Technical Definition

JIT Liquidity

JIT Liquidity (Just-In-Time) JIT liquidity is a strategy on concentrated-liquidity AMMs where a sophisticated LP detects an incoming large swap in the mempool, deposits a massive, tightly-ranged position immediately before the swap executes, captures most of the trading fee, and withdraws the position in the next block.

By Crypto University Editorial
MEVAMMSniping Bot

Key Insight

JIT is a form of MEV that benefits the swapping trader (tighter execution price) but extracts fees from passive LPs (who would otherwise have earned them). Traders should understand JIT both as an opportunity for size execution and as a reason passive LP yields are lower than headline numbers suggest.

Common Misconceptions

Estimating LP returns from historical fees without adjusting for JIT extraction.

Submitting large trades without using private mempools, allowing JIT bots a clean view.

Trying to compete with professional JIT bots without optimized infrastructure.

Detailed Explanation

How It Works: A bot monitors pending transactions. When a large swap appears, the bot front-runs it by adding concentrated liquidity exactly at the current price tick, then back-runs by removing the position immediately after the swap. The JIT LP earns the bulk of the trade's fee for holding capital for one block.

FAQs:

  • Is JIT bad for traders? It can improve execution for the trader being JITed; it hurts passive LPs.

  • Can I avoid being seen by JIT bots? Using private order flow services (e.g., Flashbots Protect) helps.

In Practice

A whale submits a $5M swap on Uniswap v3. A JIT bot supplies $4M of liquidity in the same block, earns most of the ~$1,500 fee, and withdraws — leaving passive LPs with crumbs.

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