Uniswap Labs has launched StablePair Hook, a Uniswap v4 tool that sets liquidity-provider fees dynamically for two stable-pair pools on Ethereum rather than charging one constant rate.

The launch covers USDC/USDT and USDC/USDG. For liquidity providers, the material change comes when a pool moves away from its expected rate: corrective trades outside a configured price band are auctioned through a fee that falls each block, allowing the pool to retain part of the arbitrage opportunity as fee revenue.

A fixed-fee stable-pair pool charges the same percentage when its assets are near parity and when they have moved apart. Uniswap’s stated tradeoff is that a low fee leaves more of the corrective spread to arbitrageurs, while a high fee can make the pool’s quotes uncompetitive.

Fees Follow Price and Trade Direction

StablePair configures each pool with a reference rate and a narrow band around it. The hook sets the LP fee from the pool price, its distance from the reference rate and the direction of the proposed trade.

Inside the band, the fee changes to maintain consistent pre-price-impact buy and sell quotes. At the reference rate, both directions pay the configured band width. Near an edge, the fee for a trade moving toward that edge falls toward zero, while the fee in the opposite direction rises toward roughly twice the band width.

Outside the band, a trade pushing the pool farther from the reference rate pays no fee because it does not extract the existing mispricing. A corrective trade 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 at execution.

The mechanism does not eliminate price impact. The fee is independent of swap size, and Uniswap’s documentation says a large trade can still move along the pool’s pricing curve and receive a worse average price than a smaller trade.

Uniswap said stablecoin-to-stablecoin swaps on its protocol totaled $43.4 billion in the second quarter. StablePair’s launch is limited to the two Ethereum pools, which only Uniswap Labs can create against the hook. Pool parameters and fee logic can be changed through Uniswap governance without requiring liquidity to migrate to a new pool.