Crypto

Automated market maker

Also calledAMM · AMM

An automated market maker is a decentralized trading mechanism that prices swaps with a mathematical formula instead of a continuous order book. The pool’s reserves, not a human dealer, determine the quoted exchange rate, although arbitrage and external markets keep prices aligned.

What Automated market maker means

An AMM lets users trade directly against a liquidity pool. When someone buys one token, the pool’s balance changes and the formula adjusts the price. Common AMM designs use constant-product or similar curves, which makes trade size matter: larger trades usually move the price more than smaller ones.

AMMs make onchain trading possible without a central matching engine. That changes execution behavior: traders may face slippage, liquidity providers may earn fees, and prices can move as the pool is rebalanced by arbitrage. Understanding the formula matters because it affects execution quality and risk.

In a simplified constant-product AMM, a pool with 10 ETH and 20,000 USDC implies 2,000 USDC per ETH before fees. If a trader buys ETH, the ETH reserve falls and the implied price rises. The pool does not “know” market price; arbitrage keeps it close to external markets over time.

Common questions

Is an AMM the same as a market maker?+

Not exactly. A traditional market maker is an entity; an AMM is a code-based mechanism that sets prices and executes swaps against pooled liquidity.

Do AMMs always use the same formula?+

No. Many use constant-product style formulas, but some protocols use different curves, fee structures, or concentrated liquidity models.

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01Uniswap v2 Whitepaper02Uniswap Docs — Whitepaper03Ethereum.org — Glossary: automated market maker