How liquidity pools work
Instead of an order book matching buyers and sellers, AMM-based DEXs use a mathematical formula to price swaps against a shared pool. The most common is Uniswap V2’s constant product: x × y = k, where x and y are the pool’s reserves of each token. Every swap must preserve k (minus the fee), so larger trades against smaller pools push price further.
Depositing into the pool:
- You deposit both tokens in the pool’s current ratio (e.g. 1 ETH + 3,000 USDC).
- You receive LP tokens representing your pool share.
- Every swap that touches the pool pays a fee (typically 0.05-1%) split proportionally among LP token holders.
- You can redeem your LP tokens anytime for your share of the current pool reserves.
Newer AMM designs improve on the basics: Uniswap V3 uses concentrated liquidity where LPs pick a price range; Curve uses formulas optimized for stable-to-stable swaps; Balancer allows weighted multi-token pools.
Why LPs matter
Liquidity pools are the reason DeFi works without centralized market makers. Every major protocol — DEXs, perp venues, lending, synthetics — bootstraps with LPs who provide the asset-for-asset depth that trades execute against. Yield-farming programs pay LPs additional token emissions on top of swap fees, which is how projects incentivize deep liquidity in new markets.
Risks and considerations
Impermanent loss is the core risk: if the price ratio of the pool’s tokens changes, LPs end up with fewer of the appreciating asset and more of the depreciating one than if they’d just held. For ETH/USDC during a strong ETH rally, an LP can underperform simply holding by 5-15% depending on the move size.
Other risks: smart-contract bugs (pool exploits have drained millions), rug pulls on low-liquidity tokens where the project creator removes the pool after farming emissions, MEV sandwich attacks on swaps through the pool, and oracle manipulation for LPs that feed price data into lending protocols. Before depositing, check the pool’s TVL, age, audit status, and which DEX aggregators actually route through it — pools nobody trades against generate no fee income and carry all the risk.