Forward Rate Agreement)

FRA (Forward Rate Agreement)

Domain: Trading Plain English: OTC contract that fixes a future interest rate. A 3x6 FRA fixes the 3-month rate that will prevail 3 months from now. Settled in cash on the difference vs realized rate. Related: Swap (interest rate / swap-interest-rate), OATs OIS (spread), Swaption

Front-running

Domain: Trading Plain English: Trading ahead of a known client order to profit from the expected price impact. Illegal for brokers in U.S. and most major markets. In crypto, "front-running" often refers to MEV searchers reordering pending public mempool trades. Related: MEV (Maximal Extractable Value), Sandwich attack, PFOF (Payment for Order Flow)

FRTB (Fundamental Review of the Trading Book)

Domain: Trading (regulation) Plain English: Basel post-crisis trading-book capital framework: replaces 10-day 99% VaR with Expected shortfall (ES / CVaR) at 97.5%, introduces non-modellable risk factor capital, and tightens the boundary between trading and banking books. Phased into effect mostly 2024–25. Why it matters: Major change to bank trading-book capital; affects bank market-making capacity. Related: Expected shortfall (ES / CVaR), Basel III / IV, VaR (Value at Risk)

Funding rate (perp / funding-rate-crypto)

Domain: Trading (crypto) Plain English: Periodic payment between long and short holders of a perpetual swap to anchor the perp price to the spot index. When perps trade above spot (positive funding), longs pay shorts and vice versa. Usually paid every 8 hours; sometimes hourly. Why it matters: The mechanism that makes Perpetual swap (perp)s "perpetual"; also a market sentiment gauge. Related: Perpetual swap (perp), Basis (futures − spot), Cash-and-carry arbitrage

Future (futures contract)

Domain: Trading Plain English: Exchange-traded, standardized agreement to buy/sell an asset at a future date for a price fixed today. Marked to market daily through a CCP (Central Counterparty). Listed on commodities, equities, bonds, FX, and now crypto. Related: Forward (contract), Basis (futures − spot), CCP (Central Counterparty)

Gamma

Domain: Trading (options) Symbol / formula: Γ = ∂²V/∂S² = ∂Δ/∂S Plain English: Rate of change of Delta with respect to underlying price. Long options have positive gamma (you get longer as the market rises, shorter as it falls); short options have negative gamma. Drives intraday hedging flows. Why it matters: Negative-gamma dealer positioning amplifies moves; positive amplifies but in the opposite direction (mean-reverting hedging). Related: Delta, Greeks (options Greeks), Gamma squeeze, Vanna / charm / vomma

Gamma squeeze

Domain: Trading Plain English: Sharp price spike in an underlying when a large open interest in OTM calls forces dealers to delta-hedge by buying the underlying, pushing price further up, requiring more buying, etc. GME (Jan 2021) is the textbook case. Why it matters: Recurring meme-stock and 0DTE phenomenon; spotlight on dealer-positioning data. Related: Gamma, Greeks (options Greeks), Meme stock

Gas

Domain: Trading (crypto) Plain English: Computational metering unit on Ethereum and EVM chains. Each opcode consumes gas; users pay gas × gas price for execution. Total = base fee + priority fee (post EIP-1559). Related: Base fee (EIP-1559), Priority fee (Ethereum), Gas wars

Gas wars

Domain: Trading (crypto) Plain English: Bidding contests for transaction inclusion or position in a block, driving priority fees sky-high during high-demand events (NFT mints, MEV opportunities). Mitigated post-EIP-1559 but still occur. Related: MEV (Maximal Extractable Value), Priority fee (Ethereum), Base fee (EIP-1559)

Glosten-Milgrom model

Domain: Trading (microstructure) Plain English: 1985 model in which a market maker sets bid and ask quotes such that expected profit is zero given a mix of informed and uninformed traders. The bid-ask spread compensates for adverse selection from informed flow. Foundational alongside the Kyle model. Why it matters: First-principles explanation of why spreads exist. Related: Kyle model, Bid-ask spread, Adverse selection (market making)

GMX / GLP

Domain: Trading (crypto) Plain English: GMX is a perp DEX on Arbitrum/Avalanche where traders take leveraged positions against the GLP pool (a basket of crypto held by liquidity providers). LPs earn fees but absorb trader P&L. Why it matters: Pioneered the LP-as-counterparty model in DeFi perps. Related: Perpetual swap (perp), dYdX, Hyperliquid

Greeks (options Greeks)

Domain: Trading (options) Plain English: First and higher-order sensitivities of an option's price to its inputs. First-order: Delta (spot), Vega (vol), Theta (time), Rho (rates). Second-order: Gamma (∂Δ/∂S), Vanna / charm / vomma (∂Δ/∂σ), Vanna / charm / vomma (∂vega/∂σ), Vanna / charm / vomma (∂Δ/∂τ). Why it matters: Day-to-day language of options trading and hedging. Related: Delta, Gamma, Vega, Theta, Rho, Vanna / charm / vomma, Vanna / charm / vomma

HFT (High-Frequency Trading)

Domain: Trading Plain English: Proprietary trading characterized by sub-millisecond response times, very high message rates, very short position holding times, and large daily volumes. Strategies include market making, latency arb, statistical arb. Citadel Securities, Virtu, Jane Street, Hudson River, Jump are leading firms. Why it matters: Dominates U.S. equity, options, and futures volume; central in microstructure regulation debates. Related: Adverse selection (market making), Latency arbitrage, Colocation, Microwave links

Hierarchical risk parity (HRP)

Domain: Trading Plain English: López de Prado's portfolio-construction approach: cluster assets via hierarchical clustering on correlations, then allocate risk recursively down the tree. Avoids the matrix-inversion instability of mean-variance and Markowitz. Why it matters: Practical alternative to mean-variance for high-dimensional allocation. Related: Mean-variance, Markowitz, Risk parity, Lopez de Prado

Hyperliquid

Domain: Trading (crypto) Plain English: High-performance perp DEX on its own L1 with an on-chain order book; among the fastest-growing in 2024–25 by volume and listed token (HYPE). Related: Perpetual swap (perp), dYdX, GMX / GLP

IEX speed bump

Domain: Trading Plain English: IEX exchange introduced a deliberate 350-microsecond delay on incoming orders to neutralize speed advantages from colocated HFTs picking off slow quotes. Now copied in modified forms by other venues. Why it matters: Microstructure innovation that re-shaped debates about market quality. Related: Latency arbitrage, HFT (High-Frequency Trading), Colocation

Impermanent loss (divergence loss)

Domain: Trading (crypto) Plain English: Loss an AMM LP suffers when the relative prices of pool tokens move, versus simply holding the same tokens outside the pool. Only "impermanent" if prices revert; otherwise realized at withdrawal. Better named Impermanent loss (divergence loss). Why it matters: Major hidden cost of AMM LPing, often masked by trading-fee yield. Related: AMM (Automated Market Maker), Concentrated liquidity (Uniswap V3), LP token

Implementation shortfall (IS)

Domain: Trading Plain English: Perold's measure of execution cost: difference between the value of the paper portfolio (priced at the decision time) and the actual portfolio value after execution. Captures market impact, opportunity cost, fees, and timing. Why it matters: Gold-standard execution metric; underlies the IS algo family. Related: IS algorithm (Implementation Shortfall), Almgren-Chriss model, Market impact

Implied correlation

Domain: Trading Plain English: Correlation among index constituents that's consistent with observed index option prices and single-stock option prices. Inputs to dispersion-trade pricing. Related: Dispersion trade, Variance swap

Implied volatility (IV)

Domain: Trading Plain English: The volatility input that, plugged into Black-Scholes (or another model), reproduces an observed option price. A market price of volatility, not a forecast. The IV surface varies by strike (smile/skew) and maturity (term structure). Why it matters: Defines the options market; benchmark for vol forecasting, hedging, and trading. Related: Vol smile / skew, Vol skew, VIX, Black-Scholes-Merton formula

Information ratio (IR)

Domain: Trading Symbol / formula: IR = (R_p − R_b) / σ(R_p − R_b) Plain English: Active return per unit of active risk (tracking error). Standard skill metric for active managers benchmarked to an index. Why it matters: Sharpens Sharpe ratio for benchmark-relative funds. Related: Tracking error, Active share, Sharpe ratio

Intent-based trading

Domain: Trading (crypto) Plain English: Architectural pattern in which users sign declarative "intents" (e.g., "swap up to 10 ETH for at least 30,000 USDC by 5pm") and competing solvers find execution paths. Distinguishes "what I want" from "how to execute it." CoW, UniswapX, Across. Why it matters: Active research and engineering front in DeFi; reshapes MEV and venue competition. Related: CoW Protocol, Solver, OFA (Order Flow Auction)

IORB

Domain: Trading / Macro Plain English: See IORB (Interest on Reserve Balances) in macro section.

IPO

Domain: Trading Plain English: Initial Public Offering: first sale of equity to public investors, usually underwritten by investment banks. Allocations to institutional accounts at the offering price; trading begins on the exchange. Related: Direct listing, SPAC (Special Purpose Acquisition Company), Follow-on

Itraxx / CDX

Domain: Trading Plain English: Standardized credit-default-swap indices. ITRAXX covers European names; CDX covers North America. Subdivided by IG, HY, sector. Liquid hedge for credit portfolios. Related: CDS (Credit Default Swap), Credit spread

Jensen's alpha

Domain: Trading Symbol / formula: α = R_p − [R_f + β·(R_m − R_f)] Plain English: Realized return on a portfolio in excess of what CAPM would predict given its beta. Jensen 1968's original alpha measure for fund performance. Related: Alpha, CAPM (Capital Asset Pricing Model), Information ratio (IR)

Joint hypothesis problem

Domain: Trading Plain English: Fama's observation that any test of market efficiency is a joint test of efficiency and the assumed asset-pricing model. An anomaly might mean inefficient markets — or that the model is wrong. Why it matters: Cuts deep into all empirical EMH/anomaly debates. Related: EMH (Efficient Market Hypothesis), Anomaly, CAPM (Capital Asset Pricing Model)

Kelly criterion

Domain: Trading Symbol / formula: f* = (μ − r) / σ² (continuous, log utility) Plain English: Bet-sizing rule that maximizes the long-run geometric growth rate of capital. Full Kelly is volatile; practitioners typically use fractional Kelly (e.g., 25–50%) to reduce drawdowns. Why it matters: Most-cited theoretical bet-sizing prescription; underpins many systematic position-sizing rules. Related: Fractional Kelly, Position sizing, Risk budgeting

Kyle's lambda (kyle-lambda)

Domain: Trading (microstructure) Symbol / formula: λ = σ_v / (2·σ_u) (Kyle 1985 single-period) Plain English: Price impact per unit of order flow. The slope of the price-change vs net-order-flow regression. Empirical proxy for illiquidity and informed-trading intensity. Why it matters: Standard microstructure illiquidity measure. Related: Kyle model, Market impact, Bid-ask spread

Kyle model

Domain: Trading (microstructure) Plain English: 1985 model with a single informed trader, noise traders, and a competitive market maker who sets a single linear price as a function of total order flow. Generates Kyle's lambda (kyle-lambda) and explains price impact. Why it matters: Companion to Glosten-Milgrom model; the two together are the microstructure canon. Related: Glosten-Milgrom model, Kyle's lambda (kyle-lambda), Market impact

Last look

Domain: Trading (FX) Plain English: Practice in FX markets where a liquidity provider has a brief window after receiving an aggressive order to accept or reject it. Controversial because it lets LPs cherry-pick stale quotes. Why it matters: Subject of regulatory scrutiny (FX Global Code) and ongoing debate. Related: Adverse selection (market making), Adverse selection (market making)

Latency arbitrage

Domain: Trading Plain English: Profiting from price changes that one exchange has not yet incorporated, because you receive market data faster than slower participants and can pick off stale quotes. Often called "speed bump bait" by critics. Estimated by Aquilina-Budish-O'Neill (2022) to cost ~$5B/yr globally. Why it matters: Motivation for periodic batch auctions and IEX-style speed bumps. Related: HFT (High-Frequency Trading), IEX speed bump, Batch auction

Layering

Domain: Trading Plain English: Illegal market manipulation: place non-bona fide orders on one side of the book to create a false impression of supply/demand, then trade on the other side. Distinct from Spoofing in some classifications; both are prosecuted under U.S. Dodd-Frank. Related: Spoofing, Wash trading, Painting the tape

Liquidity (market liquidity)

Domain: Trading Plain English: Ability to trade quickly and at low cost without moving the price. Measured by spread, depth, resilience, price impact. Different from Funding liquidity (ability to fund positions). Related: Bid-ask spread, Kyle's lambda (kyle-lambda), Funding liquidity

Liquidity mining

Domain: Trading (crypto) Plain English: Protocol incentive program that pays governance tokens to users who provide liquidity. Bootstrapped DeFi summer (2020) and many subsequent launches; often produces unsustainable yields. Related: Yield farming, Governance token, ve-Token (vote-escrowed)

Local volatility

Domain: Trading (options) Plain English: Dupire's model in which volatility is a deterministic function of spot and time, calibrated to match the observed option-price surface exactly. Reproduces today's smile but generates unrealistic forward smile dynamics. Related: Stochastic vol (Heston, SABR), Implied volatility (IV), Vol smile / skew

LP token

Domain: Trading (crypto) Plain English: ERC-20 token representing an LP's share of an AMM pool. Can be used as collateral, staked for additional rewards, or composed across protocols. Related: AMM (Automated Market Maker), Yield farming, Liquidity mining

LRT (Liquid Restaking Token)

Domain: Trading (crypto) Plain English: Token representing a position in a restaking protocol (EigenLayer, Symbiotic), itself usually backed by LST (Liquid Staking Token)s. Adds another composability layer with attendant slashing and operator risks. EtherFi, Renzo, Kelp. Related: LST (Liquid Staking Token), Restaking (EigenLayer), Restaking (EigenLayer)

LST (Liquid Staking Token)

Domain: Trading (crypto) Plain English: Token representing a position in a liquid-staking protocol (Lido stETH, Rocket Pool rETH). Earns staking yield while remaining transferable and usable as DeFi collateral. Related: LRT (Liquid Restaking Token), Restaking (EigenLayer), Restaking (EigenLayer)

Market impact

Domain: Trading Plain English: Price movement caused by your own trading. Two components: temporary (price reverts after you stop) and permanent (information component, doesn't revert). Standard models: linear (Kyle's lambda (kyle-lambda)), square-root, Almgren-Chriss model. Why it matters: Major cost of large trades; centerpiece of execution analysis. Related: Kyle's lambda (kyle-lambda), Implementation shortfall (IS), Slippage

Market making

Domain: Trading Plain English: Standing ready to buy at the bid and sell at the ask, earning the spread minus inventory and adverse-selection costs. Now dominated by HFT firms in liquid markets; OTC dealers in less-liquid markets. Related: Bid-ask spread, Glosten-Milgrom model, HFT (High-Frequency Trading)

MBS (Mortgage-Backed Security)

Domain: Trading Plain English: Bond whose cash flows come from a pool of residential mortgages. Agency MBS (Ginnie/Fannie/Freddie) carry implicit/explicit U.S. guarantee; non-agency carry credit risk. Prepayment optionality makes effective duration and convexity highly state-dependent. Why it matters: Largest segment of U.S. bond market after Treasuries; central to MBS RV and dealer hedging. Related: MBS RV (Mortgage-Backed Securities Relative Value), Convexity, Duration (Macaulay / modified), Prepayment risk

Mean-variance optimization

Domain: Trading Plain English: Markowitz's framework: choose portfolio weights to minimize variance for a given expected return, or maximize Sharpe ratio. Notoriously unstable in practice because of estimation error in expected returns. Hence Black-Litterman model, Robust optimization, Hierarchical risk parity (HRP). Related: Markowitz, Efficient frontier, CAPM (Capital Asset Pricing Model)

MEV (Maximal Extractable Value)

Domain: Trading (crypto) Plain English: Profit a validator/builder can extract by reordering, including, or excluding transactions within a block. Includes Sandwich attacks, arbitrages, liquidations, NFT sniping. Roughly $700M+ extracted on Ethereum since 2020 per Flashbots metrics. Why it matters: Fundamental property of permissionless blockchains; key driver of architecture choices (PBS, MEV-Boost, OFA). Related: Builder (Ethereum / PBS), MEV-Boost, Sandwich attack, Searcher (MEV)

MEV-Boost

Domain: Trading (crypto) Plain English: Software run by Ethereum validators that outsources block construction to a marketplace of Builder (Ethereum / PBS)s via Relay (MEV)s, with the validator selecting the highest-bid block. Dominant post-Merge implementation of Builder (Ethereum / PBS). Why it matters: Used by >90% of Ethereum validators by 2024; centralization concern. Related: Builder (Ethereum / PBS), Builder (Ethereum / PBS), Flashbots, Proposer (Ethereum)

Merger arb

Domain: Trading (practitioner archetype) Plain English: Buying targets and shorting acquirers in announced deals, earning the deal spread (target price below offer) minus the cost of capital and risk of deal break. Related: Event-driven, Deal spread, Risk arb

MiFID II / MiFIR

Domain: Trading (regulation) Plain English: EU 2018 framework restructuring secondary markets — pre/post-trade transparency, unbundled research payments, best execution rules, systematic internalisers, double volume caps on dark trading. MiFIR is the directly applicable regulation; MiFID II the implementing directive. Why it matters: Defines European market structure; ongoing review process (MiFID III). Related: Regulation NMS, Best execution, Unbundling

Momentum (factor)

Domain: Trading (factor) Plain English: Jegadeesh-Titman 1993: stocks that have outperformed over the past 6–12 months tend to keep outperforming over the next 3–12 months. Robust across asset classes (cross-sectional and time-series). Subject to crashes during sharp reversals. Related: Fama-French, Carhart four-factor model, MOM (momentum factor), Time-series momentum

Money market fund (MMF)

Domain: Trading Plain English: Mutual fund investing in very short-term, high-quality debt (T-bills, repo, commercial paper, agency discount notes). Government MMFs hold only Treasuries/agency repo; prime MMFs add commercial paper. SEC reforms (2010, 2014, 2023) tightened liquidity requirements and added gates/fees. Why it matters: Huge channel into ON RRP and short-term financing markets; subject to run risk (2008 Reserve Primary, 2020 prime MMF stress). Related: ON RRP (Overnight Reverse Repo Facility), MMF reform, Gates and fees

MPT (Modern Portfolio Theory)

Domain: Trading Plain English: Markowitz's framework for portfolio choice: given assets' expected returns, variances, and covariances, diversification can reduce risk for any target return. Underlies Efficient frontier, CAPM (Capital Asset Pricing Model), and most subsequent finance theory. Related: Markowitz, Mean-variance, CAPM (Capital Asset Pricing Model)

Multi-strat platform

Domain: Trading (practitioner archetype) Plain English: Hedge-fund organization that allocates capital to dozens or hundreds of portfolio-manager "pods," each running a discrete strategy with hard risk budgets and drawdown stops. Examples: Citadel, Millennium, Point72, Balyasny, Schonfeld. Compete aggressively for talent. Why it matters: Dominant model in equity L/S and a growing share of macro/quant; widely studied for its risk management architecture. Related: Pod shop, Sleeve, Drawdown stop

NAV (Net Asset Value)

Domain: Trading Symbol / formula: NAV = (assets − liabilities) / shares Plain English: Per-share value of a fund's holdings. ETFs trade near NAV thanks to arbitrage; closed-end funds and listed real-estate vehicles can persistently diverge. Related: ETF arbitrage, Closed-end fund (CEF), Mark-to-market (MTM)

NBBO (National Best Bid and Offer)

Domain: Trading Plain English: Best bid and offer across all SIP-reporting U.S. equity venues. Reg NMS requires routing protected quotes to the NBBO. Quality and timeliness of the SIP feed are perennial regulatory issues. Why it matters: Reference price for retail execution and many algos. Related: Regulation NMS, Order Protection Rule, PFOF (Payment for Order Flow)

OAS (Option-Adjusted Spread)

Domain: Trading Plain English: Yield spread of a bond over a risk-free curve after stripping out the value of embedded options (call, prepay). Standard relative-value metric for MBS, callable corporates. Related: Z-spread, MBS (Mortgage-Backed Security), Credit spread

OFA (Order Flow Auction)

Domain: Trading (crypto) Plain English: Mechanism in which user transactions are auctioned to searchers/solvers before public broadcast, capturing MEV for the user instead of leaking it. CoW, MEV-Share, UniswapX implementations. Related: MEV (Maximal Extractable Value), CoW Protocol, Intent-based trading

On-the-run vs off-the-run

Domain: Trading Plain English: On-the-run Treasuries are the most recently issued (and most liquid) at each maturity; off-the-run are older issues at the same nominal maturity. The yield gap reflects liquidity and repo specialness premia. Related: Treasury basis trade, Fixed income relative value (RV), Repo specials

Options (calls and puts)

Domain: Trading Plain English: Contract giving the buyer the right (not obligation) to buy (call) or sell (put) an underlying at a strike price by an expiration. American options are exercisable any time; European only at expiry. Related: Black-Scholes-Merton formula, Greeks (options Greeks), Put-call parity

Order book

Domain: Trading Plain English: Aggregated list of standing buy and sell limit orders at each price level. Level 1 = best bid/offer + last trade; Level 2 = depth across multiple price levels; Level 3 = individual orders. Related: Bid-ask spread, NBBO (National Best Bid and Offer)

Order types

Domain: Trading Plain English: Standard varieties include: market (execute at best available), limit (execute only at named price or better), stop (becomes market when trigger hit), stop-limit (becomes limit at trigger), trailing stop (stop that adjusts with favorable moves), IOC (immediate-or-cancel), FOK (fill-or-kill), GTC (good-til-cancelled), GTD (good-til-date), MOO/MOC/LOO/LOC (market/limit on open/close), iceberg (displays only part of size), hidden (entirely undisplayed). Related: Order book, Smart order router

Pairs trading

Domain: Trading Plain English: Long one asset, short a related asset, betting their historical price relationship mean-reverts. Foundational stat-arb technique. Modern variants use cointegration or machine learning to select pairs. Related: Cointegration, Stat arb (statistical arbitrage), Mean reversion

Painting the tape

Domain: Trading Plain English: Manipulative practice of trading among colluding parties to create the illusion of activity or to mark closing prices. Illegal. Related: Wash trading, Spoofing, Layering

PBS (Proposer-Builder Separation)

Domain: Trading (crypto) Plain English: Ethereum design principle separating block construction (builders) from block proposal/inclusion (validators/proposers). Reduces MEV-driven validator centralization. Implemented in practice via MEV-Boost; in-protocol PBS (ePBS) is on the roadmap. Related: MEV-Boost, Builder (Ethereum / PBS), Proposer (Ethereum)

Perpetual swap (perp)

Domain: Trading (crypto) Plain English: Derivative that mimics holding the underlying with leverage but has no expiry. Funding payments between longs and shorts anchor it to spot. Originated on BitMEX (2016); dominant trading instrument in crypto. Related: Funding rate (perp / funding-rate-crypto), dYdX, GMX / GLP, Hyperliquid

PFOF (Payment for Order Flow)

Domain: Trading Plain English: Wholesalers pay retail brokers for the right to internalize retail orders. Profits from the spread; offers price improvement vs displayed NBBO. SEC's Reg Best Ex (2024) and proposed Order Competition Rule (2022, partially withdrawn) target this market structure. Why it matters: Foundation of "zero-commission" retail trading; controversial. Related: Internalization, Regulation NMS, NBBO (National Best Bid and Offer)

Pod shop

Domain: Trading Plain English: Multi-strat hedge fund organizational model in which capital is allocated to many autonomous PM "pods" with tight risk and drawdown limits. Synonym for the structure used by Citadel, Millennium, et al. Related: Multi-strat platforms, Sleeve, Drawdown stop

Position sizing

Domain: Trading Plain English: Process of deciding how much capital or risk to allocate to a given trade. Standard rules: fixed fraction, volatility-targeted, Kelly criterion / fractional Kelly, risk-parity weights. Related: Kelly criterion, Risk budgeting, Risk parity

Premium (in trading)

Domain: Trading; Multi Plain English: Multiple distinct uses: (1) options premium = the price paid for an option; (2) bond premium = trading above par; (3) ETF premium = market price above NAV; (4) "risk premium" = expected excess return over risk-free; (5) "credit premium" = extra yield for default risk. Always specify which. Related: Equity risk premium (ERP / MRP), Term premium, Options (calls and puts)

Primary vs secondary market

Domain: Trading Plain English: Primary = where securities are first issued (IPOs, bond auctions). Secondary = where existing securities trade (NYSE, Nasdaq). Treasury auctions and corporate IPOs are primary; everything you trade in your brokerage is secondary. Related: IPO, ATM offering, Treasury auction

Put-call parity

Domain: Trading Symbol / formula: C − P = S − K·e^(−rτ) (European, no dividends) Plain English: Relationship between call, put, underlying, and discount factor that must hold to avoid arbitrage. Violations rapidly arbitraged in liquid markets. Related: Options (calls and puts), Black-Scholes-Merton formula

Quantitative easing

Domain: Trading / Macro Plain English: See QE (Quantitative Easing) in macro section.

Quote stuffing

Domain: Trading Plain English: Sending and immediately canceling a flood of orders to slow down market data feeds and gain a microstructural edge. Regulators have prosecuted some cases under spoofing/disruptive-trading rules. Related: Spoofing, Layering, HFT (High-Frequency Trading)

Range order

Domain: Trading (crypto) Plain English: Concentrated-liquidity position on Uniswap V3 (or similar) priced in a narrow range — effectively a passive limit order that executes as price moves through the range. Related: Concentrated liquidity (Uniswap V3), AMM (Automated Market Maker)

Regulation NMS

Domain: Trading (regulation) Plain English: SEC's 2005 framework restructuring U.S. equity markets. Key rules: Order Protection Rule (protect best displayed quotes), Access Rule (fair venue access), Sub-Penny Rule (no sub-penny quoting > $1), Market Data Rules. Why it matters: Defines U.S. equity market structure. Subject to ongoing rulemaking debates (tick size, round lots, NBBO data). Related: Order Protection Rule, NBBO (National Best Bid and Offer), Locked / crossed market

Repo (repurchase agreement)

Domain: Trading Plain English: Short-term collateralized loan: lender buys a security from borrower with an agreement to sell it back (at a slightly higher price) at a set date. Economically a secured loan. SOFR is the most important repo rate benchmark. Why it matters: Dominant short-term funding market; September 2019 repo spike illustrated its fragility. Related: Reverse repo, SOFR (Secured Overnight Financing Rate), SRF (Standing Repo Facility), ON RRP (Overnight Reverse Repo Facility)

Restaking (EigenLayer)

Domain: Trading (crypto) Plain English: Mechanism letting ETH stakers reuse their staked ETH (or LSTs) as economic security for additional protocols (oracles, bridges, DA layers). EigenLayer is the canonical implementation. Adds compounded slashing risk. Why it matters: Major 2023–24 narrative in crypto; reshapes security and yield landscape. Related: Restaking (EigenLayer), LST (Liquid Staking Token), LRT (Liquid Restaking Token)

Reverse repo

Domain: Trading Plain English: The other side of a Repo (repurchase agreement): lender provides cash, borrower provides collateral. From the lender's perspective. The Fed's ON RRP (Overnight Reverse Repo Facility) is operationally a reverse repo from the Fed's perspective. Related: Repo (repurchase agreement), ON RRP (Overnight Reverse Repo Facility)

Risk parity

Domain: Trading Plain English: Portfolio construction approach in which each asset (or asset class) contributes equally to total portfolio risk. Typically requires leveraging up low-vol assets (bonds) and de-weighting high-vol (equities). Bridgewater All-Weather is the flagship. Why it matters: Major institutional allocation paradigm; struggled badly in 2022 when stocks and bonds both fell. Related: All Weather, Max diversification, Equal-risk contribution

RMW / CMA

Domain: Trading (factor) Plain English: Fama-French 5-factor profitability ("Robust Minus Weak") and investment ("Conservative Minus Aggressive") factors. Capture the returns to high-profitability and low-investment firms. Make HML (High Minus Low) redundant in some specifications. Related: Fama-French, HML (High Minus Low), Hou-Xue-Zhang (q-factor model)

Roll yield

Domain: Trading Plain English: Return earned (or lost) from rolling a futures position to the next contract month, holding spot unchanged. Positive in backwardation (you sell expensive front, buy cheap next), negative in contango. Why it matters: Major driver of commodity ETF and VIX ETP returns over long horizons. Related: Contango, Backwardation, Basis (futures − spot)

Sandwich attack

Domain: Trading (crypto) Plain English: MEV strategy: when a user's swap is pending in the mempool, the searcher buys before it (pushing price up), lets the user trade at a worse price, then sells after (capturing the price impact). User loses; searcher profits. Related: MEV (Maximal Extractable Value), Searcher (MEV), Front-running

Searcher (MEV)

Domain: Trading (crypto) Plain English: An entity that scans the mempool and constructs MEV bundles (sequences of transactions) submitted to builders for inclusion. Bids in priority fees or builder payments for ordering rights. Related: MEV (Maximal Extractable Value), Builder (Ethereum / PBS), Flashbots

Securities lending

Domain: Trading Plain English: Lender lends a security (typically to a short seller, prime broker, or hedger) against cash or non-cash collateral. Earns a lending fee; harder-to-borrow names earn more. Why it matters: Backbone of Short selling; fee dynamics inform short-interest analysis. Related: Short selling, Hard-to-borrow, Locate

Sharpe ratio

Domain: Trading Symbol / formula: SR = (R_p − R_f) / σ_p Plain English: Excess return per unit of total volatility. Standard risk-adjusted return metric. Misleading when returns are heavily skewed or fat-tailed; see Sortino ratio, Deflated Sharpe ratio (Bailey-López de Prado). Related: Sortino ratio, Calmar ratio, Information ratio (IR), Deflated Sharpe ratio (Bailey-López de Prado)

Short selling

Domain: Trading Plain English: Sell a borrowed security with the intent of buying it back later at a lower price. Borrower pays a lending fee and is exposed to recall risk. Requires a Locate; naked shorts (no locate) are generally restricted. Related: Securities lending, Hard-to-borrow, Short squeeze

Short squeeze

Domain: Trading Plain English: Sharp upward price move forcing short sellers to buy in and cover, fueling further upside. Famously combined with Gamma squeeze in GME (Jan 2021). Related: Gamma squeeze, Meme stock, Short selling

Slippage

Domain: Trading Plain English: Difference between expected execution price and actual fill. Caused by latency, market impact, and adverse selection. Usually quoted in basis points. Related: Market impact, Implementation shortfall (IS)

Smart beta

Domain: Trading Plain English: Index-like products that systematically tilt toward known factors (value, momentum, quality, low-vol) instead of market-cap weighting. Often via rules-based ETFs. Marketing term as much as analytical category. Related: Factor models (Fama-French and successors), Risk parity, Fama-French

SOFR (Secured Overnight Financing Rate)

Domain: Trading / Macro Plain English: Volume-weighted median rate on overnight Treasury repo, published by the NY Fed. Replaced USD LIBOR for cleared rates from 2023. Why it matters: Now the primary USD reference rate; underlies trillions in derivatives and floating-rate debt. Related: LIBOR transition, Repo (repurchase agreement), OATs OIS (spread)

Solver

Domain: Trading (crypto) Plain English: Off-chain agent in intent-based protocols that constructs execution paths fulfilling user intents and bids to be selected. CoW, UniswapX, 1inch Fusion, Across use solver competition. Related: Intent-based trading, CoW Protocol, OFA (Order Flow Auction)

Sortino ratio

Domain: Trading Plain English: Like Sharpe ratio but uses only downside deviation in the denominator. Argues that upside vol shouldn't be penalized. Related: Sharpe ratio, Calmar ratio

SPAC (Special Purpose Acquisition Company)

Domain: Trading Plain English: A shell company that IPOs with a pile of cash, then must acquire a real operating business within ~2 years (otherwise return cash). Massive 2020–21 boom; collapsed in 2022 amid post-deal underperformance and SEC rules tightening (2024). Related: IPO, Direct listing, PIPE (Private Investment in Public Equity)

SPAN (Standard Portfolio Analysis of Risk)

Domain: Trading Plain English: CME-developed margin system that calculates worst-case loss across a portfolio under a grid of price-vol scenarios. Widely used by futures CCPs. Related: VaR (Value at Risk), CCP (Central Counterparty), Portfolio margin

Spoofing

Domain: Trading Plain English: Illegal market manipulation: place orders with no intent to execute, cancel before fill, to create false impression of supply/demand. Criminalized by Dodd-Frank §747. Notable convictions: Sarao (2015 flash crash), Coscia (2014). Related: Layering, Quote stuffing, Wash trading

Stablecoin

Domain: Trading (crypto) Plain English: Crypto asset designed to track a reference (usually USD). Three main types: (1) fiat-backed (USDC, USDT) — reserves in cash and bills; (2) crypto-collateralized (DAI) — overcollateralized with on-chain assets; (3) algorithmic (UST historically, now mostly dead). Stablecoin float exceeds $200B by mid-2025. Why it matters: Settlement medium of crypto markets; rapidly growing regulatory focus (U.S. GENIUS Act 2025, EU MiCA 2024). Related: Depeg, USDC, DAI, Tether

Stableswap (Curve)

Domain: Trading (crypto) Plain English: Curve Finance's AMM invariant designed for assets that should trade near parity (stablecoins, LSTs). Mostly constant-sum near the peg (low slippage), shifting to constant-product as imbalance grows. Related: AMM (Automated Market Maker), Constant product (AMM), Concentrated liquidity (Uniswap V3)

Stat arb (statistical arbitrage)

Domain: Trading Plain English: Family of quantitative strategies exploiting statistical patterns across many assets — pairs, cross-sectional momentum/reversal, residual returns. Typically market-neutral, short holding periods, modest per-trade edges across many positions. Related: Pairs trading, Cointegration, Equity market neutral

Stochastic vol (Heston, SABR)

Domain: Trading Plain English: Option pricing model in which volatility is itself a stochastic process. Heston (1993) has mean-reverting square-root vol; SABR (Hagan et al. 2002) is a forward-vol model widely used for swaptions. Generates realistic smiles and dynamics. Related: Black-Scholes-Merton formula, Local vol, Implied volatility (IV)

Stress testing

Domain: Trading / Multi Plain English: Estimating portfolio losses under defined hypothetical scenarios (historical, hypothetical, supervisory). Standard supervisory programs: CCAR (Comprehensive Capital Analysis and Review), DFAST (Dodd-Frank Act Stress Test), BoE/ECB stress tests. Why it matters: Core risk-management tool; supervisory anchor. Related: VaR (Value at Risk), Expected shortfall (ES / CVaR), CCAR (Comprehensive Capital Analysis and Review), NGFS scenarios

Swap (interest rate / swap-interest-rate)

Domain: Trading Plain English: OTC contract in which two parties exchange interest payments — typically fixed for floating — on a notional principal. Most cleared through CCPs since post-GFC reforms. The fixed leg defines the swap rate. Related: Swaption, OATs OIS (spread), Cap and floor (cap-floor / interest rate)

Systematic macro

Domain: Trading (practitioner archetype) Plain English: Rules-based macro fund that trades global futures (rates, FX, commodities, equities) on systematic signals — typically trend, carry, value, macro factors. Includes managed-futures CTAs (Man AHL, Aspect, Winton). Related: CTA (Commodity Trading Advisor / managed futures), Discretionary macro, Trend following

Term structure of volatility

Domain: Trading Plain English: How implied volatility varies with option maturity. Upward sloping in normal times, inverts in stress. Drives calendar spread pricing and VIX-vs-3M VIX trades. Related: Vol smile / skew, Vol skew, Implied volatility (IV)

Theta

Domain: Trading (options) Symbol / formula: θ = ∂V/∂τ (often negated to "decay per day") Plain English: Time decay of an option's value. Long options pay theta (lose value as time passes); short options collect theta. Sharpest near expiry for ATM options. Related: Greeks (options Greeks), Delta, Gamma

Tick (Uniswap V3 / tick-uniswap)

Domain: Trading (crypto) Plain English: Discrete price step (1.0001 ratio per tick) used to bucket concentrated-liquidity positions. Liquidity is tracked tick-by-tick. Related: Concentrated liquidity (Uniswap V3), AMM (Automated Market Maker)

Tracking error

Domain: Trading Symbol / formula: TE = σ(R_p − R_b) Plain English: Standard deviation of the difference between portfolio and benchmark returns. Index funds aim for very low TE; active funds run higher TE to chase alpha. Related: Active share, Information ratio (IR)

Treasury basis trade

Domain: Trading Plain English: Cash-and-carry trade in U.S. Treasuries: buy the cheapest-to-deliver bond, sell the corresponding futures, finance via repo, deliver into the future. Edge is small but levered enormously (often 50:1+) by hedge funds. Hedge-fund net short Treasury futures positions reached records in 2023–25. SEC, FSOC, Treasury, and academic researchers have raised systemic concerns since 2020. Why it matters: Linchpin of cash-futures price coherence and a recurring fragility (March 2020). Related: Cash-and-carry arbitrage, CTD (Cheapest to Deliver), Fixed income relative value (RV), Basis (futures − spot)

Trinomial tree

Domain: Trading Plain English: Discrete option pricing with three branches per node (up/flat/down). More flexible than binomial; converges faster but more complex to implement. Related: Binomial tree, Black-Scholes-Merton formula

TWAP / VWAP

Domain: Trading Plain English: Time-Weighted Average Price = average price over a period weighted by time; Volume-Weighted Average Price = weighted by volume. Execution benchmarks and algos. "Beat the VWAP" is a standard execution-quality measure. Related: IS algorithm (Implementation Shortfall), Implementation shortfall (IS), Almgren-Chriss model

TWAP oracle

Domain: Trading (crypto) Plain English: On-chain price feed computed as a time-weighted average of recent observations (often Uniswap V2 cumulative prices). Resistant to short-term manipulation but lags spot. Related: Oracle, Chainlink, MEV (Maximal Extractable Value)

Variance swap

Domain: Trading Plain English: OTC derivative paying the buyer the difference between realized variance (over a period) and a fixed strike variance, times a notional. Provides pure exposure to realized vol (squared), unlike vol swaps (linear). Related: Volatility swap, Implied volatility (IV), VIX

VaR (Value at Risk)

Domain: Trading Plain English: Loss that won't be exceeded over a specified horizon with a specified probability — e.g., 1-day 99% VaR = $10M means there's a 1% chance of losing more than $10M tomorrow. Critiqued for ignoring tail magnitude, replaced by Expected shortfall (ES / CVaR) in FRTB. Related: Expected shortfall (ES / CVaR), Stress testing, FRTB (Fundamental Review of the Trading Book)

Ve(3,3) / veToken

Domain: Trading (crypto) Plain English: Vote-escrowed token model (introduced by Curve via veCRV) where users lock governance tokens for time-weighted voting power and a share of protocol fees / emissions direction. (3,3) refers to game-theoretic incentive design from OlympusDAO. Why it matters: Underlies the "Bribe markets (MEV)" ecosystem (Convex, Aura, Votium). Related: Bribe markets (MEV), Governance token, Liquidity mining

Vega

Domain: Trading (options) Symbol / formula: ν = ∂V/∂σ Plain English: Sensitivity of option price to a 1-percentage-point change in implied volatility. Long options have positive vega; short options negative. Related: Greeks (options Greeks), Implied volatility (IV), Vanna / charm / vomma

VIX

Domain: Trading Plain English: CBOE's Volatility Index. Model-free implied volatility of 30-day SPX options, expressed in annualized percent. "Fear gauge." VIX1D is the new 1-day variant launched 2023. Related: Implied volatility (IV), Vol skew, Skew index, VVIX

Vol smile / skew

Domain: Trading Plain English: Smile = U-shaped implied-vol-vs-strike curve (high vol for very ITM and very OTM, low ATM); skew = monotonically decreasing IV from low strikes to high (typical for equity indices, reflecting crash fears). Related: Implied volatility (IV), Local vol, Stochastic vol (Heston, SABR)

Volatility (realized, implied)

Domain: Trading Plain English: Realized = sample standard deviation of past returns (often annualized: σ_daily × √252). Implied = vol level consistent with observed option prices. Realized backward-looking, implied forward-looking risk-neutral expectation. Related: Implied volatility (IV), VIX, GARCH

Volcker Rule

Domain: Trading (regulation) Plain English: Dodd-Frank §619: prohibits banks from proprietary trading and from owning/sponsoring hedge funds and PE funds, with exemptions for market making, hedging, and underwriting. Substantially loosened in 2019–2020 amendments. Why it matters: Reshaped bank trading-book activity post-GFC; arguably reduced dealer market-making capacity. Related: Dodd-Frank, Adverse selection (market making), FRTB (Fundamental Review of the Trading Book)

Walk-forward analysis

Domain: Trading Plain English: Backtest design that repeatedly trains on a moving past window and tests on the next out-of-sample window. Closer to live conditions than fixed train/test splits. Related: Backtesting, Purged k-fold CV, Combinatorial purged CV

Wash trading

Domain: Trading Plain English: Buying and selling the same asset to inflate volume or create the appearance of activity. Illegal in regulated markets; pervasive in some segments of crypto, where regulators and analysts (Bitwise 2019, BIS 2023) have flagged extreme wash trading on smaller venues. Related: Painting the tape, Layering, Spoofing

Z-spread

Domain: Trading Plain English: Constant spread added to the entire Treasury spot-rate curve such that the discounted cash flows of a bond equal its price. More accurate than G-spread for bonds with non-bullet cash flows; doesn't strip embedded options (use OAS for that). Related: OAS (Option-Adjusted Spread), Credit spread, Asset swap

zk-rollup

Domain: Trading (crypto) Plain English: L2 scaling solution that uses zero-knowledge proofs to attest that batched off-chain transactions are valid, with the proof verified by an L1 smart contract. Contrast with Optimistic rollup which relies on fraud-proof challenge windows. Examples: zkSync, StarkNet, Scroll, Linea, Polygon zkEVM. Related: Optimistic rollup, L2 (Layer 2), Rollup-centric roadmap, Blob (EIP-4844)

Multi-domain / cross-cutting terms

Basel III / IV

Domain: Multi (regulation) Plain English: Post-GFC bank capital and liquidity standards from the Basel Committee on Banking Supervision. III (2010, phased through 2019) raised capital ratios, introduced LCR and NSFR liquidity rules, and added the leverage ratio. "Basel IV" (informal; officially Basel III finalisation 2017, mostly effective from 2023–25) standardizes risk weights and adds output floors. Why it matters: Defines the regulatory architecture of global banking. Related: FRTB (Fundamental Review of the Trading Book), SLR (Supplementary Leverage Ratio), G-SIB / D-SIB (gsib / dsib), CCAR (Comprehensive Capital Analysis and Review)

Black-Scholes-Merton (cross-listing)

Domain: Multi Plain English: See Black-Scholes-Merton formula. Listed in trading section but its mathematics (geometric Brownian motion, risk-neutral measure, no-arbitrage pricing) is also macro/quant lingua franca. Related: Greeks (options Greeks), Implied volatility (IV)

Bank run

Domain: Multi Plain English: When depositors withdraw funds en masse from a bank because they fear it will fail, often making the failure self-fulfilling. Modern equivalents include runs on repo, MMFs, and crypto exchanges. SVB (March 2023) showed digital-era runs are much faster than 1930s analogs. Why it matters: Recurring source of financial fragility; motivates deposit insurance, lender-of-last-resort, and liquidity regulation. Related: Diamond-Dybvig model, SVB (Silicon Valley Bank, March 2023), Deposit insurance, Repo run

Basis point

Domain: Multi Plain English: See Basis point (bp).

Bayes' rule

Domain: Multi Symbol / formula: P(A|B) = P(B|A)·P(A)/P(B) Plain English: Updates a prior belief P(A) into a posterior P(A|B) after observing data B. Foundational for Bayesian estimation (of DSGE), Bayesian persuasion, and modern econometrics. Why it matters: Core probability identity used everywhere from DSGE estimation to portfolio choice. Related: Bayesian estimation (of DSGE), Bayesian persuasion, Bayesian Nash equilibrium

CCAR (Comprehensive Capital Analysis and Review)

Domain: Multi (regulation) Plain English: Annual Fed supervisory stress test for large U.S. banks. Evaluates whether banks have enough capital to absorb losses under severe scenarios and continue lending. Sets the stress capital buffer add-on to minimum capital ratios. Why it matters: Defines U.S. large-bank capital planning. Related: DFAST (Dodd-Frank Act Stress Test), Stress capital buffer, Basel III / IV

CDO (Collateralized Debt Obligation)

Domain: Multi Plain English: Structured product that pools cash-flowing assets (loans, bonds, other ABS) and slices them into tranches by seniority. CLOs (collateralized loan obligations) are CDOs backed by leveraged loans; revived strongly post-2010. Why it matters: Central to the GFC; current CLO market is large and credit-cycle-relevant. Related: MBS (Mortgage-Backed Security), Asset-backed security (ABS), Tranche

Convenience yield

Domain: Multi Plain English: Non-pecuniary value from holding an asset directly — for commodities, the optionality of physical inventory; for Treasuries, the "money-like" safety and collateral value (Krishnamurthy-Vissing-Jorgensen). Manifests as yield lower than the no-arbitrage value. Why it matters: Explains persistent gaps between Treasury yields and OIS/swap rates and parts of Term premium dynamics. Related: Term premium, Swap spread, Treasury basis trade

Credit Suisse 2023

Domain: Multi Plain English: Switzerland's second-largest bank, brought down March 2023 by years of scandals capped by deposit flight after SVB; absorbed in an emergency UBS-led merger orchestrated by the Swiss government, with controversial total write-down of AT1 bonds. Why it matters: Major test case for the post-GFC resolution framework and for the legal treatment of AT1 (CoCo) instruments. Related: SVB (Silicon Valley Bank, March 2023), First Republic Bank, Bank run, AT1 / CoCo (at1-coco / Additional Tier 1 / contingent convertible)

Currency crisis (first / second / third generation)

Domain: Multi Plain English: First gen (Krugman 1979): inconsistent fiscal/monetary policies exhaust reserves and force devaluation. Second gen (Obstfeld 1996): self-fulfilling panics when policy is consistent but vulnerable. Third gen (post-Asian-1997): banking, corporate, and currency crises feed each other. Why it matters: Standard taxonomy for emerging market vulnerabilities. Related: Sudden stop, Original sin, Trilemma (international finance)

DCF (Discounted Cash Flow)

Domain: Multi Symbol / formula: PV = Σ CF_t / (1+r)^t + TV / (1+r)^N Plain English: Value an asset by projecting its future cash flows and discounting them to the present at an appropriate rate. Used for stocks, projects, bonds, businesses. The whole discipline of corporate finance is largely DCF with bells. Related: WACC (Weighted Average Cost of Capital), Terminal value, NPV (Net Present Value), Discount (in finance)

Default rate

Domain: Multi Plain English: Fraction of credits (loans, bonds) that default over a period. Trailing-12-month HY default rates are headline credit-cycle metrics; Moody's and S&P publish standard series. Related: Recovery rate, EAD / PD / LGD / EL / RWA, Expected loss

Diamond-Dybvig model

Domain: Multi Plain English: 1983 model of bank runs. Banks transform illiquid long-term assets into liquid short-term deposits, providing insurance to depositors but creating two equilibria: a good (no-run) one and a bad (run) one. Deposit insurance or a lender-of-last-resort selects the good equilibrium. Why it matters: Foundational frame for thinking about bank runs and the design of deposit insurance, payment systems, and liquidity backstops. Related: Bank run, Lender of last resort (LoLR), Deposit insurance

Discount (Fed discount rate / DCF discount rate / bond at discount)

Domain: Multi Plain English: See Discount (in finance) in trading section. Three different meanings.

Distressed debt

Domain: Multi Plain English: Bonds or loans of issuers in or near default, typically trading well below par. Distressed investors buy this paper expecting outsized recoveries or to control the restructuring. Mostly L/S or activist hedge funds, "loan-to-own" PE. Related: Event-driven, Default rate, Recovery rate

Dodd-Frank

Domain: Multi (regulation) Plain English: U.S. 2010 post-GFC reform: CCAR/DFAST, Volcker Rule, Title VII derivatives clearing, FSOC, CFPB, Orderly Liquidation Authority. Partially rolled back by 2018 EGRRCPA for mid-sized banks; that rollback is widely cited as a contributor to SVB. Related: Volcker Rule, CCAR (Comprehensive Capital Analysis and Review), SVB (Silicon Valley Bank, March 2023), Basel III / IV

DTCC (Depository Trust & Clearing Corporation)

Domain: Multi Plain English: Industry-owned U.S. post-trade infrastructure — DTC (central securities depository), NSCC (equities CCP), FICC (fixed-income CCP). Handles the bulk of U.S. equity, MBS, and government-securities clearing and settlement. Related: CCP (Central Counterparty), DvP (Delivery vs Payment), T+1 (T plus 1)

EAD / PD / LGD / EL / RWA

Domain: Multi (banking) Plain English: Building blocks of bank credit-risk capital. EAD = Exposure at Default; PD = Probability of Default; LGD = Loss Given Default; EL = Expected Loss = PD × LGD × EAD; RWA = Risk-Weighted Assets, the denominator of capital ratios. Related: Basel III / IV, Default rate, Recovery rate

Equity risk premium (ERP / MRP)

Domain: Multi Plain English: Expected return on equities in excess of the risk-free rate. Realized historical excess return for the U.S. is ~5–7%; forward-looking estimates from Damodaran, Fed, AQR vary widely (2–6%). Inputs to cost of equity and asset allocation. Why it matters: Anchor parameter in valuation and portfolio choice; the Equity premium puzzle is that realized ERP is too high to be explained by standard CRRA preferences. Related: Equity premium puzzle, CAPM (Capital Asset Pricing Model), Cost of equity

Equity premium puzzle

Domain: Multi Plain English: Mehra-Prescott (1985) showed standard expected-utility consumption-based asset pricing implies an equity premium of ~0.5%, not the historical ~6%. Explanations: high effective risk aversion, rare disasters (Barro), habit formation, long-run risk, ambiguity aversion. Why it matters: Sharpest empirical challenge to representative-agent asset pricing. Related: Equity risk premium (ERP / MRP), CRRA (Constant Relative Risk Aversion), Rare disaster

FedNow

Domain: Multi Plain English: U.S. Federal Reserve's real-time gross settlement (RTGS) instant payment service for banks, live since July 2023. Transfers settle in seconds, 24/7/365. Slow uptake initially; growing through 2024–25. Related: CHIPS (Clearing House Interbank Payments System), Fedwire, RTGS (Real-Time Gross Settlement)

Fedwire

Domain: Multi Plain English: Fed's wholesale RTGS funds and securities transfer system. Settles fed funds, large-value payments, and Treasury/agency securities transfers same-day with finality. Related: CHIPS (Clearing House Interbank Payments System), FedNow, RTGS (Real-Time Gross Settlement)

Fisher equation

Domain: Multi Symbol / formula: (1 + i) = (1 + r)·(1 + π) ≈ 1 + r + π Plain English: Nominal interest rate equals real interest rate plus expected inflation. The approximate form is widely used in macro and trading. Why it matters: Connects Real interest rate to nominal rates; underlies the analysis of TIPS and inflation-linked products. Related: Real interest rate, Breakeven inflation, TIPS (Treasury Inflation-Protected Securities)

First Republic Bank

Domain: Multi Plain English: U.S. mid-sized bank seized by the FDIC in May 2023 amid post-SVB deposit flight; sold to JPMorgan. Heavy reliance on uninsured deposits and unrealized losses on long-duration loans, like SVB. Related: SVB (Silicon Valley Bank, March 2023), Bank run, Duration risk

FSOC (Financial Stability Oversight Council)

Domain: Multi (regulation) Plain English: U.S. interagency body created by Dodd-Frank to identify and respond to systemic risks. Can designate non-bank firms as systemically important (SIFI) — controversial and rarely used. Related: Dodd-Frank, G-SIB / D-SIB (gsib / dsib), Shadow banking / NBFI

G-SIB / D-SIB (gsib / dsib)

Domain: Multi (regulation) Plain English: Globally systemically important banks (designated by FSB based on size, complexity, interconnectedness) and Domestic SIBs. G-SIBs face capital surcharges (1.0–3.5%) and TLAC requirements. Related: TBTF (Too Big To Fail), Basel III / IV, TLAC (Total Loss-Absorbing Capacity)

Goodhart's Law

Domain: Multi Plain English: "When a measure becomes a target, it ceases to be a good measure." Originally stated for money-supply targets; applies broadly to OKRs, school tests, and trading signals. Why it matters: Cautionary tale for any policy or strategy keyed to a single proxy. Related: Campbell's Law

HY vs IG

Domain: Multi Plain English: High Yield (BB+ and below at S&P/Fitch, Ba1 and below at Moody's) vs Investment Grade (BBB-/Baa3 and above). The cliff matters for institutional mandates that prohibit HY exposure; "fallen angel" = downgrade from IG to HY, "rising star" = the reverse. Related: Credit spread, Fallen angel, Ratings (S&P, Moody's, Fitch)

IRR (Internal Rate of Return)

Domain: Multi Plain English: The discount rate at which NPV = 0. Standard PE/VC return metric, though sensitive to timing of cash flows and to leverage. Related: NPV (Net Present Value), DCF (Discounted Cash Flow), WACC (Weighted Average Cost of Capital)

Leverage

Domain: Multi Plain English: Multiple distinct uses across domains: (1) corporate: debt-to-equity or debt-to-assets ratio; (2) bank regulatory: total assets / tier-1 capital (SLR (Supplementary Leverage Ratio) is U.S. version); (3) hedge fund: gross or net portfolio market value / NAV; (4) derivative: notional / margin (e.g., 10x perp leverage means a 1% price move ⇒ 10% PnL on margin). Always specify. Why it matters: Same word, very different numbers and risks across contexts. Related: SLR (Supplementary Leverage Ratio), Duration (Macaulay / modified), Notional

Market microstructure

Domain: Multi Plain English: Subfield of finance studying the process by which prices are formed and trades executed — quotes, orders, dealers, exchanges, latency. Key models: Glosten-Milgrom, Kyle, Roll. Key empirics: bid-ask spreads, price impact, post-trade transparency. Related: Kyle model, Glosten-Milgrom model, Bid-ask spread, HFT (High-Frequency Trading)

Mark-to-market (MTM)

Domain: Multi Plain English: Valuing positions at current market prices, with unrealized PnL flowing through accounts each day. Standard in trading books; contested for some hold-to-maturity bank assets (SVB held duration-risky bonds in HTM at cost, masking unrealized losses). Related: Duration risk, SVB (Silicon Valley Bank, March 2023), Fair value

Money market fund reform

Domain: Multi Plain English: SEC tightened MMF rules in 2010 (after Reserve Primary breaking the buck), 2014 (floating NAV for institutional prime), and 2023 (mandatory liquidity fees for institutional prime, removed gates). Aims to make MMFs more resilient to runs. Related: Money market fund (MMF), Run on a fund, ON RRP (Overnight Reverse Repo Facility)

NPV (Net Present Value)

Domain: Multi Symbol / formula: NPV = −I_0 + Σ CF_t / (1+r)^t Plain English: Discounted cash flows minus initial investment. Standard rule: take the project if NPV > 0. Related: IRR (Internal Rate of Return), DCF (Discounted Cash Flow), WACC (Weighted Average Cost of Capital)

Original sin

Domain: Multi (international) Plain English: Eichengreen-Hausmann: emerging-market governments and firms cannot borrow long-term in their own currency from abroad. Forces them into FX mismatches that amplify crises. Related: Sudden stop, Currency crisis (first / second / third generation), Dollarization

Premium (multi-domain)

Domain: Multi Plain English: See Premium (in trading) in trading section. Equity risk premium, term premium, credit premium, liquidity premium, options premium, ETF premium-to-NAV. Always disambiguate. Related: Equity risk premium (ERP / MRP), Term premium, Credit spread

Present value

Domain: Multi Symbol / formula: PV = CF / (1+r)^t Plain English: Today's value of a cash flow due at a future date, discounted at rate r. The mathematical anchor of all finance. Related: DCF (Discounted Cash Flow), Discount (in finance), Time value of money

Ratings (S&P, Moody's, Fitch)

Domain: Multi Plain English: Credit-rating agencies assign letter ratings to bond issuers and issues. S&P/Fitch use AAA→D scale; Moody's uses Aaa→C. Investment grade cuts at BBB-/Baa3; below is High Yield. Regulated as Nationally Recognized Statistical Rating Organizations (NRSROs). Why it matters: Drive mandate eligibility, capital charges, and pricing — much more than they "should" given empirical accuracy. Related: HY vs IG, Fallen angel, Default rate

Real interest rate

Domain: Multi Symbol / formula: r ≈ i − π^e Plain English: Nominal interest rate minus expected inflation. The rate that matters for intertemporal decisions; observable for TIPS, inferred for other instruments. Related: Fisher equation, TIPS (Treasury Inflation-Protected Securities), r-star (r*)

Recovery rate

Domain: Multi Plain English: Cents on the dollar a creditor receives after default. Senior secured loans recover 60–80%, senior unsecured bonds 30–50%, subordinated 10–25%, average across the cycle. Strongly cyclical (higher recoveries in expansions). Related: EAD / PD / LGD / EL / RWA, Default rate, Distressed debt

Regulatory arbitrage

Domain: Multi Plain English: Restructuring activity to qualify for less-stringent regulation — booking trades through a thinly regulated subsidiary, redefining a product to avoid a rule, moving to a friendlier jurisdiction. Why it matters: Recurring source of macroprudential blind spots; one driver of the rise of Shadow banking / NBFI. Related: Shadow banking / NBFI, Shadow banking / NBFI, Basel III / IV

Restructuring

Domain: Multi Plain English: Renegotiation of debt terms (maturity, coupon, principal) to avoid default. Can be out-of-court or in-court (Chapter 11). "Distressed exchange" is a common variant in U.S. corporate credit; sovereign debt restructurings are governed by collective action clauses. Related: Distressed debt, Default rate, Recovery rate

Risk premium (general)

Domain: Multi Plain English: Expected excess return on a risky asset over a risk-free benchmark. Equity, term, credit, liquidity premia are the main flavors. Always defined relative to a model (CAPM, multi-factor, term structure). Related: Equity risk premium (ERP / MRP), Term premium, Credit spread

Shadow banking / NBFI

Domain: Multi Plain English: Credit intermediation outside the regulated banking system — MMFs, hedge funds, BDCs, private credit funds, MBS/ABS issuers, repo and securities-lending markets. FSB rebranded as Non-Bank Financial Intermediation (NBFI). Now > 50% of global financial assets. Why it matters: Locus of much post-GFC growth and recurring fragilities (March 2020 dash for cash, 2022 UK LDI, 2023 banking turmoil). Related: Money market fund (MMF), Shadow banking / NBFI, MBS (Mortgage-Backed Security), Regulatory arbitrage

SLR (Supplementary Leverage Ratio)

Domain: Multi (regulation) Plain English: U.S. implementation of Basel III leverage ratio: tier-1 capital / total leverage exposure (assets + off-balance sheet). Treats all assets at 100% weight, ignoring risk. Subject to ongoing debate about Treasury market liquidity (banks complaining the SLR penalizes holding Treasuries). Related: Basel III / IV, G-SIB / D-SIB (gsib / dsib), Treasury basis trade

Spread (financial)

Domain: Multi Plain English: Generic term for the gap between two prices or rates. Bid-ask spread, credit spread, swap spread, basis spread, calendar spread. Always specify. Related: Bid-ask spread, Credit spread, Swap spread

Stress capital buffer

Domain: Multi (regulation) Plain English: Bank-specific capital add-on (above 4.5% CET1 minimum) set annually by the Fed based on CCAR results. Replaced the static CCB component of capital requirements in 2020. Related: CCAR (Comprehensive Capital Analysis and Review), Basel III / IV, G-SIB / D-SIB (gsib / dsib)

SVB (Silicon Valley Bank, March 2023)

Domain: Multi Plain English: U.S. tech-focused bank that failed March 10, 2023 after $42B of deposit outflows in a single day. Held large unrealized losses on long-duration HTM Treasuries/MBS; depositors were >90% uninsured. FDIC invoked systemic-risk exception to backstop all deposits. Widely cited as the canonical case of unmanaged Duration risk. Why it matters: Defined regional-bank risk in 2023–25 and reshaped supervisory focus on AOCI, deposit concentration, and rate risk. Related: Duration risk, First Republic Bank, Credit Suisse 2023, Bank run

Swap spread

Domain: Multi Plain English: Difference between a swap rate and the same-maturity Treasury yield. Negative swap spreads (since 2015 in long maturities) reflect dealer balance-sheet costs, repo specials, and convenience yield on Treasuries. Object of relative-value trades. Related: Swap (interest rate / swap-interest-rate), Treasury basis trade, Convenience yield

T+1 (T plus 1)

Domain: Multi Plain English: U.S. equity, ETF, and corporate-bond settlement moved from T+2 to T+1 on May 28, 2024 (Canada and Mexico aligned). Trades settle one business day after execution. Why it matters: Reduces counterparty risk and margin requirements; created FX-settlement misalignment problems for global investors. Related: T+2 (T plus 2), DvP (Delivery vs Payment), CCP (Central Counterparty)

TBTF (Too Big To Fail)

Domain: Multi Plain English: The empirical fact that some institutions are large/interconnected enough that governments cannot let them fail without systemic damage. Generates implicit subsidies and moral hazard. Post-GFC reforms (G-SIB surcharges, TLAC, resolution planning) aim to make failure feasible. Related: G-SIB / D-SIB (gsib / dsib), Moral hazard, Resolution planning

Term premium (cross-listed)

Domain: Multi Plain English: See Term premium.

Time value of money

Domain: Multi Plain English: A dollar today is worth more than a dollar tomorrow because today's dollar can be invested. Foundation for DCF (Discounted Cash Flow), NPV (Net Present Value), and bond pricing. Related: Present value, Discount (in finance), DCF (Discounted Cash Flow)

TLAC (Total Loss-Absorbing Capacity)

Domain: Multi (regulation) Plain English: FSB standard requiring G-SIBs to hold a layer of bail-in-able debt and capital sufficient to absorb losses and recapitalize the firm in resolution. Typically 16–18% of RWA + 6% of leverage exposure. Related: G-SIB / D-SIB (gsib / dsib), Basel III / IV, TBTF (Too Big To Fail)

Tranching

Domain: Multi Plain English: Slicing a pool of cash flows into seniority classes (equity, mezzanine, senior). Senior tranches get paid first; equity absorbs first losses. Concentrates risk and creates rated AAA paper from BBB underlying. Related: CDO (Collateralized Debt Obligation), MBS (Mortgage-Backed Security), Asset-backed security (ABS)

WACC (Weighted Average Cost of Capital)

Domain: Multi Symbol / formula: WACC = (E/V)·r_e + (D/V)·r_d·(1−T) Plain English: Discount rate combining cost of equity and after-tax cost of debt, weighted by their shares in total enterprise value. Standard DCF discount rate for corporate-level projects. Related: DCF (Discounted Cash Flow), NPV (Net Present Value), Cost of equity, CAPM (Capital Asset Pricing Model)

Yield (curve, spread, etc.)

Domain: Multi Plain English: Yield = return earned by holding a bond, typically expressed as an annualized rate. Yield curve = yields plotted against maturity. Yield spread = difference between two yields. Forward yield = yield on a forward-starting period derived from the curve. Related: Bond, Yield curve, Credit spread

Yield curve

Domain: Multi Plain English: Curve of yields against maturities for bonds of the same credit quality (most often Treasuries). Normally upward-sloping; inversions (2y > 10y, 3m > 10y) have preceded most U.S. recessions, including 2022–23. The U.S. yield curve fully un-inverted in late 2024. Why it matters: Most-watched leading indicator and the input to Term premium decomposition. Related: Term premium, Expectations hypothesis (term structure), Recession dating (NBER BCDC)

Greek letters & special symbols

Quick reference. See individual entries for full definitions.

Common confusions / collisions to be careful about:

• β: CAPM beta vs DSGE discount factor — usually clear from context but both will appear in any cross-domain DSGE-asset-pricing model (Bansal-Yaron).
• π: Inflation in macro, profit in micro. In a HANK paper you'll see both within paragraphs of each other.
• δ: Depreciation in macro vs hyperbolic-discount present-bias in behavioral micro vs delta in trading.
• σ: Standard deviation in stats, volatility in trading, elasticity of intertemporal substitution in macro (often denoted 1/σ or ψ).
• τ: Tax rate in fiscal economics, time-to-maturity in options.
• r: Real or nominal interest rate (macro), return (trading), regression "correlation r."
• Σ: Summation operator vs covariance matrix.

Source inventory

Definitions in this glossary were verified against the following authoritative sources, with formal/academic forms preferred where popular usage diverges.

General / cross-domain

• IMF Glossary of Selected Financial Terms; IMF World Economic Outlook glossaries.
• OECD Glossary of Statistical Terms.
• BIS glossary (esp. monetary statistics and CPMI definitions).
• FSB key terms (e.g., G-SIB, TLAC, NBFI).
• Investopedia (used as a starting point; technical claims cross-checked against textbooks).

Microeconomics

• Mas-Colell, Whinston, Green, Microeconomic Theory (1995).
• Mankiw, Principles of Microeconomics (latest editions).
• Tirole, The Theory of Industrial Organization (1988).
• Roth, Who Gets What — and Why (2015) for market design.
• Berry-Levinsohn-Pakes (1995) for BLP.
• Kahneman-Tversky (1979) and Kahneman, Thinking Fast and Slow (2011) for behavioral.
• Chetty (2009) "Sufficient Statistics for Welfare Analysis."
• Kamenica-Gentzkow (2011) for Bayesian persuasion.

Macroeconomics

• Federal Reserve education materials (federalreserve.gov, FRED documentation).
• Federal Reserve Bank of Atlanta (GDPNow, sticky-price CPI, wage tracker).
• Federal Reserve Bank of Cleveland (median/trimmed-mean CPI).
• Federal Reserve Bank of Dallas (trimmed-mean PCE).
• BLS Handbook of Methods (CPI, ECI, JOLTS, CES).
• BEA NIPA handbook (GDP, GDI, PCE).
• ECB educational materials and Economic Bulletin.
• BIS Annual Economic Reports.
• NGFS scenario documentation.
• Mankiw, Macroeconomics; Romer, Advanced Macroeconomics; Galí, Monetary Policy, Inflation, and the Business Cycle; Acemoglu, Introduction to Modern Economic Growth.
• Kaplan-Moll-Violante (2018) for HANK; Auclert-Rognlie-Straub for iMPC; Holston-Laubach-Williams for r*; Sahm (2019) for Sahm rule.
• Fed framework documents: 2020 Statement on Longer-Run Goals (FAIT); 2025 framework review statements.

Market trading

• Hull, Options, Futures, and Other Derivatives (10th–11th ed.).
• Bodie, Kane, Marcus, Investments.
• Fabozzi, Handbook of Fixed Income Securities.
• Pedersen, Efficiently Inefficient (2015).
• López de Prado, Advances in Financial Machine Learning (2018) and Machine Learning for Asset Managers (2020).
• Fama-French papers (1992, 1993, 2015) for factors; Carhart (1997); Hou-Xue-Zhang (2015) for q-factor.
• Cochrane, Asset Pricing.
• O'Hara, Market Microstructure Theory (1995); Hasbrouck, Empirical Market Microstructure (2007).
• Almgren-Chriss (2001) for execution.
• SEC and FINRA rulemaking / market structure papers (Reg NMS, Reg ATS, MiFID II background, FRTB).
• CBOE methodology documents (VIX, VVIX, VIX1D, SKEW).
• Treasury OFR, Fed staff working papers on Treasury basis trade (2023–2025 vintage).

Crypto / DeFi

• Uniswap V2 and V3 whitepapers.
• Curve and Balancer documentation.
• Flashbots research and MEV-Boost documentation.
• Ethereum.org docs (EIP-1559, EIP-4844, PBS roadmap).
• a16z crypto and Paradigm research glossaries and posts.
• Chainalysis Crypto Crime Reports (used skeptically for prevalence data).
• DefiLlama for TVL/protocol scale numbers (verified late; figures change daily).
• Industry primers: dYdX docs, GMX docs, EigenLayer whitepaper.

Regulation / banking

• BCBS standards (Basel III/IV, FRTB).
• Federal Reserve Supervision and Regulation Letters, CCAR/DFAST instructions and results.
• ESMA and ECB documents (MiFID II/MiFIR review, EMIR REFIT).
• FSB documents on NBFI, TLAC, G-SIB.
• Fed and FDIC post-mortems on SVB, Signature, First Republic (April 2023 reviews).

Notes on contested terms Where definitions or estimates are contested or evolving — e.g., SCC, r*, equity risk premium, MEV magnitudes, fiscal multipliers, NAIRU, real-time potential output — the entry surfaces the dispute rather than pretending to settle it. Always check the latest official source for freshness-sensitive figures (CPI methodology, OAS rules, Basel transitional periods, stablecoin reserve disclosures).

Additional terms (supplementary, organized by domain)

The following entries supplement the main alphabetical sections above. They cover important terms from the brief's checklist that warrant separate definitions but were folded into other entries in the body for space. Cross-reference normally.

Microeconomics supplementary

EITC (Earned Income Tax Credit)

Domain: Micro (public) Plain English: Refundable U.S. tax credit for low- and moderate-income working households, phased in with earnings and phased out at higher incomes. Largest U.S. anti-poverty program for working families. Why it matters: Empirically large work-incentive and poverty effects; canonical case in optimal-tax literature. Related: Optimal taxation (Mirrlees), CTC (Child Tax Credit), Minimum wage

Engel's Law

Domain: Micro Plain English: As income rises, the share spent on food falls. Hence food expenditure share is a proxy for poverty across households and time. Related: Engel curve, Normal good, Inferior good

Equal-revenue tax

Domain: Micro Plain English: Tax change designed to leave total government revenue unchanged, so the welfare comparison is across allocations not budget levels. Standard device in public-finance analysis. Related: Optimal taxation (Ramsey), Deadweight loss

General equilibrium

Domain: Micro Plain English: Walrasian framework in which all markets clear simultaneously — prices and quantities determined jointly across all goods. Arrow-Debreu existence proof is the foundational result. Contrast with partial equilibrium, which holds other markets fixed. Why it matters: Conceptual backbone of Welfare theorems (first and second); computable GE models used in trade and tax policy. Related: Welfare theorems (first and second), Arrow-Debreu, CGE model (Computable General Equilibrium)

Hicksian (compensated) demand

Domain: Micro Plain English: Demand as a function of prices and utility (held fixed) — i.e., after compensating for income effects. The cost-minimizing input bundle for a given utility. Building block of the Slutsky equation decomposition. Related: Marshallian demand, Slutsky equation, Substitution effect

Hotelling rule

Domain: Micro (natural resources) Plain English: For a non-renewable resource extracted competitively, the price net of marginal extraction cost should rise at the rate of interest. Implied by intertemporal arbitrage by resource owners. Related: Opportunity cost, Real interest rate

Intergenerational elasticity of income

Domain: Micro (inequality) Plain English: Regression coefficient of (log) child income on (log) parent income. ~0.5 in the U.S. (high persistence), ~0.2 in Denmark/Sweden (low persistence). Reverse of the "Great Gatsby curve" — countries with high inequality have lower intergenerational mobility. Related: Gini coefficient, Great Gatsby curve

Marshallian demand

Domain: Micro Plain English: Demand as a function of prices and income — the "ordinary" demand curve you see on textbook graphs. Contrast with Hicksian (compensated) demand. Related: Hicksian (compensated) demand, Slutsky equation

Palma ratio

Domain: Micro (inequality) Plain English: Income share of the top 10% divided by the share of the bottom 40%. Argued by Palma to capture inequality dynamics better than the Gini, which is dominated by middle-distribution movements. Related: Gini coefficient, Top share (income / wealth)

Pigou-Dalton transfer principle

Domain: Micro (inequality) Plain English: A small transfer from a richer to a poorer person (preserving their order) reduces inequality. Standard axiom for inequality measures; Gini and Palma both satisfy it. Related: Gini coefficient, Lorenz curve

Producer theory

Domain: Micro Plain English: Branch of microeconomics analyzing firms: cost minimization, profit maximization, supply curves, returns to scale. Cleanly dualizes consumer theory. Related: Production function, Marginal cost (MC), Isoquant

Quasi-linear utility

Domain: Micro Plain English: Utility additively separable in money and the other good(s) — U(x, m) = v(x) + m. Useful because there are no income effects on the non-money good, so consumer surplus and willingness-to-pay coincide. Related: Consumer surplus, Utility

Returns to schooling

Domain: Micro (labor) Plain English: Causal effect of an additional year of schooling on earnings. Most credible estimates (instrumented by compulsory-school laws, quarter-of-birth, etc.) cluster around 8–12% per year. Related: Human capital, Signaling (Spence), Instrumental variable (IV)

Stable matching

Domain: Micro (market design) Plain English: A matching is stable if no unmatched pair would both prefer each other to their current partners. Gale-Shapley showed at least one stable matching always exists. Related: Deferred acceptance (Gale-Shapley), Top trading cycles (TTC), Mechanism design

Strategy-proof

Domain: Micro (mechanism design) Plain English: A mechanism is strategy-proof (dominant-strategy incentive-compatible) if truthful reporting is a dominant strategy for every agent regardless of others' reports. Strong robustness property. Related: Mechanism design, Revelation principle, VCG mechanism (Vickrey-Clarke-Groves)

Top share (income / wealth)

Domain: Micro (inequality) Plain English: Share of total income or wealth held by the top 1%, 0.1%, etc. Popularized by Piketty, Saez, Zucman's WID.world. Less sensitive to bottom-distribution movements than Gini; better captures top-end dynamics. Related: Gini coefficient, Palma ratio

Transaction costs

Domain: Micro Plain English: Costs of negotiating, monitoring, and enforcing contracts; broader than financial transaction costs. Williamson and Coase made these central to the theory of the firm and to organizational economics. Related: Coase theorem, Contract theory

Macroeconomics supplementary

Anchored expectations

Domain: Macro Plain English: Long-run inflation expectations stay near target despite shorter-run inflation moves. Survey measures (Michigan, NY Fed SCE 3y, BoP/SPF) and market measures (5y5y breakeven) are watched. Anchoring is the workhorse explanation for the post-2008 "flat Phillips curve." Related: Phillips curve, Deanchoring (of inflation expectations), Breakeven inflation

Animal spirits

Domain: Macro Plain English: Keynes's term for the non-rational, sentiment-driven component of investment decisions. Modern echoes: confidence indices, uncertainty shocks (Bloom), narrative economics (Shiller). Related: Uncertainty shock, Behavioral economics

AS-AD model

Domain: Macro (pedagogical) Plain English: Textbook model with downward-sloping aggregate demand and upward-sloping short-run aggregate supply (vertical long-run AS at potential). Plots output and price level. Useful for intuition; supplanted in research by NK three-equation models. Related: IS-LM model, New Keynesian model, Output gap

Bayesian estimation (of DSGE)

Domain: Macro (econometrics) Plain English: Combine prior distributions over parameters with the likelihood from data to produce posterior distributions. Standard estimation method for modern DSGE models because it disciplines weakly-identified parameters. Related: DSGE (Dynamic Stochastic General Equilibrium) model, Calibration vs estimation, Impulse response function (IRF)

Calibration vs estimation

Domain: Macro Plain English: Calibration sets model parameters to match selected moments of the data or external estimates; estimation maximizes a likelihood or minimizes a distance criterion using full data. Most modern DSGE work uses a mix (Bayesian estimation with tight priors on certain parameters = essentially calibration). Related: DSGE (Dynamic Stochastic General Equilibrium) model, Bayesian estimation (of DSGE)

Cantillon effect

Domain: Macro (heterodox) Plain English: Cantillon's observation that new money entering the economy first benefits those who receive it earliest (close to the issuer), distorting prices and reallocating wealth. Frequently invoked by crypto and Austrian critics of QE. Related: QE (Quantitative Easing), MMT (Modern Monetary Theory), Distributional effects of monetary policy

Capital account / financial account

Domain: Macro (international) Plain English: BoP components for capital transfers (small) and financial-asset flows (large — FDI, portfolio investment, other investment, reserve assets). Mirror image of the Current account. Related: Balance of payments (BoP), Current account

Deep parameters

Domain: Macro Plain English: Structural parameters describing preferences and technology, which (per Lucas's critique) should be invariant to policy changes — in contrast to reduced-form correlations that shift with the policy regime. Related: Lucas critique, DSGE (Dynamic Stochastic General Equilibrium) model, Calibration vs estimation

Demand shock

Domain: Macro Plain English: Shift in aggregate demand from monetary, fiscal, sentiment, or external-demand sources. Moves output and inflation in the same direction in the short run. Contrast with Supply shock. Related: Supply shock, Fiscal multiplier

Green QE

Domain: Macro Plain English: Proposal that central-bank asset purchases tilt toward green bonds or away from carbon-intensive issuers, to lower the cost of capital for green investment. Resisted by central banks worried about market-neutrality and mandate creep; modest steps by ECB ("tilting" of corporate bond portfolio). Related: QE (Quantitative Easing), NGFS scenarios, Climate transition risk

Inflation swap

Domain: Macro / Trading Plain English: OTC derivative where one party pays fixed and the other pays realized inflation (CPI) over a period. Zero-coupon inflation swaps are the most liquid; their rates are an alternative measure of expected inflation alongside Breakeven inflation. Related: Breakeven inflation, TIPS (Treasury Inflation-Protected Securities)

IORB-EFFR spread

Domain: Macro Plain English: Spread between IORB and the effective fed funds rate. EFFR < IORB by design in the floor system because some non-IORB-eligible lenders (FHLBs) lend below IORB. Tracking the spread is one diagnostic for reserve scarcity. Related: IORB (Interest on Reserve Balances), Effective Federal Funds Rate (EFFR), Ample reserves regime

Lucas critique

Domain: Macro Plain English: Lucas (1976): econometric models estimated on historical data fail when used to evaluate policy changes, because reduced-form parameters shift when the policy regime shifts. Motivated the move to microfounded, deep-parameter models. Why it matters: Intellectual foundation of modern DSGE; relevant whenever someone uses a historical correlation to predict effects of a new policy. Related: Deep parameters, DSGE (Dynamic Stochastic General Equilibrium) model, Time inconsistency

Menu cost

Domain: Macro Plain English: Fixed cost of changing a price (literally reprinting menus). Microfoundation for Sticky prices alternative to Calvo. Generates state-dependent rather than time-dependent pricing. Related: Calvo pricing, Sticky prices, Rational inattention

Monetary base

Domain: Macro Plain English: Currency in circulation plus bank reserves at the central bank. Direct liability of the central bank. Exploded post-2008 with QE but doesn't mechanically determine broader monetary aggregates. Related: M1 / M2, QE (Quantitative Easing), Ample reserves regime

Natural rate of interest

Domain: Macro Plain English: See r-star (r*).

Quits rate

Domain: Macro (labor) Plain English: Voluntary separations as a share of employment, from JOLTS. Rose to 3.0% in late 2021 ("Great Resignation"); fell back to ~2.0% by 2024. Strongly correlated with subsequent wage growth. Related: JOLTS (Job Openings and Labor Turnover Survey), Atlanta Fed wage tracker

Savings-investment identity

Domain: Macro Symbol / formula: S = I + (CA) Plain English: National saving equals domestic investment plus the current account. Open-economy version of the closed-economy S = I identity. Drives much of international macro. Related: Current account, Balance of payments (BoP)

Second-round effects

Domain: Macro Plain English: Inflation feedback from initial price shocks into wages, then back into prices. Watched closely by central banks; ECB's 2022–24 communication centered on whether wage growth was generating second-round effects. Related: Wage-price spiral, Anchored expectations

Sticky information

Domain: Macro Plain English: Mankiw-Reis model where prices update continuously but information updates infrequently. Generates different inflation dynamics than Calvo, with more persistence. Related: Sticky prices, Calvo pricing, Rational inattention

Sudden stop

Domain: Macro (EM) Plain English: Abrupt reversal of capital inflows to an emerging market, forcing sharp current-account adjustment and often a currency crisis. Calvo's term; canonical EM crisis pattern. Related: Currency crisis (first / second / third generation), Original sin, Trilemma (international finance)

Trading supplementary

Carry trade (FX)

Domain: Trading Plain English: Borrow a low-yielding currency, invest in a high-yielding one. Profits if exchange rates don't move enough to offset the yield differential. Periodically blows up in violent unwinds (1998 yen, 2008, August 2024 yen). Related: Carry, Interest rate parity

CCP (Central Counterparty)

Domain: Trading Plain English: Clearing entity that interposes itself between buyer and seller, becoming buyer to every seller and seller to every buyer. Mutualizes counterparty risk via Initial margin and a default fund. CME, LCH, ICE Clear, OCC are major examples. Post-Dodd-Frank, most standardized OTC derivatives must clear through CCPs. Related: Initial margin, Variation margin, Novation

CTA (Commodity Trading Advisor / managed futures)

Domain: Trading Plain English: Registered manager that trades futures and forwards on behalf of clients. In practice, "CTA" usually refers to systematic trend-following funds (AHL, Aspect, Winton, AlphaSimplex). Long-vol profile; diversifying in bear markets. Related: Systematic macro, Trend following, CTA (Commodity Trading Advisor / managed futures)

Depeg

Domain: Trading (crypto) Plain English: A stablecoin trading away from its peg. Notable cases: UST (May 2022, terminal); USDC briefly to ~$0.87 (March 2023, during SVB exposure scare). Related: Stablecoin, USDC, DAI

Distressed (hedge fund strategy)

Domain: Trading Plain English: See Distressed debt in multi section.

Equity premium (overlap)

Domain: Trading Plain English: See Equity risk premium (ERP / MRP).

Front-running (broker)

Domain: Trading Plain English: See Front-running.

Funding liquidity

Domain: Trading Plain English: Ease of obtaining short-term funding for positions. Distinct from market liquidity. Brunnermeier-Pedersen modeled how the two can reinforce each other in spirals during crises. Related: Liquidity (market liquidity), Repo (repurchase agreement), Stress testing

GME-style dynamics

Domain: Trading Plain English: Coordinated retail buying + heavy short interest + concentrated OTM call positioning + dealer gamma hedging producing explosive upside. January 2021 GameStop was the textbook case; recurred in modified form for AMC, BBBY, and parts of 2024. Related: Gamma squeeze, Short squeeze, Meme stock

Inverse / leveraged ETP

Domain: Trading Plain English: ETF/ETN that targets a positive multiple (2x, 3x) or inverse (−1x, −2x, −3x) of an underlying's daily return. Daily reset path-dependence causes substantial decay over multi-day horizons in volatile markets. Related: Creation / redemption (ETF), Volatility drag

Locked / crossed market

Domain: Trading Plain English: Locked = bid = ask on a protected quote; crossed = bid > ask. Reg NMS prohibits both for protected quotes. Rare and brief in normal conditions; flag for venue or feed issues. Related: Regulation NMS, Order Protection Rule, NBBO (National Best Bid and Offer)

Mertonian portfolio choice

Domain: Trading Plain English: Merton (1969) intertemporal portfolio choice: with CRRA utility, the optimal share in risky assets is (μ − r) / (γ·σ²) — proportional to risk premium, inversely to variance and risk aversion. Foundation for ICAPM and modern strategic asset allocation. Related: CAPM (Capital Asset Pricing Model), Kelly criterion, ICAPM (Intertemporal CAPM)

Microwave links

Domain: Trading Plain English: Line-of-sight microwave towers used to transmit market data between exchange data centers (Chicago↔NY especially). Faster than fiber for the same route. Used by HFT firms for latency arbitrage. Related: Colocation, HFT (High-Frequency Trading), Latency arbitrage

Mutual fund

Domain: Trading Plain English: Pooled investment vehicle that issues new shares at NAV upon investor request and redeems shares at NAV. Trades once daily at the post-close NAV. Largest by AUM but losing share to ETFs. Related: Creation / redemption (ETF), Closed-end fund (CEF), NAV (Net Asset Value)

Open interest

Domain: Trading Plain English: Total number of outstanding (uncleared) derivative contracts at a point in time. Reported daily for listed futures and options. Distinct from trading volume. Related: Future (futures contract), Options (calls and puts)

Portfolio margin

Domain: Trading Plain English: U.S. margin regime (NYSE Rule 431, FINRA 4210) that calculates requirements on a portfolio basis (offsetting positions reduce requirement) rather than position-by-position. Available for qualified accounts; SPAN-based for futures. Related: SPAN (Standard Portfolio Analysis of Risk), Initial margin

Prime brokerage

Domain: Trading Plain English: Suite of services investment banks offer hedge funds — securities lending, financing, custody, capital introduction, technology. Major revenue line at GS, MS, JPM. Funding terms and haircuts vary with relationship and risk. Related: Short selling, Securities lending, Repo (repurchase agreement)

Private value (auction)

Domain: Trading Plain English: See Private value (auction) in micro section.

Proposer (Ethereum)

Domain: Trading (crypto) Plain English: The validator selected to propose a block in a given slot. Under MEV-Boost, the proposer typically picks the highest-bid block from outsourced builders. Related: Builder (Ethereum / PBS), Builder (Ethereum / PBS), MEV-Boost

Public mempool

Domain: Trading (crypto) Plain English: Set of pending transactions broadcast openly on the network, visible to anyone. Exposes transactions to MEV (Maximal Extractable Value) (front-running, sandwich attacks). Private mempools and OFA aim to reduce this exposure. Related: MEV (Maximal Extractable Value), Sandwich attack, OFA (Order Flow Auction)

Risk officer (hedge fund)

Domain: Trading Plain English: Person(s) responsible for monitoring and enforcing risk limits across the firm or a PM pod. At pod shops, often has authority to force unwinds when drawdown stops trigger. Related: Pod shop, Drawdown stop, Multi-strat platforms

Rollup-centric roadmap

Domain: Trading (crypto) Plain English: Ethereum's strategic plan (Buterin, 2020) to scale primarily by hosting execution on L2 rollups while L1 focuses on data availability and consensus. EIP-4844 (blobs) was a major milestone. Related: L2 (Layer 2), Optimistic rollup, zk-rollup, Blob (EIP-4844)

SDP (Single Dealer Platform)

Domain: Trading Plain English: Proprietary electronic trading platform run by a bank for its own clients, especially in FX and fixed income. Bank quotes from internal axe and inventory rather than connecting to a multi-dealer venue. Related: RFQ (Request for Quote), ATS (Alternative Trading System), Internalization

Time-series momentum

Domain: Trading Plain English: Strategy that buys assets that have recently gone up and sells those that have gone down — based on each asset's own past return, separately. Robust across asset classes per Moskowitz-Ooi-Pedersen 2012. Engine of CTA returns. Related: Cross-sectional momentum, Trend following, CTA (Commodity Trading Advisor / managed futures)

Triple-barrier method

Domain: Trading (ML) Plain English: López de Prado's labeling scheme for ML on financial data: each observation is labeled by which of three barriers it hits first — profit-take (upper), stop-loss (lower), or time horizon (vertical). Produces more meaningful supervised-learning targets than fixed-horizon returns. Related: Meta-labeling, Combinatorial purged CV, Lopez de Prado

Vanna / charm / vomma

Domain: Trading (options) Plain English: Second-order Greeks. Vanna = ∂Δ/∂σ (cross-sensitivity of delta to vol); Charm = ∂Δ/∂τ (delta decay over time); Vomma = ∂vega/∂σ (vega convexity). Important for dealer hedging and "vanna-charm flows" narratives in equity index dynamics. Related: Greeks (options Greeks), Delta, Gamma, Vega

Volatility risk premium (VRP)

Domain: Trading Plain English: Persistent gap by which implied volatility exceeds subsequently realized volatility. Sellers of options/variance swaps capture VRP, taking on tail risk. Underlies the long-run profitability of short-vol strategies (and their occasional violent unwinds — Feb 2018 XIV). Related: Variance swap, Implied volatility (IV), Short vol

Multi-domain supplementary

Capacity (of a strategy)

Domain: Multi Plain English: AUM beyond which a strategy's alpha decays significantly because trades move prices against the manager. Hard to estimate ex ante; the binding constraint at large quant shops. Related: Alpha decay, Market impact

CHIPS (Clearing House Interbank Payments System)

Domain: Multi Plain English: Private USD large-value payment system (operated by The Clearing House), settling on a netted basis with Fedwire-final settlement at end of day. Handles much of the international USD wholesale payment flow. Related: Fedwire, FedNow, RTGS (Real-Time Gross Settlement)

CME Group

Domain: Multi Plain English: Largest derivatives exchange operator, listing futures and options on rates, equity indices, FX, commodities, and (since 2017) bitcoin. Owns CBOT, NYMEX, COMEX. Operates SPAN (Standard Portfolio Analysis of Risk) margin and a CCP. Related: CCP (Central Counterparty), Future (futures contract), SPAN (Standard Portfolio Analysis of Risk)

Internalization

Domain: Multi Plain English: Broker matching a client order against its own inventory or against another client order rather than routing to an exchange. Common in retail equity (wholesalers like Citadel Securities, Virtu), wholesale FX, and dark pools. Related: PFOF (Payment for Order Flow), Dark pool, Best execution

Sufficient liquidity buffer

Domain: Multi Plain English: Bank or fund's stock of high-quality, easily-tradable assets adequate to meet potential outflows. Codified in LCR for banks; less standardized for non-banks but a focus of post-2020 NBFI reform debates. Related: LCR (Liquidity Coverage Ratio), Shadow banking / NBFI, Stress testing

Additional terms — second batch (organized by domain)

The entries below complete the cross-reference graph: every [[slug]] referenced in other entries that did not yet resolve gets a target here. Entries are alphabetical within each subsection.

Microeconomics — second batch

Antitrust

Domain: Micro Plain English: Body of competition law and enforcement aimed at preventing monopolization, anticompetitive mergers, cartels, and abusive conduct by dominant firms. In the U.S., Sherman Act §1 (collusion) and §2 (monopolization), Clayton Act, and FTC Act; in the EU, Articles 101–102 TFEU. Recent flagships: Google search monopolization (Judge Mehta, August 2024) and the Amazon FTC case. Why it matters: Determines whether dominant platforms can be broken up, behaviorally regulated, or left alone. Related: Market power, Natural monopoly, Collusion, Merger policy See also: covered in 03-microeconomics-sota.md §D.3 Big Tech antitrust.

Arrow-Debreu

Domain: Micro Plain English: 1954 general-equilibrium framework (Arrow, Debreu) proving existence of a competitive equilibrium under convexity, completeness of markets, and standard preferences. Each "Arrow-Debreu security" pays $1 in exactly one future state and zero elsewhere — the conceptual building blocks of state-contingent pricing. Why it matters: The mathematical backbone of General equilibrium, Welfare theorems (first and second), and Risk-neutral pricing. Related: General equilibrium, Welfare theorems (first and second), Complete markets, Risk-neutral pricing See also: covered in 03-microeconomics-sota.md §General equilibrium.

Axioms of choice

Domain: Micro (decision theory) Plain English: Set of properties — completeness, transitivity, continuity, independence — that a preference ordering must satisfy to be representable by a utility function. Independence is the contested one: violations generate the Allais and Ellsberg paradoxes and motivate non-expected-utility theory. Why it matters: Foundation of consumer theory and Expected utility; failures motivate behavioral models. Related: Expected utility, Prospect theory, Allais paradox, Utility

Backward induction

Domain: Micro (game theory) Plain English: Solving a sequential game by working from the last move forward — at each stage, players assume rational play in all subsequent subgames. Yields Subgame perfection in finite games of perfect information. Why it matters: The standard algorithm for finding credible strategies in extensive-form games. Related: Subgame perfection, Nash equilibrium, Extensive-form game

Batch auction

Domain: Micro (market design) Plain English: Auction format in which orders accumulated over an interval are cleared simultaneously at a single price. Used in opening/closing exchange auctions and proposed by Budish-Cramton-Shim as a defense against latency arbitrage in continuous markets. Why it matters: Mitigates HFT (High-Frequency Trading)-style speed races and is widely used in real-world equity opens/closes. Related: Continuous auction, Latency arbitrage, Order book See also: covered in 05-trading-theory-and-practice.md §Market microstructure.

Bertrand competition

Domain: Micro Plain English: Oligopoly model in which firms set prices simultaneously and consumers buy from the lowest-price firm. With homogeneous products and constant marginal cost, two firms is enough to drive price to MC — the "Bertrand paradox." Resolved in practice by capacity constraints, differentiation, or repeated play. Why it matters: Benchmark for price competition; counterpoint to Cournot competition (quantity setting). Related: Cournot competition, Product differentiation, Collusion

Bribe markets (MEV)

Domain: Micro / Trading (crypto) Plain English: Mechanism (notably MEV-Boost on Ethereum) in which block builders compete by bidding (effectively bribing) validators to include their proposed block. The "bribe" is the proposer payment in MEV-Boost. Distinct from off-chain bribery; on-chain and protocol-mediated. Why it matters: How MEV revenue is shared among searchers, builders, and proposers post-PBS. Related: MEV (Maximal Extractable Value), MEV-Boost, Builder (Ethereum / PBS), Proposer (Ethereum) See also: covered in 05-trading-theory-and-practice.md §MEV.

CES (Constant Elasticity of Substitution)

Domain: Micro Symbol / formula: Y = [α·K^ρ + (1−α)·L^ρ]^(1/ρ), elasticity = 1/(1−ρ) Plain English: Production or utility function in which the elasticity of substitution between inputs is constant. Nests Cobb-Douglas (ρ=0), Leontief (ρ→−∞), and linear (ρ=1). Workhorse in trade models (Armington, Dixit-Stiglitz) and macro production. Why it matters: The default flexible-form aggregator across micro, trade, and macro modeling. Related: Cobb-Douglas production function, Dixit-Stiglitz aggregator, Elasticity of substitution

CGE model (Computable General Equilibrium)

Domain: Micro / Macro Plain English: Large-scale numerical implementation of a general-equilibrium model — many sectors, agents, taxes, regions — calibrated to a social accounting matrix and used for policy counterfactuals (trade liberalization, carbon tax, immigration reform). Why it matters: Mainstay of think-tank policy analysis when reduced-form evidence is unavailable. Related: General equilibrium, Arrow-Debreu, Deep parameters

Collusion

Domain: Micro Plain English: Explicit or tacit agreement among firms to restrict output, raise prices, or divide markets. Explicit collusion (price-fixing cartels) is per-se illegal; tacit collusion via repeated-game cooperation is harder to prosecute. Folk theorem says cooperation can be sustained as a [[subgame-perfection|subgame-perfect equilibrium]] with sufficient patience. Why it matters: Central concern of antitrust; emerging worry around algorithmic pricing as a collusion facilitator. Related: Cartel, Antitrust, Folk theorem, Bertrand competition

Commitment device

Domain: Micro (behavioral) Plain English: Mechanism that voluntarily restricts future choice to avoid succumbing to temptation or Time inconsistency. Examples: Christmas savings clubs, locked-up retirement accounts, public quit-smoking pledges, [[ve-token|vote-escrowed token locks]]. Why it matters: Standard policy and product response to hyperbolic discounting and self-control problems. Related: Time inconsistency, Hyperbolic discounting, Nudge

Comparative advantage

Domain: Micro / Macro Plain English: Ricardo's principle: countries (or individuals) gain from trade by specializing in goods they produce at lower opportunity cost, even if a partner is absolutely more productive in everything. Generates the textbook case for free trade. Why it matters: Core argument behind trade liberalization; absent imperfect markets, gains from trade are positive in aggregate even if unevenly distributed. Related: Gains from trade, Ricardian model, Heckscher-Ohlin

Complements

Domain: Micro Plain English: Goods are complements if a fall in the price of one raises demand for the other (cross-price elasticity < 0). Hot dogs and buns; software and hardware. In production, factors are complements if a rise in one raises the marginal product of the other. Why it matters: Drives bundling, two-sided market design, and antitrust analysis of "tying." Related: Substitutes, Cross-price elasticity, Bundling

Conspicuous consumption

Domain: Micro (behavioral / sociological) Plain English: Veblen's term for consumption motivated by display of wealth or status rather than direct utility. Generates Veblen goods (demand rises with price) and is observed empirically in luxury and positional goods. Why it matters: Standard counterexample to the law of demand; foundation for status-based models of inequality and growth. Related: Veblen goods, Luxury, Positional goods

Contract theory

Domain: Micro Plain English: Branch of microeconomics analyzing optimal contracts under asymmetric information — moral hazard, adverse selection, and incomplete contracts. Foundational results: Holmström on optimal incentives, Hart-Moore on residual control rights, Tirole on regulation. 2016 Nobel to Hart and Holmström. Why it matters: Backbone of modern corporate governance, executive pay, regulation, and procurement design. Related: Principal-agent problem, Moral hazard, Adverse selection, Incomplete contracts

Cost-benefit analysis

Domain: Micro (public) Plain English: Decision framework that monetizes all costs and benefits of a policy (including non-market goods via Willingness-to-pay) and chooses options where benefits exceed costs. Requires a discount rate and a treatment of distributional weights. Why it matters: Mandatory for major U.S. federal rules (OMB A-4); central in environmental, transportation, and health regulation. Related: Discount rate, Social cost of carbon (SCC), Willingness-to-pay, Kaldor-Hicks efficiency

Cournot competition

Domain: Micro Plain English: Oligopoly model in which firms simultaneously choose quantities and a market-clearing price emerges. Equilibrium output is between monopoly and perfect competition; markups depend on the number of firms and demand elasticity. Why it matters: Workhorse model for industries with capacity-driven competition; underlies HHI-based antitrust intuition. Related: Bertrand competition, Oligopoly, Market power, HHI (Herfindahl-Hirschman Index)

Diminishing returns

Domain: Micro / Macro Plain English: As more of a variable input is added (holding others fixed), the marginal output eventually falls. Standard assumption on production functions, motivating concave Y(K, L) and the Solow steady state. Why it matters: Driver of decreasing marginal product, declining growth at higher capital, and the convergence prediction of neoclassical growth. Related: Production function, Marginal product, Solow model

Discrete choice

Domain: Micro (econometrics) Plain English: Modeling framework for choices among a finite set of alternatives (which car? which job?). Logit and probit derive from random-utility assumptions; BLP extends to differentiated-products demand with endogeneity correction. Why it matters: Backbone of empirical IO, transportation, and labor economics. Related: BLP (Berry-Levinsohn-Pakes), Logit, Mixed logit, Random utility See also: covered in 03-microeconomics-sota.md §Empirical industrial organization.

Discrimination (statistical)

Domain: Micro (labor) Plain English: Differential treatment based on group statistics rather than individual information — e.g., employers using race or gender as a noisy signal of productivity. Distinct from taste-based discrimination (Becker). Bohren-Imas-Rosenberg and Arnold-Dobbie-Yang frameworks formalize accurate vs inaccurate statistical discrimination. Why it matters: Drives empirical debates about whether observed disparities reflect bias or fundamentals; central in audit-study literature. Related: Taste-based discrimination, Bohren-Rosenberg-Imas framework, Becker discrimination

Economic profit

Domain: Micro Plain English: Revenue minus all costs including opportunity costs of capital and owner labor. Zero economic profit in long-run competitive equilibrium means firms earn just enough to keep capital and labor in the industry. Positive economic profit signals Market power or temporary rents. Why it matters: The "profit" of microeconomic theory, distinct from accounting profit. Related: Opportunity cost, Accounting profit, Economic rent

Expected utility

Domain: Micro (decision theory) Symbol / formula: U(L) = Σ_s p_s · u(x_s) Plain English: Von Neumann-Morgenstern framework in which preferences over lotteries are represented by the expected value of a Bernoulli utility function. Requires the Axioms of choice (especially independence). Violated empirically by Allais paradox and Prospect theory. Why it matters: The default model of choice under risk in economics, finance, and game theory. Related: Axioms of choice, Prospect theory, Risk aversion, CRRA (Constant Relative Risk Aversion)

First-price auction

Domain: Micro Plain English: Sealed-bid auction in which the highest bidder wins and pays their own bid. Optimal strategy is to bid below your value (bid shading) because you pay what you bid. Strategically equivalent to a [[auction-dutch|Dutch auction]] under standard assumptions. Why it matters: Common in procurement, treasury auctions (in some countries), and many ad auctions today. Related: Second-price auction, Revenue equivalence theorem, Winner's curse

Free-rider problem

Domain: Micro (public) Plain English: When a good is non-excludable, individuals can enjoy it without paying — so private provision is undersupplied relative to the social optimum. Classic motivation for public-goods provision and taxation. Why it matters: Justifies government provision of defense, basic research, vaccination, and public infrastructure. Related: Public good, Non-excludable, Lindahl pricing

Income elasticity

Domain: Micro Symbol / formula: ε_Y = (∂Q/∂Y) · (Y/Q) Plain English: Percent change in quantity demanded per percent change in income. Positive for normal goods (>1 = Luxury; 0–1 = necessity); negative for inferior goods. Why it matters: Classifies goods (luxury, necessity, inferior) and shapes demand projections under income growth. Related: Elasticity (price of demand), Luxury, Inferior good, Engel curve

Labor market concentration

Domain: Micro (labor) Plain English: HHI of employers within a local labor market. Azar-Marinescu-Steinbaum and others show many U.S. local markets are concentrated; theoretical wage suppression in monopsony models is large. Empirical wage effects are debated but the literature now supports modest but non-zero monopsony power even in low-skill labor markets. Why it matters: Motivates noncompete bans, merger review's labor-market lens, and minimum-wage debates. Related: Monopsony, Minimum wage, HHI (Herfindahl-Hirschman Index), Noncompete See also: covered in 03-microeconomics-sota.md §Labor monopsony.

Labor supply elasticity

Domain: Micro (labor) Plain English: Percent change in hours worked (or labor-force participation) per percent change in the after-tax wage. Intensive-margin elasticities are typically small (0.1–0.3 for prime-age men, larger for secondary earners); extensive-margin elasticities are larger. Why it matters: Determines deadweight loss of income taxation and the labor-supply response to welfare reform, EITC, and minimum wage. Related: Frisch elasticity, EITC (Earned Income Tax Credit), Optimal taxation (Mirrlees)

Luxury

Domain: Micro Plain English: Good whose income elasticity exceeds 1 — consumption rises faster than income. Cars, restaurant meals, designer apparel. Distinct from Conspicuous consumption and Veblen goods. Why it matters: Sector-level demand projections, tariff design, and tax incidence depend on luxury vs necessity classification. Related: Income elasticity, Engel curve, Veblen goods

Market power

Domain: Micro Plain English: Ability of a firm or group to set price above marginal cost. Measured by the Lerner index (P − MC)/P, by markup ratios (De Loecker-Eeckhout), or by HHI proxies. Rising aggregate markups documented in U.S. data post-1980 by De Loecker-Eeckhout-Unger (contested by Traina, Basu). Why it matters: Central to antitrust, inequality narratives, and macro distributional debates. Related: Lerner index, Markup, Antitrust, Natural monopoly See also: covered in 03-microeconomics-sota.md §Rising markups.

Matching function

Domain: Micro / Macro (labor) Symbol / formula: M = M(U, V), often Cobb-Douglas Plain English: Aggregate matching technology mapping unemployed workers (U) and vacancies (V) into hires (M). Used in Diamond-Mortensen-Pissarides search-and-matching models. Beveridge curve is the V-U trace of this function. Why it matters: Foundation of modern labor macro and the workhorse for analyzing unemployment dynamics. Related: Search and matching, Beveridge curve, DMP model (Diamond-Mortensen-Pissarides), V/U ratio

Minimum wage

Domain: Micro (labor) Plain English: Statutory floor on hourly compensation. Card-Krueger 1994 and subsequent literature found small or zero disemployment effects at moderate increases; Cengiz-Dube-Lindner-Zipperer bunching estimator confirmed small employment effects through 2018. Debate concerns very large increases (e.g., $15+ in low-cost areas). Why it matters: One of the most-tested policies in labor economics; central in monopsony and inequality debates. Related: Monopsony, Card-Krueger minimum-wage study, Bunching estimator, Labor market concentration

Mirrlees rule

Domain: Micro (public) Plain English: Optimal nonlinear income tax characterization from Mirrlees (1971): at any income, the marginal tax rate balances the redistributive benefit against the labor-supply distortion. The Saez (2001) version expresses the top rate in terms of three elasticities: behavioral, top-income share, and social marginal welfare weight. Why it matters: The reference framework for thinking about optimal top tax rates. Related: Optimal taxation (Mirrlees), Saez formula, Labor supply elasticity See also: covered in 03-microeconomics-sota.md §Optimal taxation.

Natural monopoly

Domain: Micro Plain English: Industry where a single firm can serve the whole market at lower cost than two or more (declining average cost over the relevant range). Examples: water distribution, electricity transmission, local gas. Standard policy response: regulate price or impose access obligations. Why it matters: Justifies regulation rather than competition in network industries. Related: Market power, Economies of scale, Regulation

Perfect competition

Domain: Micro Plain English: Idealized market with many small price-taking firms, homogeneous products, free entry/exit, and full information. Long-run equilibrium has price = marginal cost = minimum average cost, zero economic profit. Useful benchmark; rarely literal. Why it matters: The reference point against which market power and welfare losses are measured. Related: Market power, Economic profit, Welfare theorems (first and second)

Probability weighting

Domain: Micro (behavioral) Plain English: In Prospect theory, decision weights are a nonlinear function of probabilities — small probabilities are overweighted, large ones underweighted. Generates simultaneous gambling (overpaying for lottery tickets) and insurance (overpaying to avoid tiny disasters). Why it matters: Explains long-tail option pricing biases, lottery participation, and over-insurance. Related: Prospect theory, Reference dependence, Loss aversion

Product differentiation

Domain: Micro Plain English: Real or perceived differences across products in the same market — horizontal (location, taste) or vertical (quality). Generates downward-sloping firm demand and markups even with many competitors. Modeled via Hotelling, Dixit-Stiglitz, or random-utility discrete choice. Why it matters: Reason most real markets have markups and persistent firm-level returns; backbone of empirical IO demand estimation. Related: Bertrand competition, Discrete choice, BLP (Berry-Levinsohn-Pakes), Hotelling line

Property rights

Domain: Micro Plain English: Legal and de facto allocation of rights to use, exclude others from, and transfer assets. Per Coase theorem, with low transaction costs and well-defined rights, bargaining achieves efficient allocations regardless of initial assignment. North-Acemoglu-Robinson literature: secure property rights are necessary for long-run growth. Why it matters: Foundational institution; weak property rights are a leading explanation for development failures. Related: Coase theorem, Institutions, Acemoglu-Robinson framework

Reference dependence

Domain: Micro (behavioral) Plain English: People evaluate outcomes relative to a reference point (often the status quo or an expectation) rather than in absolute terms. Combined with Loss aversion (losses hurt more than equivalent gains feel good), it is the core of Prospect theory. Why it matters: Drives endowment effect, sticky wages, asymmetric reaction to gains/losses, and disposition effect in trading. Related: Prospect theory, Loss aversion, Endowment effect, Anchoring

Replicator dynamics

Domain: Micro (evolutionary game theory) Plain English: Differential equation describing how strategy shares in a population evolve over time — strategies with above-average payoffs grow, below-average shrink. Pioneered by Taylor-Jonker and Maynard Smith; converges to evolutionarily stable strategies (ESS) in many games. Why it matters: Foundation of evolutionary game theory and a useful model for adaptive learning in markets. Related: Evolutionarily stable strategy (ESS), Nash equilibrium, Learning in games

Reputation

Domain: Micro (game theory) Plain English: In repeated games or games with incomplete information about a player's type, behavior today shapes others' beliefs about that player tomorrow. Kreps-Milgrom-Roberts-Wilson (1982) showed reputation effects sustain cooperation even with a small probability of a "committed" type. Why it matters: Explains how trust and cooperation arise without explicit contracts; central in chain-store paradox, monetary policy credibility, and market making. Related: Repeated games, Folk theorem, Time inconsistency

Second-price auction

Domain: Micro Plain English: Sealed-bid auction in which the highest bidder wins but pays the second-highest bid. Truthful bidding (bid your true value) is a dominant strategy. Foundation of VCG mechanism (Vickrey-Clarke-Groves) and modern ad auction theory. Why it matters: Theoretical workhorse and basis of Vickrey, generalized second-price, and VCG-based mechanisms. Related: First-price auction, VCG mechanism (Vickrey-Clarke-Groves), Revenue equivalence theorem

Subgame perfection

Domain: Micro (game theory) Plain English: Refinement of Nash equilibrium for extensive-form games: strategies must constitute a Nash equilibrium in every subgame, not just the whole game. Eliminates non-credible threats. Found via Backward induction in finite games of perfect information. Why it matters: Standard equilibrium concept for sequential games; rules out empty threats. Related: Nash equilibrium, Backward induction, Extensive-form game

Substitutes

Domain: Micro Plain English: Goods are substitutes if a rise in the price of one increases demand for the other (cross-price elasticity > 0). Coke and Pepsi; train and plane. In production, factors are substitutes if a rise in one factor's price raises demand for the other. Why it matters: Shapes market-definition decisions in antitrust, cross-price elasticity estimation, and CES production specifications. Related: Complements, Cross-price elasticity, CES (Constant Elasticity of Substitution)

Sunk cost fallacy

Domain: Micro (behavioral) Plain English: Tendency to let past, irrecoverable costs influence current decisions — "we've already spent so much, we should finish." Economically, sunk costs should not affect forward-looking choices. Why it matters: Drives over-commitment in projects, escalation in bad investments, and "throwing good money after bad" patterns in capital budgeting and trading. Related: Loss aversion, Behavioral economics, Escalation of commitment

Switching costs

Domain: Micro Plain English: Costs (financial, contractual, or behavioral) of changing supplier or platform. Generates lock-in, downward-sloping firm-level demand, and "bargains then ripoffs" pricing patterns (Klemperer). Critical in software, telecoms, and financial services. Why it matters: A leading explanation for persistent markups and customer inertia; antitrust-relevant when entry-deterring. Related: Lock-in, Market power, Network effects (direct vs indirect)

Tax incidence

Domain: Micro (public) Plain English: Distribution of the economic burden of a tax, not the statutory remitter. Burden falls more heavily on the more inelastic side of the market. Payroll-tax incidence: largely on workers despite half being remitted by employers. Why it matters: Statutory burden and economic burden differ; tax-design debates hinge on incidence rather than legal label. Related: Deadweight loss, Elasticity (price of demand), Optimal taxation (Ramsey) See also: covered in 03-microeconomics-sota.md §Public finance.

Welfare economics

Domain: Micro Plain English: Subfield analyzing when market outcomes are efficient and how policy can improve social welfare. Includes the two Welfare theorems (first and second), deadweight loss measurement, social welfare functions, and the sufficient-statistics approach. Distinct from "welfare programs" (transfers). Why it matters: Provides the normative framework for evaluating any market intervention. Related: Welfare theorems (first and second), Deadweight loss, Sufficient statistics approach, Social welfare function

Macroeconomics — second batch

All Weather

Domain: Trading / Macro Plain English: Bridgewater's flagship risk-parity portfolio (Ray Dalio, mid-1990s) designed to perform across all four growth × inflation regimes. Classic mix: ~30% equities, 55% Treasuries (split long and intermediate), 15% gold and commodities, levered to equity-equivalent volatility. SPDR/Bridgewater ALLW ETF launched March 2025. Why it matters: Canonical implementation of Risk parity; widely-copied institutional allocation template. Related: Risk parity, Max diversification, 60/40 See also: covered in 05-trading-theory-and-practice.md §Risk parity.

Balance sheet channel

Domain: Macro Plain English: Mechanism by which monetary policy affects borrower net worth — higher rates reduce asset prices and collateral values, raising the External finance premium and constraining credit. Bernanke-Gertler-Gilchrist formalized this within the Credit channel family. Especially powerful for SMEs and consumer credit. Why it matters: Explains why monetary policy bites harder when balance sheets are weak (e.g., 2008, post-COVID SMEs). Related: Credit channel, Bank lending channel, External finance premium

Campbell's Law

Domain: Macro / Multi Plain English: Donald Campbell's principle: the more a quantitative indicator is used for high-stakes decisions, the more it will be gamed and the less it will measure what it was supposed to measure. Macro/finance examples: Goodhart's law variant for monetary aggregates, Volcker-era M1 targeting, regulatory capital arbitrage. Why it matters: Cautionary against rigid rules tied to measured indicators that can be manipulated. Related: Goodhart law, Lucas critique

Capital consumption allowance

Domain: Macro Plain English: National-accounts term for depreciation of fixed capital — the wear-and-tear cost subtracted from GDP to arrive at Net Domestic Product. Conceptually important; subject to large measurement uncertainty especially for intangible capital. Why it matters: Determines net (vs gross) saving and investment figures used in growth and welfare accounting. Related: Deflator (GDP), NDP (Net Domestic Product), Depreciation

Capital controls

Domain: Macro (international) Plain English: Government restrictions on cross-border capital flows — taxes, quotas, licensing. Once dismissed by the IMF, partly rehabilitated post-2008 in the IMF's "institutional view" as a legitimate tool against capital-flow surges. Used heavily in China, India, and some EMs. Why it matters: Crucial for the Trilemma (international finance) — open capital + fixed FX + independent monetary policy is impossible. Related: Trilemma (international finance), Sudden stop, Currency crisis (first / second / third generation)

Carhart four-factor model

Domain: Trading / Macro (asset pricing) Symbol / formula: R_i − R_f = α + β_MKT(R_m − R_f) + β_SMB·SMB + β_HML·HML + β_MOM·MOM + ε Plain English: Mark Carhart (1997) added a momentum factor (MOM / UMD) to Fama-French 3-factor. Once you control for momentum, persistence in mutual-fund performance largely disappears — "hot hands" are usually just funds riding a momentum theme. Why it matters: Standard performance attribution model; momentum is the most reliably-replicated of the post-CAPM factors. Related: Fama-French, MOM (momentum factor), Momentum effect, HML (High Minus Low), SMB (Small Minus Big) See also: covered in 05-trading-theory-and-practice.md §Factor models.

Credit channel

Domain: Macro Plain English: Bernanke-Gertler-Gilchrist family of mechanisms by which monetary policy operates through credit-market frictions, not just the standard interest-rate channel. Splits into the Bank lending channel (supply of bank credit) and the Balance sheet channel (borrower net worth). Important when financial frictions are large. Why it matters: Standard explanation for why credit conditions amplify business cycles and crises. Related: Bank lending channel, Balance sheet channel, Financial accelerator

Discretionary fiscal policy

Domain: Macro Plain English: Active changes in tax rates or spending decided by legislators, as opposed to Automatic stabilizers (programs that respond mechanically to the business cycle). Discretionary actions include the 2020 CARES Act, 2008 ARRA, and Reagan 1981 tax cuts. Why it matters: Subject to long inside lags (legislation) and political constraints; multiplier estimates are contested. Related: Automatic stabilizers, Fiscal multiplier, Fiscal stimulus

Distributional effects of monetary policy

Domain: Macro Plain English: How monetary actions affect different households unequally — through asset prices (favoring asset holders), wage and employment dynamics (favoring workers when easing), debt servicing costs, and rents. HANK models make these explicit; pre-HANK representative-agent models could not address them. Why it matters: Reshapes the politics of monetary policy and the design of mandate debates (employment-focused vs price-focused frameworks). Related: HANK (Heterogeneous Agent New Keynesian), Cantillon effect, K-shaped recovery

Dollarization

Domain: Macro (international) Plain English: Adoption of a foreign currency (typically the USD) as legal tender or as the dominant transaction and savings currency. Examples: Ecuador (2000), El Salvador (2001), large unofficial dollarization in Argentina and Lebanon. Eliminates currency risk but surrenders monetary sovereignty. Why it matters: Sometimes the only credible anchor for high-inflation EMs; relevant for the modern stablecoin debate. Related: Currency crisis (first / second / third generation), Trilemma (international finance), Lender of last resort (LoLR)

Endogenous growth

Domain: Macro Plain English: Family of growth models (Romer 1990, Aghion-Howitt 1992) in which long-run growth rates depend on choices — R&D, education, institutions — rather than being pinned down by exogenous technological progress as in Solow. Knowledge spillovers and increasing returns drive sustained growth. Why it matters: Provides the theoretical case that policy can affect long-run growth rates, not just levels. Related: Solow model, Romer growth, Aghion-Howitt framework, Total factor productivity (TFP)

Engle-Granger

Domain: Macro (econometrics) Plain English: Two-step procedure (Engle-Granger 1987) for testing cointegration between two non-stationary time series: regress one on the other, then test the residual for stationarity. Modern practice uses the Johansen test for multivariate cointegration. Why it matters: Workhorse for testing long-run equilibrium relations (PPP, term structure, money demand). Related: Cointegration, Johansen test, Error correction model

Exchange rate regime

Domain: Macro (international) Plain English: A country's policy for the nominal exchange rate — free float (US, EU, UK, Japan), managed float (most EMs), crawling peg, hard peg (HK, dollarization). IMF AREAER classifies regimes annually. Choice shapes monetary autonomy (Trilemma (international finance)) and crisis vulnerability. Why it matters: Foundational macro choice; determines what shocks the economy absorbs vs propagates. Related: Trilemma (international finance), Currency crisis (first / second / third generation), Capital controls, Currency board

Expectations hypothesis (term structure)

Domain: Macro / Trading Plain English: Idea that long rates equal the expected average of future short rates (plus a constant). Rejected empirically — long rates contain a time-varying Term premium. Still a useful first approximation in policy talk. Why it matters: Frames the breakdown into "expected rates" and "term premium" that dominates Treasury market analysis. Related: Term premium, Yield curve, Forward rate

External validity

Domain: Macro / Micro (methodology) Plain English: Whether a finding from one setting (a particular RCT, country, period) generalizes to another. A pervasive concern in the credibility revolution — site selection bias (List), heterogeneous treatment effects, scaling problems all threaten external validity even when internal validity is strong. Why it matters: Determines whether reduced-form estimates can guide policy beyond the immediate sample. Related: Internal validity, Site-selection bias, LATE vs ATE, Heterogeneous treatment effects

Fama-French

Domain: Trading / Macro (asset pricing) Plain English: Three-factor (1993) and later five-factor (2015) asset-pricing models extending CAPM. Original 3-factor: market, SMB (Small Minus Big) (size), HML (High Minus Low) (value). 5-factor adds profitability (RMW) and investment (CMA). Workhorse benchmark for performance attribution. Why it matters: The standard alternative to CAPM; basis of factor-investing ETF industry. Related: CAPM (Capital Asset Pricing Model), Carhart four-factor model, HML (High Minus Low), SMB (Small Minus Big), Hou-Xue-Zhang (q-factor model) See also: covered in 05-trading-theory-and-practice.md §Factor models.

Financial account

Domain: Macro (international) Plain English: BoP component capturing cross-border financial-asset transactions — FDI, portfolio investment, other investment (loans, deposits), reserve assets. The big mover in BoP for advanced economies. Mirror image of the Current account. Why it matters: Tracks where saving goes globally; foundation of "global saving glut" and capital-flow analysis. Related: Balance of payments (BoP), Current account, Capital controls

GDP deflator

Domain: Macro Plain English: Implicit price index = nominal GDP / real GDP. Broader than CPI because it covers all domestically produced output, including investment goods, government services, and exports. Chain-weighted in U.S. NIPA. Why it matters: Standard measure of economy-wide inflation; differs from CPI mainly because of housing weights and the inclusion of investment goods. Related: CPI (Consumer Price Index), PCE deflator, Real GDP

GNI (Gross National Income)

Domain: Macro Plain English: GDP plus net income earned by domestic residents from abroad (factor incomes net of factor payments). Differs from GDP in places like Ireland, Singapore, and Luxembourg where large multinational operations distort GDP. UN preferred indicator for per-capita income comparisons. Why it matters: A truer measure of national economic welfare than GDP when foreign-owned production is large. Related: Deflator (GDP), GNP (Gross National Product), Net factor income

Great Gatsby curve

Domain: Macro / Micro (inequality) Plain English: Empirical regularity (Krueger 2012) that countries with higher income inequality also have lower intergenerational income mobility. Suggested mechanism: inequality begets institutions and investment patterns that perpetuate it. Why it matters: Frames the inequality-mobility nexus that motivates much modern policy debate. Related: Intergenerational elasticity of income, Gini coefficient, Top share (income / wealth)

Heckman selection

Domain: Micro / Macro (econometrics) Plain English: Two-step correction (Heckman 1979) for sample selection bias — when the sample observed depends on the outcome being studied (e.g., wages observed only for those who work). First stage models selection (probit); second stage adds the inverse Mills ratio to the outcome regression. Why it matters: Foundational correction; informed entire generation of empirical work on labor force participation, immigration, and treatment effects. Related: Selection bias, Inverse Mills ratio, LATE (local average treatment effect)

Hou-Xue-Zhang (q-factor model)

Domain: Trading / Macro (asset pricing) Plain English: 4-factor model (Hou, Xue, Zhang 2015) grounded in q-theory: market, size, investment-to-assets (low minus high), and profitability. Explains roughly half of the ~80 anomalies tested against it and often beats Fama-French 5-factor head-to-head. Why it matters: Major modern competitor to Fama-French; reduces the "factor zoo" significantly. Related: Hou-Xue-Zhang (q-factor model), Fama-French, Factor zoo See also: covered in 05-trading-theory-and-practice.md §Factor models.

Johansen test

Domain: Macro (econometrics) Plain English: Maximum-likelihood test (Johansen 1988, 1991) for the number of cointegrating relationships in a multivariate vector of non-stationary series. Generalizes Engle-Granger to multivariate settings. Why it matters: Standard tool for multivariate cointegration analysis in time-series macro and finance. Related: Cointegration, Engle-Granger, VECM (Vector Error Correction Model)

Kalecki markup

Domain: Macro (heterodox) Plain English: Michał Kalecki's view of price-setting: prices are set as a markup over unit prime costs, where the markup reflects the firm's "degree of monopoly." Reintroduced into modern policy debate during 2022–23 inflation as ""Sellers' inflation"" / "greedflation" — though mainstream analyses (ECB, BIS) attribute only modest shares of inflation to markup expansion. Why it matters: Foundation of heterodox markup-driven inflation views; revived in post-COVID inflation debate. Related: "Sellers' inflation", Markup, Market power

Lender of last resort (LoLR)

Domain: Macro Plain English: Bagehot's classic prescription (1873): in a panic, lend freely against good collateral at a penalty rate. The central-bank function of providing emergency liquidity to solvent-but-illiquid institutions. Discount window in the U.S.; ECB's MRO/LTRO; BoE's DWF and CTRF. Why it matters: Distinguishes liquidity support (legitimate) from solvency support (politically fraught) in crises. Related: Discount window, Bagehot rule, Primary credit rate

LIBOR transition

Domain: Macro / Trading Plain English: 2017–2023 effort to replace LIBOR (London Interbank Offered Rate) with risk-free benchmarks — SOFR in USD, SONIA in GBP, €STR in EUR, TONA in JPY. USD LIBOR ceased June 2023; legacy contracts use ARRC fallback spreads. Why it matters: Largest financial-contract transition in history; reshaped derivatives, mortgages, and corporate lending benchmarks. Related: SOFR (Secured Overnight Financing Rate), OATs OIS (spread), Swap (interest rate / swap-interest-rate)

Longer-run projections

Domain: Macro Plain English: SEP (Summary of Economic Projections) component published by the FOMC giving each participant's view of the long-run policy rate, unemployment rate, and inflation rate — i.e., their estimate of the steady-state economy. The median long-run rate is the FOMC's r-star (r*) proxy. Why it matters: The closest official statement of where the FOMC thinks the economy is heading; closely watched in r-star debates. Related: Dot plot (SEP), r-star (r*), Dot plot (SEP)

M1 / M2

Domain: Macro Plain English: Standard monetary aggregates: M1 = currency + demand deposits + (since May 2020) most savings deposits; M2 = M1 + small time deposits + retail MMFs. Loose relationship to inflation post-1990; spiked in 2020–21 with QE/fiscal then deflated 2022–23. Why it matters: Once central in monetary policy targeting; now a diagnostic rather than a target. Related: Monetary base, QE (Quantitative Easing), Velocity of money

Multiple testing

Domain: Macro / Trading (methodology) Plain English: When testing many hypotheses, conventional p-value thresholds produce many false positives. Bonferroni, Benjamini-Hochberg, and Harvey-Liu-Zhu propose stricter thresholds. In asset pricing, Harvey-Liu-Zhu argued the t-stat hurdle for new factors should be raised from 2.0 to 3.0. Why it matters: Core methodological issue in the "factor zoo" debate and in empirical macro. Related: Harvey-Liu-Zhu, Factor zoo, Deflated Sharpe ratio (Bailey-López de Prado), Purged k-fold CV

Narrative identification

Domain: Macro (econometrics) Plain English: Empirical-macro strategy that uses textual/narrative records (FOMC minutes, central-bank communication, news coverage) to isolate exogenous shocks — Romer-Romer monetary shocks, Cloyne-Hürtgen tax shocks, Bloom-style uncertainty news. Avoids reliance on identifying restrictions in [[var-econometrics|VARs]]. Why it matters: Modern alternative to recursive/sign restrictions for identifying structural shocks. Related: Romer-Romer, Uncertainty shock, VAR-econometrics (Vector Autoregression)

Oil shock

Domain: Macro Plain English: Large, sudden change in oil prices — 1973 OPEC embargo, 1979 Iran revolution, 1990 Gulf War, 2008 spike, 2014–16 collapse, 2022 post-Ukraine surge. Operate as classic [[supply-shock|supply shocks]] (output down, prices up) in the AS-AD frame; modern analyses also account for demand-driven oil moves (Kilian decomposition). Why it matters: Recurring driver of stagflation episodes; Kilian decomposition is standard tool for parsing demand vs supply oil shocks. Related: Supply shock, Stagflation, Kilian decomposition

Primary credit rate

Domain: Macro Plain English: Interest rate the Federal Reserve charges on overnight loans to depository institutions at the discount window's primary-credit program. Set above IORB (Interest on Reserve Balances) (the "penalty rate"), it acts as a ceiling on overnight rates. Took on new visibility during March 2023 banking stress. Why it matters: Operational ceiling in the Fed's floor system; lender-of-last-resort price. Related: Discount window, SRF (Standing Repo Facility), Lender of last resort (LoLR)

Rare disaster

Domain: Macro / Trading (asset pricing) Plain English: Rietz (1988), Barro (2006) approach: low-probability large drops in consumption (wars, depressions, pandemics) generate the observed equity premium and risk-free rate without implausible risk aversion. Wachter (2013) variants with time-varying disaster risk match more moments. Why it matters: Mainstream resolution of the equity-premium puzzle that also explains tail-risk pricing. Related: Equity premium puzzle, Tail risk, Barro

Reduced form

Domain: Macro / Micro (econometrics) Plain English: An estimating equation that maps observables to outcomes without explicitly modeling underlying structural mechanisms. Contrasts with [[structural-model|structural models]] that estimate Deep parameters. Reduced-form work dominated the "credibility revolution" but is vulnerable to the Lucas critique. Why it matters: Reduced-form clarity vs structural extrapolation tension is the central methodological debate in modern empirical economics. Related: Deep parameters, Lucas critique, Structural model, Sufficient statistics approach

Repo run

Domain: Macro / Trading Plain English: Sudden withdrawal of secured funding in the repo market — counterparties refuse to roll, demand higher haircuts, or stop accepting certain collateral. Bear Stearns and Lehman 2008 are textbook cases; September 2019 repo spike was a non-systemic version. Foundation of Gorton's "shadow banking" crisis narrative. Why it matters: Repo runs are the modern equivalent of bank runs for shadow banking and the wholesale funding system. Related: Repo (repurchase agreement), Shadow banking / NBFI, Funding liquidity, Run on a fund

Repo specials

Domain: Macro / Trading Plain English: A specific Treasury issue trading at a repo rate well below the [[gc-repo|general collateral]] rate — because demand to borrow that exact security (typically to cover a short) exceeds supply. "On special" can imply repo rates near zero or negative. Common around Treasury auction cycles and Fed operations. Why it matters: Diagnostic of bond-market squeezes and short positioning; relevant in Treasury basis trade economics. Related: GC repo, Treasury basis trade, Hard-to-borrow

Resolution planning

Domain: Macro Plain English: Dodd-Frank requirement that large banks ("living wills") and FSB G-SIBs submit credible plans for orderly wind-down without taxpayer support. Failure to demonstrate resolvability triggers structural remedies. SVB's failure (March 2023) reopened debate about resolution adequacy for mid-sized banks. Why it matters: Backbone of the "no more bailouts" post-2008 regime; structurally shapes bank balance sheets. Related: G-SIB / D-SIB (gsib / dsib), TLAC (Total Loss-Absorbing Capacity), Orderly Liquidation Authority (OLA)

Run on a fund

Domain: Macro / Trading Plain English: Investor stampede out of an open-ended fund whose underlying assets are less liquid than the redemption terms — prime MMFs September 2008, UK LDI September 2022, gated property funds. The fund must fire-sale to meet redemptions, harming remaining holders and possibly amplifying stress. Why it matters: Key NBFI fragility identified by the FSB; motivates swing pricing, MMF reform, and LCR-style buffers for non-banks. Related: MMF reform, Gates and fees, Swing pricing, LDI crisis

Sticky prices

Domain: Macro Plain English: Empirical regularity that nominal prices adjust slowly — average price duration ~4–9 months across studies (Bils-Klenow, Nakamura-Steinsson). Modeled via Calvo (random reset), Taylor (staggered), or menu-cost (state-dependent) formulations. Foundational to [[new-keynesian-model|NK models]]. Why it matters: The crucial ingredient that gives monetary policy real effects in NK macro. Related: Calvo pricing, Menu cost, Sticky information, Rational inattention

Stagflation

Domain: Macro Plain English: Simultaneous high inflation and high unemployment (often with stagnant growth). Hallmark of the 1970s in the U.S. — oil shocks, accommodative policy, declining productivity. Briefly invoked during 2022 but real wages and growth held up better than 1970s analogues. Why it matters: The reference scenario for accidental policy in supply-shock regimes; Volcker-disinflation analogue. Related: Oil shock, Supply shock, Phillips curve, Volcker disinflation

Time inconsistency

Domain: Macro / Micro Plain English: Kydland-Prescott (1977): the optimal policy chosen today differs from what the same policymaker would re-optimize to do later when constraints have changed. Generates inflation bias if a central bank has discretion; motivates rules, [[commitment-device|commitment devices]], and inflation-targeting frameworks. Why it matters: Theoretical backbone for central-bank independence and inflation-targeting regimes. Related: Lucas critique, Rules vs discretion, Commitment device

Trade-weighted dollar

Domain: Macro Plain English: USD value against a basket of trading-partner currencies, weighted by trade share. Fed publishes broad and narrow indices. The "DXY" (ICE Dollar Index) is a 1973-vintage 6-currency basket; the Fed's broad index is more current. Why it matters: Standard summary of USD strength; correlates with commodity prices, EM stress, and Treasury demand. Related: NEER and REER (neer-reer / Nominal and Real Effective Exchange Rate), DXY (Dollar Index)

Two-way fixed effects (TWFE)

Domain: Macro / Micro (econometrics) Plain English: Standard differences-in-differences specification with unit and time fixed effects. Recent econometrics literature (de Chaisemartin-D'Haultfœuille, Goodman-Bacon, Borusyak-Jaravel-Spiess) showed TWFE can produce misleading estimates with staggered treatment timing and heterogeneous effects; new estimators (DCDH, Sun-Abraham, BJS) preferred. Why it matters: Workhorse of policy evaluation; recent critiques have shifted standard practice. Related: Diff-in-diff, Parallel trends, Event study, Staggered adoption

Uncertainty shock

Domain: Macro Plain English: Sharp rise in measured uncertainty (VIX, EPU index, dispersion of forecasts) treated as a structural shock. Bloom (2009) showed VIX jumps cause output drops as firms delay hiring and investment. Distinct from first-moment shocks to demand or supply. Why it matters: Modern explanation for recession dynamics around 9/11, 2008, COVID, and policy crises. Related: VIX, EPU index (Economic Policy Uncertainty), Real options, Bloom 2009

VAR-econometrics (Vector Autoregression)

Domain: Macro (econometrics) Plain English: Sims (1980) framework treating macro variables as jointly determined by lags of themselves and the others, with no a priori restrictions. Structural identification via recursive/sign/long-run/IV/narrative restrictions reveals impulse responses to shocks. Bedrock of empirical macro. Why it matters: Standard tool for impulse-response analysis and macro shock identification. Related: SVAR (Structural VAR), Impulse response function (IRF), Sign restrictions, Narrative identification

Wage growth

Domain: Macro Plain English: Year-over-year change in nominal wages. Major series: Employment Cost Index (ECI, quarterly, comprehensive), Average Hourly Earnings (AHE, monthly, sensitive to composition), Atlanta Fed Wage Tracker (job-stayer focus). Fed watches all three for Second-round effects in inflation. Why it matters: Single most-watched real-side indicator of inflation persistence. Related: Atlanta Fed wage tracker, Employment Cost Index (ECI), Phillips curve

Trading — second batch

2SLS (Two-stage least squares)

Domain: Multi (econometrics) Plain English: Standard instrumental-variable estimator: regress the endogenous variable on instruments (first stage), then regress the outcome on the fitted values (second stage). Consistent if the instrument satisfies relevance and the Exclusion restriction. Why it matters: Workhorse IV estimator across empirical micro, macro, and asset pricing. Related: Instrumental variable (IV), Exclusion restriction, LATE (local average treatment effect)

Arbitrage-free pricing

Domain: Trading Plain English: Pricing principle that no portfolio should generate riskless profit from a zero initial outlay. Equivalent (by the First Fundamental Theorem of Asset Pricing) to existence of a positive [[risk-neutral-pricing|risk-neutral measure]]. Foundation of derivative pricing. Why it matters: Underpins Black-Scholes, swap pricing, futures-cash parity, and any model that produces "fair value." Related: Risk-neutral pricing, Law of one price, Fundamental theorem of asset pricing See also: covered in 05-trading-theory-and-practice.md §Derivative pricing.

AT1 / CoCo (at1-coco / Additional Tier 1 / contingent convertible)

Domain: Trading Plain English: Bank-regulatory capital instruments that convert to equity or are written down when a trigger (typically CET1 below a threshold) is hit. Counted as Tier 1 capital under Basel III. Famously written down to zero in the March 2023 Credit Suisse / UBS rescue, ahead of equity holders — a contested precedent. Why it matters: Largest bank-issued risk capital; pricing reflects bail-in risk and regulatory discretion. Related: Basel III / IV, TLAC (Total Loss-Absorbing Capacity), Bail-in, SVB-style duration risk

Best execution

Domain: Trading Plain English: Broker-dealer obligation to execute client orders on terms most favorable to the client — price, speed, likelihood of execution, total cost. In the U.S., FINRA Rule 5310 and SEC's 2024 Reg Best Ex; in the EU, MiFID II Article 27. Compliance is data-driven, with venue-by-venue execution-quality reports. Why it matters: Defines the fiduciary boundary on PFOF and internalization; central in retail brokerage debates. Related: PFOF (Payment for Order Flow), Internalization, Order Protection Rule, NBBO (National Best Bid and Offer)

Cap and floor (cap-floor / interest rate)

Domain: Trading Plain English: Series of caplets (calls on a forward rate) or floorlets (puts) struck at a fixed rate. A cap pays the buyer when the floating rate exceeds the strike; a floor pays when it falls below. Standard hedging instrument for floating-rate borrowers and lenders. Why it matters: Building block of rate-risk hedging and the volatility surface of the swap market. Related: Swaption, Swap (interest rate / swap-interest-rate), Caplet

Capital structure arbitrage (capital-structure-arb)

Domain: Trading Plain English: Hedge-fund strategy that takes offsetting positions in a single issuer's different securities (equity vs CDS, senior vs subordinated debt, AT1 vs equity) when their relative pricing diverges from a structural model. Merton-style framework links equity vol to default risk. Why it matters: Distressed-credit and corporate-event playbook; large blow-ups (notably 2005 Ford/GM credit downgrade) have occurred when relationships broke down. Related: Merton model, CDS (Credit Default Swap), Risk arb, Distressed debt

Charm

Domain: Trading (options) Symbol / formula: Charm = ∂Δ/∂τ Plain English: Second-order options Greek measuring how delta changes with the passage of time. Important for dealer hedging into expiry — large gamma + charm flows are blamed for late-day index moves on monthly OPEX. Why it matters: Component of the "vanna/charm" dealer flow narrative in equity-index dynamics. Related: Vanna / charm / vomma, Vanna / charm / vomma, Greeks (options Greeks), Gamma

Colocation

Domain: Trading Plain English: Renting rack space adjacent to an exchange's matching engine to minimize signal-travel latency. Exchanges (NYSE/Mahwah, Nasdaq/Carteret, CME/Aurora) sell these slots; equal-distance cabling ensures fairness across colo customers. Why it matters: Foundational HFT infrastructure; latency advantages of microseconds are worth millions in annual revenue. Related: HFT (High-Frequency Trading), Latency arbitrage, Microwave links

Constant product (AMM)

Domain: Trading (crypto) Symbol / formula: x · y = k Plain English: Pricing rule used by Uniswap V2 and copycats: the product of reserves of two tokens in a pool stays constant during swaps. The marginal price is the ratio of reserves; deeper pools have lower slippage. Uniswap V3 added [[tick-uniswap|concentrated liquidity]] over price ranges. Why it matters: The foundational DEX pricing function; reference point for Impermanent loss (divergence loss) math. Related: AMM (Automated Market Maker), Tick (Uniswap V3 / tick-uniswap), Impermanent loss (divergence loss), Uniswap See also: covered in 05-trading-theory-and-practice.md §AMMs.

Conversion factor (futures)

Domain: Trading Plain English: Multiplier used in Treasury futures to standardize different deliverable bonds to a 6% notional coupon — the invoice price the short pays is (futures price × conversion factor) + accrued. The basis between cash bond and futures × CF is the engine of the Treasury basis trade. Why it matters: Mechanical link between deliverable cash bonds and the futures contract; critical for basis trading and CTD selection. Related: Treasury basis trade, CTD (Cheapest to Deliver), Future (futures contract)

Corporate bond

Domain: Trading Plain English: Debt security issued by a non-financial or financial corporation, paying periodic coupons and principal at maturity. Differs from sovereigns in carrying material credit risk; priced over Treasuries as a spread reflecting probability of default × loss given default plus liquidity premium. ~$11T outstanding in U.S. Why it matters: Largest single fixed-income asset class for corporates; the primary funding instrument outside bank lending. Related: OAS (Option-Adjusted Spread), Credit spread, Fallen angel, Investment grade

Cost of equity

Domain: Trading Plain English: Required return that equity investors demand for holding a company's stock. Estimated via CAPM (R_f + β·ERP), Fama-French/Carhart, or dividend-growth model. Used in DCF valuation as the equity discount rate or as a component of WACC (Weighted Average Cost of Capital). Why it matters: Determines firm valuation, hurdle rate for new projects, and cost-of-capital comparisons. Related: CAPM (Capital Asset Pricing Model), WACC (Weighted Average Cost of Capital), Equity risk premium (ERP / MRP), Fama-French

Cross-sectional momentum

Domain: Trading Plain English: Strategy that buys recent winners and sells recent losers across a universe at a point in time, ranked by past return. Distinguished from Time-series momentum, which trades each asset against its own past. Documented by Jegadeesh-Titman (1993); the original anomaly that spawned the momentum literature. Why it matters: One of the most-replicated factors in equity asset pricing; central to long-short equity playbooks. Related: Time-series momentum, MOM (momentum factor), Fama-French, Carhart four-factor model

CRRA (Constant Relative Risk Aversion)

Domain: Trading / Micro Symbol / formula: u(c) = c^(1−γ) / (1−γ), γ ≠ 1; u(c) = ln c, γ = 1 Plain English: Family of utility functions in which the coefficient of relative risk aversion is the constant γ. The standard preference specification in macro, finance, and consumption-based asset pricing because it nests log utility and produces tractable optimal-portfolio formulas (Merton). Why it matters: Workhorse utility specification; γ ≈ 2–10 in calibrations. Related: Expected utility, Risk aversion, Mertonian portfolio choice

DAI

Domain: Trading (crypto) Plain English: USD-pegged decentralized stablecoin issued by MakerDAO (now Sky), backed by overcollateralized crypto and some real-world assets. Maintains peg via collateralized debt positions and stability fees rather than 1:1 fiat reserves like USDC/USDT. ~$5B supply in mid-2020s. Why it matters: The largest crypto-collateralized stablecoin; reference for "decentralized" stablecoin design. Related: Stablecoin, USDC, Tether, Depeg

Deal spread

Domain: Trading Plain English: In merger arbitrage, the gap between the announced deal price and the target's current stock price, expressed in dollars or percent and annualized. Reflects deal-closing risk: regulatory, financing, market-out. Widens when antitrust scrutiny is high; collapses on certain closing. Why it matters: The P&L engine of [[risk-arb|merger arb]] funds. Related: Risk arb, Merger arbitrage, Special situations

Delta hedge

Domain: Trading (options) Plain English: Trading the underlying in proportion to an option position's delta to neutralize first-order directional risk. Continuous delta hedging is the conceptual backbone of Black-Scholes replication. In practice, hedges are discrete and incur gamma-related slippage. Why it matters: Standard risk-neutralization for option market makers and structured-product books. Related: Greeks (options Greeks), Delta, Gamma, Black-Scholes-Merton formula

Deposit insurance

Domain: Trading / Macro Plain English: Government guarantee covering depositor balances up to a limit ($250k FDIC in the U.S., €100k in the EU, £85k in the UK). Eliminates classic depositor runs on covered balances but introduces moral hazard for banks. SVB (March 2023) tested limits and prompted ad-hoc DIF support for uninsured deposits. Why it matters: Cornerstone of modern bank stability; design tradeoffs central to post-SVB reform debate. Related: FDIC (Federal Deposit Insurance Corporation), Bank run, Moral hazard, SVB-style duration risk

DFAST (Dodd-Frank Act Stress Test)

Domain: Trading / Macro Plain English: Annual Fed-administered stress test under Dodd-Frank for large U.S. banks: a severely adverse macro scenario is projected through bank-specific models to produce stressed losses and capital ratios. Public results inform CCAR (Comprehensive Capital Analysis and Review) capital actions. Methodology has tightened over the 2010s. Why it matters: Primary supervisory diagnostic for large U.S. banks' loss-absorbing capacity. Related: CCAR (Comprehensive Capital Analysis and Review), Stress testing, G-SIB / D-SIB (gsib / dsib)

Drawdown stop

Domain: Trading Plain English: Multi-strategy / pod-shop convention: a portfolio manager is automatically liquidated and capital pulled if cumulative loss exceeds a threshold (typically 5–8%). Enforces firm-wide risk discipline and is a primary explanation for fast unwinds at platform funds (e.g., 2024 quant rotations). Why it matters: Hard-coded risk limit that explains why pod-shop strategies have low individual capacity but compound stably at the firm level. Related: Max drawdown, Pod shop, Multi-strat platforms, Risk officer (hedge fund)

Efficient frontier

Domain: Trading Plain English: Set of portfolios offering the highest expected return for each level of volatility, derived from Markowitz mean-variance optimization. Adding a risk-free asset gives the Capital Allocation Line (CAL); the tangency portfolio is the unique optimal risky portfolio. Why it matters: Defining diagram of MPT; conceptual benchmark for portfolio construction. Related: Markowitz, Mean-variance, CAPM (Capital Asset Pricing Model), Capital Allocation Line (CAL) See also: covered in 05-trading-theory-and-practice.md §Modern portfolio theory.

Equal-risk contribution

Domain: Trading Plain English: Portfolio-construction rule (also called Risk parity) where each asset contributes equally to total portfolio variance — different from equal capital weights. With assets of different vols, ERC tilts toward lower-vol assets and typically requires leverage to reach equity-equivalent risk. Why it matters: Default risk-balanced allocation; intellectual foundation of Bridgewater All Weather and AQR/PanAgora risk parity products. Related: Risk parity, All Weather, Max diversification

Equity long-short

Domain: Trading Plain English: Hedge-fund strategy taking long positions in stocks expected to outperform and shorts in those expected to underperform, typically with net exposure between -20% and +60%. Variants: market-neutral (zero net beta), 130/30, sector-neutral. Largest hedge-fund category by AUM. Why it matters: Workhorse hedge-fund strategy; foundation of fundamental and quant equity investing alike. Related: Market neutral, Risk officer (hedge fund), Long/short, Multi-strat platforms

Exclusion restriction

Domain: Multi (econometrics) Plain English: Identifying assumption in IV: the instrument affects the outcome only through the endogenous variable, not via any other channel. Untestable in general; defended via institutional/narrative argument and falsification tests. Failures are the most common cause of bad IV estimates. Why it matters: The crucial — and contestable — restriction that makes IV identification work. Related: Instrumental variable (IV), 2SLS (Two-stage least squares), LATE (local average treatment effect)

Expected loss

Domain: Trading Symbol / formula: EL = PD × LGD × EAD Plain English: Probability of default × loss given default × exposure at default. The Basel definition of credit-risk expected loss; subtracted from interest income to produce risk-adjusted return on capital. Standard parameters in IFRS 9 / CECL provisioning. Why it matters: The mainstream credit-risk metric for pricing, provisioning, and capital. Related: EAD / PD / LGD / EL / RWA, EAD / PD / LGD / EL / RWA, EAD / PD / LGD / EL / RWA, Unexpected loss

Factor timing

Domain: Trading Plain English: Active overlay that adjusts factor exposures (value, momentum, quality, low-vol) based on valuation spreads, macro conditions, or signal strength. Asness-Ilmanen-Israel-Moskowitz (AQR) argued it works modestly; many practitioners and AQR's own later work conclude timing factors is hard relative to static exposure. Why it matters: Active debate within factor investing; informs whether to "buy and hold" factors or rotate them. Related: Fama-French, Carhart four-factor model, Value spread

Fallen angel

Domain: Trading Plain English: Investment-grade bond that has been downgraded to high yield (BB+ or below). Forced selling by IG-only mandates creates predictable price pressure; fallen-angel ETFs (ANGL) systematically buy these names. Empirical out-performance of fallen angels vs original-issue HY is documented but mixed post-2018. Why it matters: Persistent (if shrinking) anomaly in credit markets; structural feature of investment-grade ratings constraints. Related: Corporate bond, Investment grade, High-yield

Follow-on

Domain: Trading Plain English: Secondary equity offering by a public company after the IPO — issued at a small discount to the current market price. Can be marketed, accelerated bookbuild, or block trade. Distinct from primary IPO and from PIPE (Private Investment in Public Equity) private placements. Why it matters: Standard mechanism for additional capital raise post-IPO; ECM bread and butter. Related: Secondary offering, IPO, PIPE (Private Investment in Public Equity)

Fractional Kelly

Domain: Trading Plain English: Betting (or position-sizing) at some fraction f < 1 of the full Kelly criterion bet, typically f ≈ 0.25–0.5. Sacrifices long-run growth slightly for materially lower drawdowns, accounting for estimation error in edge and odds. Standard in practical trading. Why it matters: The practical implementation of Kelly that survives parameter uncertainty. Related: Kelly criterion, Risk budgeting, Max drawdown

GARCH

Domain: Trading (econometrics) Plain English: Generalized AutoRegressive Conditional Heteroskedasticity (Bollerslev 1986, extending Engle's ARCH). Model in which conditional variance is a linear function of past squared returns and past variances. Captures volatility clustering. EWMA and GARCH(1,1) are the practical defaults. Why it matters: Standard parametric vol-forecasting model; baseline against which more elaborate vol models compete. Related: Volatility (realized, implied), EWMA (Exponentially-Weighted Moving Average), Stochastic volatility

Gates and fees

Domain: Trading Plain English: Tools open-ended funds use to manage redemption surges: redemption gates limit the % of NAV that can leave in a period; redemption fees impose a penalty on early withdrawals. Pioneered for [[mmf-reform|MMFs]] after 2008/2014/2020; standard for hedge funds. Why it matters: Standard fund-level circuit-breaker against [[run-on-a-fund|fund runs]]; contested by investors who view them as expropriation. Related: Run on a fund, MMF reform, Swing pricing

Governance token

Domain: Trading (crypto) Plain English: Crypto-asset whose primary utility is voting on protocol parameters (fee rates, listings, treasury spending). Typically not cash-flow claims, though some protocols share fees with token holders. Examples: UNI, AAVE, MKR. Why it matters: Mechanism by which decentralized protocols try to coordinate upgrades; valuation methodology highly contested. Related: ve-Token (vote-escrowed), DAO (Decentralized Autonomous Organization), Yield farming

Hard-to-borrow

Domain: Trading Plain English: Equity with limited supply available for securities lending — short sellers must pay a high borrow fee, sometimes >5% annualized. Empirically associated with overpricing (Diether-Lee-Werner), but also with concentration risk for shorts. Borrow rates spike around squeezes (GME 2021). Why it matters: Key constraint on the equity short side; the supply curve of stock loan affects mispricing persistence. Related: Securities lending, Short squeeze, Locate, Meme stock

HML (High Minus Low)

Domain: Trading Plain English: Fama-French value factor: long high book-to-market (value) stocks, short low book-to-market (growth) stocks, market-cap-weighted within each. Sourced from Kenneth French's data library. Has underperformed for much of the 2010s/2020s; "death of value" debate. Why it matters: One of the canonical FF factors; recent underperformance has prompted reformulations (e.g., enhanced HML with updated book equity). Related: Fama-French, Value effect, SMB (Small Minus Big), MOM (momentum factor)

HTM vs AFS (Held-to-Maturity vs Available-for-Sale)

Domain: Trading Plain English: U.S. GAAP accounting categories for bank investment securities. AFS marked to market through OCI (other comprehensive income); HTM held at amortized cost with no MTM hit. SVB classified too much in HTM, hiding unrealized losses that became catastrophic when deposits fled (March 2023). Why it matters: Central accounting issue in SVB-style duration risk; ongoing debate about whether AOCI should flow through regulatory capital. Related: SVB-style duration risk, AOCI (Accumulated Other Comprehensive Income), Duration (Macaulay / modified)

ICAPM (Intertemporal CAPM)

Domain: Trading Plain English: Merton (1973) generalization of CAPM to multiple periods: investors care about both current return and how their wealth covaries with future investment opportunities. Generates additional risk factors beyond the market — e.g., factors tracking state variables for the investment opportunity set. Why it matters: Theoretical justification for multifactor pricing (Fama-French) beyond statistical fitting. Related: CAPM (Capital Asset Pricing Model), Fama-French, Mertonian portfolio choice

Initial margin

Domain: Trading Plain English: Collateral posted at trade inception to cover potential losses over a margin period of risk. For cleared derivatives, set by the CCP's risk model (SPAN or VaR). For uncleared, post-2017 BCBS-IOSCO rules require bilateral exchange via segregated accounts. Why it matters: First line of defense in mutualized derivatives risk; pro-cyclical when vol spikes (March 2020). Related: Variation margin, CCP (Central Counterparty), SPAN (Standard Portfolio Analysis of Risk), Uncleared margin rules (UMR)

Interest rate parity

Domain: Trading / Macro Symbol / formula: F / S = (1 + r_d) / (1 + r_f) Plain English: No-arbitrage relationship in FX: forward exchange rate = spot × ratio of interest rates. Holds tightly for covered IRP (when FX swaps are used to hedge). Uncovered IRP — that expected spot equals the forward — is consistently violated, generating the Carry trade (FX) premium. Why it matters: Foundation of FX pricing; the carry trade exists precisely because uncovered IRP fails. Related: Carry trade (FX), CIP deviation, FX swap

IS algorithm (Implementation Shortfall)

Domain: Trading Plain English: Execution algorithm that minimizes the difference between the decision price (arrival or close before parent order) and the final average fill price. Almgren-Chriss framework is the analytical core; practitioners use risk-aversion parameters to balance market impact and timing risk. Why it matters: Default institutional execution algo; the implementation of modern execution theory. Related: Almgren-Chriss model, TWAP / VWAP, TWAP / VWAP, Market impact

L2 (Layer 2)

Domain: Trading (crypto) Plain English: Blockchain scaling tier built on top of an L1 base chain (Ethereum). Optimistic rollups (Arbitrum, Optimism, Base) and ZK rollups (zkSync, Starknet, Scroll) batch transactions off-chain and post compressed proofs to L1. Drives Ethereum's Rollup-centric roadmap. Why it matters: Where the bulk of Ethereum activity now happens; central to scaling and fee economics. Related: Optimistic rollup, zk-rollup, Rollup-centric roadmap, Blob (EIP-4844)

LCR (Liquidity Coverage Ratio)

Domain: Trading / Macro Symbol / formula: LCR = HQLA / Net cash outflows over 30 days ≥ 100% Plain English: Basel III liquidity rule: banks must hold High-Quality Liquid Assets (Level 1: cash, reserves, Treasuries; Level 2: select corporates) covering 30 days of stressed net outflows. Made operational in U.S. via Reg WW. Why it matters: Primary regulatory liquidity buffer; constrains bank funding mix and shapes Treasury and reserve demand. Related: NSFR (Net Stable Funding Ratio), Basel III / IV, HQLA (High Quality Liquid Assets)

Lit vs dark venue

Domain: Trading Plain English: Lit venues (NYSE, Nasdaq, Cboe) display pre-trade quotes; dark venues (most ATSs, internalizers) do not. Dark execution avoids signaling but at the cost of price transparency. ~40% of U.S. equity volume off-exchange in 2024; SEC has periodically proposed limits. Why it matters: Core market-structure choice driving spread, depth, and best-execution analyses. Related: Dark pool, ATS (Alternative Trading System), Internalization, Order Protection Rule

Local vol

Domain: Trading (options) Plain English: Dupire's framework (1994): a deterministic volatility function σ(S, t) that exactly reproduces market option prices across strikes and maturities at one point in time. Useful for pricing path-dependent exotics consistently with the vanilla surface. Distinct from Stochastic volatility (random vol). Why it matters: Foundation of options-desk exotic pricing; consistent with no-arbitrage by construction. Related: Stochastic volatility, Implied volatility (IV), Vol skew

Locate

Domain: Trading Plain English: A broker's confirmation that shares are available to borrow for a short sale, required by SEC Rule 203 of Reg SHO before short-selling US equities. Locate failures became politically salient during the 2021 GME episode and SEC reform attempts. Why it matters: Procedural lynchpin of legal short-selling; one of the main bottlenecks shorts face in Hard-to-borrow names. Related: Securities lending, Reg SHO, Hard-to-borrow

Lopez de Prado

Domain: Trading (ML) Plain English: Marcos Lopez de Prado: practitioner-academic (formerly AQR, True Positive, Cornell) and author of Advances in Financial Machine Learning (2018) and Machine Learning for Asset Managers (2020). His Triple-barrier method, Meta-labeling, Purged k-fold CV, and Deflated Sharpe ratio (Bailey-López de Prado) are now standard in quant ML workflows. Why it matters: Defined the methodological best-practice toolkit for applying ML to financial data while controlling for false discovery. Related: Triple-barrier method, Meta-labeling, Purged k-fold CV, Deflated Sharpe ratio (Bailey-López de Prado) See also: covered in 05-trading-theory-and-practice.md §Machine learning workflow.

Low-vol

Domain: Trading Plain English: Anomaly in which low-volatility stocks earn higher risk-adjusted returns than high-volatility stocks — empirically robust (Frazzini-Pedersen "betting against beta," Ang-Hodrick-Xing-Zhang). Possible explanations: leverage constraints, benchmark-tracking, lottery preferences. Why it matters: Among the most-replicated equity anomalies; basis of "low-volatility ETF" category. Related: BAB (Betting Against Beta), Lottery preferences, Factor zoo

Managed futures

Domain: Trading Plain English: Synonym for [[cta|CTAs]] — pooled vehicles trading futures and forwards, typically systematic trend-following. Long-vol return profile (positive in tail events; negative in choppy markets). Historically strong diversifier in 60/40-style portfolios. Why it matters: One of the few systematic strategies with positive expected return that also rallies in equity drawdowns (notably 2022). Related: CTA (Commodity Trading Advisor / managed futures), Trend following, Time-series momentum

Markowitz

Domain: Trading Plain English: Harry Markowitz; his 1952 Journal of Finance paper Portfolio Selection introduced mean-variance optimization, the Efficient frontier, and the analytical insight that diversification reduces portfolio variance below the average of asset variances. Shared 1990 Nobel. Why it matters: Single most influential framework in portfolio construction; basis of all subsequent modern portfolio theory. Related: Mean-variance, Efficient frontier, MPT (Modern Portfolio Theory) See also: covered in 05-trading-theory-and-practice.md §Modern portfolio theory.

Market neutral

Domain: Trading Plain English: Strategy targeting zero (or very low) market beta — long and short positions sized so that aggregate beta is near zero. Pure stock-picking exposure; popular in factor / stat-arb funds and pod-shop sleeves. Why it matters: Removes systematic risk so returns reflect manager skill (or factor exposure) rather than market direction. Related: Equity long-short, Long/short, Beta

Max diversification

Domain: Trading Plain English: Choueifaty-Coignard (2008): portfolio weights chosen to maximize the diversification ratio = weighted average of asset vols / portfolio vol. Closely related to but distinct from risk parity; produces concentrated portfolios in low-correlation assets. Why it matters: One of several "risk-aware" alternatives to mean-variance that try to be less estimation-error sensitive. Related: Equal-risk contribution, Risk parity, Markowitz

Max drawdown

Domain: Trading Plain English: Largest peak-to-trough percentage decline in cumulative returns over a sample. Standard tail-risk measure for backtests and live track records; complements Sharpe and Sortino. Calmar ratio = annualized return / max drawdown. Why it matters: Investors care about drawdowns viscerally; many allocations are size-constrained by drawdown caps. Related: Drawdown stop, Calmar ratio, Ulcer index

MBS RV (Mortgage-Backed Securities Relative Value)

Domain: Trading Plain English: Fixed-income strategy taking long-short positions in agency MBS coupons, durations, or vs Treasuries based on Prepayment risk and OAS spreads. Major players: Pimco, BlackRock, Bridgewater (smaller), specialist funds. Blew up notably in 2007–08 and 2013 taper tantrum. Why it matters: Largest single sub-strategy in fixed-income RV; sensitive to prepayment models and mortgage convexity. Related: Prepayment risk, OAS (Option-Adjusted Spread), MBS (Mortgage-Backed Security), Fixed-income arbitrage

Mean reversion

Domain: Trading Plain English: Tendency of a series to revert toward a long-run mean. In trading, mean-reversion strategies bet on retracements (short-term equity pairs, treasury basis snap-backs, FX vol mean reversion). Contrast with Trend following / [[mom|momentum]]. Why it matters: Foundation of stat-arb, pairs trading, and many short-horizon execution algos. Related: Stat arb (statistical arbitrage), Pairs trading, Momentum (factor)

Mean-variance

Domain: Trading Plain English: Markowitz's framework: rank portfolios by expected return (mean) and variance, prefer high-mean-low-variance. Generates the Efficient frontier. Inputs are the expected-return vector, covariance matrix, and risk-aversion coefficient; outputs are weights. Why it matters: Conceptual backbone of portfolio construction even where modifications (risk parity, Black-Litterman) are applied. Related: Markowitz, Efficient frontier, MPT (Modern Portfolio Theory), Black-Litterman model

Meme stock

Domain: Trading Plain English: Equity with retail-driven, social-media-amplified buying that detaches price from fundamentals. GME (January 2021) is the prototype; AMC, BBBY, and parts of the 2024 retail surge are variants. Often involves Gamma squeeze dynamics and elevated short interest. Why it matters: New market-structure category; forced reconsideration of retail-flow modeling and short-selling fragility. Related: GME-style dynamics, Gamma squeeze, Short squeeze

Meta-labeling

Domain: Trading (ML) Plain English: Lopez de Prado's two-stage ML approach: a primary model decides direction (long/short); a secondary "meta" classifier decides whether to take the trade and at what size. Improves precision over a single binary classifier, especially with imbalanced classes. Why it matters: Modern standard for combining alpha signals with risk filters in ML-driven strategies. Related: Lopez de Prado, Triple-barrier method, Purged k-fold CV

Mid (price)

Domain: Trading Plain English: The midpoint of bid and ask quotes — (best bid + best ask) / 2. The standard benchmark price for marking positions, attributing P&L, and decomposing execution into spread costs and impact. Why it matters: The reference price for nearly all execution analytics and mark-to-market. Related: Bid-ask spread, NBBO (National Best Bid and Offer), Adverse selection (market making)

MMF reform

Domain: Trading / Macro Plain English: 2014 and 2023 SEC amendments to Rule 2a-7 governing money market funds, in response to runs (2008 Reserve Primary, 2020 prime MMF stress). Floating NAV for institutional prime, mandatory liquidity fees, and (2023) higher liquidity buffers. Drove flows from prime to government MMFs. Why it matters: Major NBFI-stability reform; reshaped the short-term funding landscape. Related: Gates and fees, Run on a fund, Swing pricing

MOM (momentum factor)

Domain: Trading Plain English: Carhart's "Up Minus Down" / "Momentum" factor: long top-decile past-12-month-return stocks (skip most recent month), short bottom-decile. Constructed by Kenneth French and posted on his library. The most reliably-replicated equity-anomaly factor. Why it matters: Persistent positive premium in equities, FX, and commodities; central to multi-asset systematic strategies. Related: Carhart four-factor model, Cross-sectional momentum, Time-series momentum

Multi-strat platforms

Domain: Trading Plain English: Hedge-fund firms (Citadel, Millennium, Point72, Balyasny, ExodusPoint, BAM, Schonfeld) running many PMs ("pods") across strategies on a centralized risk/operations platform. Pass-through fee model with high investor share class; concentrated in NYC, London, HK. Why it matters: Dominant hedge-fund growth model post-2015; massive AUM and concentrated capacity in factor and equity-stat-arb space. Related: Pod shop, Drawdown stop, Risk officer (hedge fund)

Notional

Domain: Trading Plain English: Face value of a derivative contract used to scale cash flows; itself never exchanged in most contracts (swaps, futures). A $100m notional 5y swap exchanges fixed-floating coupons computed on $100m, but principal is not paid. Why it matters: Standard scaling number; gross notional can dramatically exceed net economic exposure. Related: VAR-econometrics (Vector Autoregression), Gross notional, Mark-to-market (MTM)

Novation

Domain: Trading Plain English: Legal substitution of one party for another in a contract — in CCP clearing, the bilateral trade is novated to two separate trades with the CCP as counterparty. Also used in bilateral assignment of OTC derivatives between dealers. Why it matters: The legal mechanism enabling CCP risk mutualization; central in post-2008 derivatives reform. Related: CCP (Central Counterparty), Clearing, Assignment (treatment)

OATs OIS (spread)

Domain: Trading Plain English: Spread between French government bond yields (OATs) and the Eurosystem OIS curve — a sovereign-credit-risk proxy. Spiked to ~80 bp in mid-2024 around the French snap election, having traded in a 30–45 bp range. Eurozone analogue of swap spreads in USD. Why it matters: Indicator of perceived French sovereign-risk and Euro-area fragmentation risk. Related: Swap spread, Sovereign spread, Bund-Bono spread

Optimistic rollup

Domain: Trading (crypto) Plain English: L2 scaling design in which transactions are executed off-chain and posted to L1 with a brief challenge window (typically 7 days) during which any actor can submit a fraud proof. Examples: Arbitrum, Optimism, Base. Cheaper than ZK rollups today but with delayed finality. Why it matters: Most-deployed L2 architecture in 2024–25; carries the majority of Ethereum-ecosystem activity. Related: L2 (Layer 2), zk-rollup, Rollup-centric roadmap, Fraud-proof

Oracle

Domain: Trading (crypto) Plain English: Service that posts off-chain data (prices, weather, sports results) on-chain for smart contracts to consume. Chainlink dominates the price-oracle market for DeFi. Oracle manipulation has been the leading cause of large DeFi exploits. Why it matters: Single biggest source of DeFi smart-contract risk; centralization of oracles is a structural concern. Related: Chainlink, DeFi (Decentralized Finance), Flash-loan attack

Order Protection Rule

Domain: Trading Plain English: Reg NMS Rule 611 ("trade-through rule"): a market center cannot execute at a price inferior to a protected (top-of-book, automated) quote on another exchange. Forces routing across venues; basis of NBBO concept. Periodically debated; SEC has proposed modifications. Why it matters: Single most consequential rule in U.S. equity market structure post-2007. Related: Reg NMS, NBBO (National Best Bid and Offer), Lit vs dark venue

Parallel trends

Domain: Multi (econometrics) Plain English: Identifying assumption in diff-in-diff: in the absence of treatment, the treated and control groups would have evolved in parallel. Testable indirectly via pre-treatment trends; failure is the main threat to DiD identification. New estimators handle violations and staggered timing. Why it matters: Validates the entire diff-in-diff family of estimates; pre-trend graphs are now standard robustness. Related: Diff-in-diff, Two-way fixed effects (TWFE), Event study

PIPE (Private Investment in Public Equity)

Domain: Trading Plain English: Private placement of equity (or convertible securities) by a public company at a discount to the market, typically to a small set of accredited investors. Often used for distressed situations, SPAC mergers, or financing growth without a fully-marketed offering. Why it matters: Flexible alternative to a follow-on; large during the 2020–21 SPAC wave and in distressed financings. Related: Follow-on, Secondary offering, SPAC (Special Purpose Acquisition Company)

Premium vs NAV

Domain: Trading Plain English: For closed-end funds or ETFs: the percent difference between the market price and the per-share net asset value. ETFs trade tight to NAV via arbitrage; CEFs can trade at sustained 5–20% discounts or premiums. Premium widens in popular themes (e.g., GBTC pre-conversion premium / discount). Why it matters: Direct measure of arbitrage friction and investor flow imbalance; relevant in CEF and crypto-trust valuation. Related: NAV (Net Asset Value), Closed-end fund (CEF), Creation / redemption (ETF), Arbitrage mechanism

Prepayment risk

Domain: Trading Plain English: Risk that mortgage borrowers prepay their loans (refinance or sell), shortening the duration of [[mbs-rv|MBS]] when rates fall. Negative convexity for the MBS investor — they get cash back when reinvestment yields are lowest. Modeled by prepayment functions like PSA and OAS analytics. Why it matters: Defines the unique convexity profile of agency MBS and the reason for OAS-based pricing. Related: OAS (Option-Adjusted Spread), Negative convexity, MBS RV (Mortgage-Backed Securities Relative Value)

Priority fee (Ethereum)

Domain: Trading (crypto) Plain English: The "tip" portion of an Ethereum transaction fee under EIP-1559 — paid directly to the block proposer, on top of the burned base fee. Searchers add high priority fees to be included quickly; the priority fee market is one of the main MEV pricing surfaces. Why it matters: Direct economic incentive in Ethereum's block-building market; relevant for searcher/builder/proposer revenue split. Related: Base fee (EIP-1559), MEV (Maximal Extractable Value), MEV-Boost

Purged k-fold CV

Domain: Trading (ML) Plain English: Lopez de Prado's cross-validation scheme for time-series ML in finance: training and test folds are purged of observations whose labels overlap in time, preventing leakage. Combined with an embargo around fold boundaries. Mandatory for any ML model exposed to financial time-series. Why it matters: The most-cited methodological correction in financial ML; ordinary k-fold CV systematically over-estimates out-of-sample Sharpe. Related: Lopez de Prado, Triple-barrier method, Meta-labeling, Deflated Sharpe ratio (Bailey-López de Prado)

Q-factor model

Domain: Trading Plain English: Hou-Xue-Zhang (2015) 4-factor model: market, size, investment, and profitability — derived from q-theory of investment. Often outperforms Fama-French 5-factor in head-to-head tests. Why it matters: Leading modern competitor to Fama-French; theoretically grounded rather than empirically motivated. Related: Hou-Xue-Zhang (q-factor model), Fama-French, Factor zoo

Quant quake

Domain: Trading Plain English: August 2007 episode in which many quantitative equity long-short strategies suffered simultaneous large losses (~3 standard deviations) over a few days, despite low market moves. Driven by deleveraging of a few large books spilling into crowded factor exposures. Repeated in milder forms (2018, 2019, 2024). Why it matters: Defining moment for the quant industry; showed factor-crowding risk and motivated risk-of-ruin discipline. Related: Crowding, Factor zoo, Drawdown stop

Queue position

Domain: Trading Plain English: An order's position in the price-time-priority queue at a given price level — how many shares ahead must trade before yours fills at that price. Critical for market makers; HFT firms compete to be early in queues for stable, popular levels. Why it matters: Determinant of fill probability and adverse-selection cost at a given limit price. Related: Price-time priority, Limit order book, Adverse selection (market making)