Uniswap v4 Hooks Let Developers Set Rules for Individual Pools

Uniswap v4 lets developers attach external contracts to individual pools, where they can set fee, access and liquidity rules. StablePair pools handled $3.1 billion during their first four weeks.

These programs, called hooks, are optional and attached when a pool is created. A hook can execute on either side of a trade and when users deposit or withdraw liquidity. The selected hook address cannot later be replaced. Pools for the same assets can therefore have different fees or eligibility terms. Uniswap v4 launched in January 2025.

StablePair is designed for assets expected to trade near the same value. It recalculates fees on every swap, though the fee does not necessarily change each time. By Oct. 14, VolatilePair’s Ether-USDC pool was live on Ethereum. Its hook recalculates buying and selling fees separately as prices move, so the charges can respond differently to a trade’s direction and price movement.

Permissioned Pools are designed for tokenized assets with ownership restrictions. Before a trade or liquidity deposit, a hook checks whether the wallet is on the issuer’s approved list. That access check leaves unrelated pools unchanged, while other v4 pools can also restrict access.

Hooks can also change how capital is used between trades. As of June 25, Spark had moved $150 million in stablecoin liquidity to v4 and planned to move it to DualPool. The proposed hook would hold unused assets in yield-bearing vaults and draw on them when trades require pool liquidity. The migration to v4 and the planned DualPool move were separate steps.

The designs also give users different upgrade controls. VolatilePair’s fee logic and settings can be upgraded through Uniswap Governance. StablePair is upgradeable, but permissions encoded in its fixed hook address prevent an upgrade from adding a feature that blocks liquidity withdrawals. Those limits vary by hook.

Upgrade authority, faulty accounting and dynamic fees can affect trades or liquidity. Because pools can use different rules for the same assets, traders and liquidity providers may encounter different fees, access checks and capital arrangements. The permissions attached to each hook are part of the pool’s terms.