Glossary
Just-in-Time (JIT) Liquidity
A concentrated-liquidity AMM tactic where a sophisticated LP adds tight liquidity around a known incoming swap and removes it immediately after — capturing fees with minimal IL.
JIT liquidity exploits Uniswap v3's concentrated-liquidity model. A searcher observes a large pending swap in the mempool, front- runs it by depositing extremely tight liquidity around the current price, captures most of the swap fee, and removes the liquidity in the next transaction.
The tactic is technically legal MEV — the searcher provides real liquidity to the swap — but it crowds out passive LPs by capturing fees they would otherwise have earned. Uniswap v4 hooks open new designs for blocking or compensating for it.