Uniswap Labs has switched on StablePair Hook, a v4 tool that sets fees for liquidity providers based on pool conditions. The first use covers two stablecoin pools on Ethereum: USDC/USDT and USDC/USDG. Instead of one fixed fee, each pool now adjusts its LP fee as prices move and as trades push in different directions.
How the fee changes
StablePair gives each pool a reference rate and a narrow band around it. The hook reads the pool price, the distance from that reference, and the direction of the proposed trade. Inside the band, fees shift to keep buy and sell quotes roughly balanced before price impact. At the reference rate, both sides pay the configured band width. Near an edge, a trade moving toward that edge sees its fee fall toward zero. A trade moving the other way pays more, roughly twice the band width.
Outside the band, the logic changes. A trade that pushes the pool farther from the reference rate pays no fee. That trade is not extracting existing mispricing, according to Uniswap. A corrective trade, meaning one that helps bring the pool back, faces a fee that starts at the far edge of the band and decays once per block until someone accepts it. The pool collects the fee charged when the trade executes. This auction-like approach lets LPs keep part of the arbitrage opportunity that would otherwise go to arbitrageurs.
Limits and tradeoffs
Fixed-fee stable pools charge the same percentage when assets trade near parity and when they drift apart. Uniswap says that creates a tradeoff. A low fee leaves more corrective spread for arbitrageurs. A high fee can make the pool’s quotes less competitive. StablePair tries to sit between those outcomes, but it does not remove price impact. The fee is independent of swap size. Uniswap’s documentation notes a large trade can still move along the pricing curve and get a worse average price than a smaller trade.
The launch is limited. Only those two Ethereum pools are live, and only Uniswap Labs can create pools against this hook for now. Uniswap said stablecoin-to-stablecoin swaps on its protocol reached $43.4 billion in the second quarter. Pool parameters and fee logic can be changed through Uniswap governance without forcing liquidity to migrate to a new pool. That matters because migration is often a costly step for LPs. For now, the experiment is small, but it could shape how stable-pair pools handle fees if the design holds up in live markets.
