A smart contract holding paired tokens that enables decentralized trading — users deposit assets and earn fees from trades.
A liquidity pool is a smart contract that holds a reserve of two or more tokens, enabling decentralized trading without traditional order books. Liquidity providers (LPs) deposit equal values of paired tokens (e.g., $1,000 of ETH + $1,000 of USDC) into the pool and receive LP tokens representing their share. When traders swap tokens through the pool, they pay a fee (typically 0.3%) that is distributed proportionally to all liquidity providers. This mechanism — pioneered by Uniswap — is the foundation of all AMM-based decentralized exchanges. The deeper a pool's liquidity, the less slippage traders experience on large orders. However, LPs face impermanent loss risk: if the price ratio between the paired tokens changes significantly, LPs may have been better off simply holding the tokens rather than providing liquidity. Concentrated liquidity (Uniswap v3) lets LPs focus capital within specific price ranges for higher capital efficiency.
Liquidity pools are smart contracts holding pairs of tokens that enable decentralized trading through AMMs. When you add tokens to a pool (becoming a Liquidity Provider or LP), you earn a share of trading fees proportional to your contribution. Pools follow mathematical formulas — most commonly x*y=k — that automatically adjust prices based on supply and demand. The major pools on Uniswap, Curve, and Balancer hold billions in combined liquidity. LPs earn from swap fees (typically 0.05-1% per trade) but face impermanent loss risk when token prices diverge. Pool selection significantly impacts returns: high-volume pools with correlated assets (stablecoin pairs, ETH/stETH) offer the best risk-adjusted yields. Fee tiers let LPs choose between wider availability (lower fee, more volume) and higher per-trade income (higher fee, less volume). Concentrated liquidity (Uniswap v3) allows LPs to provide liquidity within specific price ranges for dramatically higher capital efficiency.
A liquidity provider deposits 1 ETH ($3,000) and 3,000 USDC into a Uniswap ETH/USDC pool. Over a month, the pool processes $50M in trades, and the LP earns their proportional share of 0.3% swap fees — roughly $150 on their $6,000 position (30% annualized). However, if ETH's price moves 20%, impermanent loss could reduce or eliminate this gain.
Returns vary enormously: stable pairs might yield 2-10% APY with minimal impermanent loss, while volatile pairs could yield 20-100%+ but with significant IL risk. Total return = trading fees earned minus impermanent loss. High-volume, low-volatility pools generally offer the best risk-adjusted returns for passive LPs.