Uniswap Labs has launched StablePair Hook, a Uniswap v4 dynamic-fee mechanism for USDC/USDT and USDC/USDG pools on Ethereum mainnet. Live from September 10, 2026, the tool uses a 1:1 reference rate and a narrow price band to adjust liquidity-provider fees based on a pool's deviation from parity and a swap's direction. Trades that push a pool further from the reference rate pay no liquidity-provider fee, while corrective trades face a Dutch-auction fee that declines with each Ethereum block until executed. Uniswap said its protocol handled $43.4 billion in stablecoin-to-stablecoin swaps during the second quarter of 2026, more than the next three on-chain venues combined. OpenZeppelin found a high-severity transaction-splitting issue in a predecessor of the core fee mechanism, which Uniswap said it fixed by caching the pool price once per block. StablePair remains upgradeable through Uniswap governance without requiring liquidity migration, while pool creation is restricted to Uniswap Labs.