Market Making and Liquidity Provision
Market Making and Liquidity Provision is the operational foundation of modern electronic exchanges. Market makers quote simultaneous two-sided prices-bids to buy and asks to sell-earning the fractional bid-ask spread on every matched trade.
However, market making is a game of severe asymmetric information. A market maker faces two mortal risks:
- Inventory Risk: Accumulating an unwanted directional position that moves against them.
- Adverse Selection: Trading against an informed counterparty who knows the price is about to tick up or down before the market maker can cancel their quote.
Core Market Making Topics
This pillar is organised into eleven topic folders (folder-per-topic), each a self-contained hub index.md plus six sub-pages walking from intuition to working formulas and code. Follow them in the order below.
- Limit Order Book Mechanics: The book as the state of the market - limit vs market orders, L2/L3 data, matching engine (price-time priority), queue position, and order flow imbalance.
- Avellaneda–Stoikov & Optimal Quoting: Stochastic control of the two-sided quote - the market-maker’s problem, the HJB solution, reservation price, inventory penalty, and optimal spread.
- Inventory Management & Quote Skewing: The Ho–Stoll dealer model, the inventory risk function, mean-reverting targets, and asymmetric quote skewing.
- Adverse Selection & Glosten–Milgrom: Informed vs noise traders, Bayesian price updating, the sequential-trade model, and spread decomposition.
- Spread Decomposition & the Roll Model: Quoted/effective/realized spreads, return autocovariance, bid-ask bounce, and separating inventory costs from adverse selection.
- Toxic Order Flow & VPIN: PIN/EKOP, the Lee–Ready algorithm, Volume-Synchronized Probability of Toxicity (VPIN), and flash-crash early warnings.
- Market Impact & Depth: The Kyle model and Kyle’s lambda, depth as 1/lambda, temporary vs permanent impact, and the square-root law.
- Liquidity Risk & Asset Pricing: Illiquidity measures (Amihud ILLIQ), liquidity as a priced factor (Pastor–Stambaugh), liquidity risk (Acharya–Pedersen), and crises.
- Market-Maker Economics & Rebates: Market-maker P&L decomposition, maker-taker fees and rebates, competition and the race to zero, and payment for order flow.
- Dealer Banks & OTC Markets: Why OTC markets exist, the Duffie–Garleanu–Pedersen search-and-bargaining model, dealer balance-sheet capacity, and central clearing.
- Crypto & DeFi Market Making: The constant-product AMM as a passive market maker, divergence loss derived from scratch, Uniswap v3 concentrated liquidity as a short-gamma position, MEV/sandwiching - the same adverse selection this pillar formalises, on 24/7 venues.
Reading Path (Zero to Market Maker)
Before this pillar (foundations): read Probability & Measure Theory · Stochastic Calculus · Econometrics & Time Series first - see the Math Foundations hub for the full consumption order.
- Start (the machinery): 1 · Limit Order Book Mechanics → 4 · Adverse Selection & Glosten–Milgrom. You learn what the book is and why a spread exists at all (adverse selection).
- The quoting models: 2 · Avellaneda–Stoikov → 3 · Inventory & Quote Skewing. The two workhorses for how to quote and how to manage the inventory the quotes create.
- Diagnostics: 5 · Spread Decomposition & Roll → 6 · Toxic Flow & VPIN. How to measure the components of the spread and detect when you are being picked off.
- Impact & economics: 7 · Market Impact & Depth → 8 · Liquidity Risk & Asset Pricing → 9 · MM Economics & Rebates. The price-impact view, why liquidity is a priced risk, and whether the business actually makes money after fees.