Just-in-time (JIT) liquidity is a strategy in which a liquidity provider adds a concentrated-liquidity position immediately before a selected swap and removes it immediately afterward, often within the same block. The position can earn part of that swap’s fee while it is active. JIT is commonly discussed as an MEV strategy, but its effect is not one-sided: extra active liquidity can improve a trader’s execution, while the fee share available to longer-term liquidity providers can fall.
How JIT Liquidity Works
In a concentrated-liquidity pool, only liquidity covering the current price is active for a swap. A JIT provider can place a narrow position around a targeted trade, so that position contributes liquidity during that swap. A typical on-chain pattern is a liquidity mint, the targeted swap, and a liquidity removal in the same block.
To make that sequence work, the provider needs a way to place the transactions in the intended order. Searchers may use public or private order flow and transaction-inclusion infrastructure; the exact route varies. MEV-Boost is one possible part of Ethereum’s block-building environment, not a requirement for every JIT transaction.
Who Gains and Who Bears the Tradeoff?
A JIT position may add depth at the price used by a swap. Research on concentrated-liquidity markets finds that this can reduce price impact for the trader in some cases. The JIT provider may receive a large share of the swap fee if its position supplies much of the active liquidity, but the amount depends on the pool, the position, the trade, competing liquidity, and execution costs.
Longer-term LPs may receive a smaller share of the fee on a trade when JIT liquidity is added. Research also models circumstances where JIT providers crowd out passive liquidity or weaken the incentive to keep liquidity in a pool. These are possible effects, not proof that every JIT trade harms a pool or that every JIT provider earns a profit. Results vary with order flow, price impact, fees, and transaction costs.
JIT Liquidity Is Not a Sandwich Attack
Both strategies rely on transaction ordering, but they use different mechanisms. A classic sandwich attack trades before and after a victim’s swap to move the price against that trader. A JIT provider instead adds liquidity around the swap and earns a portion of its fee. A JIT trade can still involve ordering risk and may not improve execution in every case, but it is not automatically a sandwich or a guaranteed trader benefit.
Social Media Sentiment
A four-year-old r/defi discussion about bots adding and removing liquidity around one swap shows users trying to understand the transaction ordering and why the strategy may focus on larger trades. Replies described the same-block add/swap/remove pattern and pointed to inclusion costs and searcher infrastructure. The thread is old and anecdotal; it illustrates recurring interest in how JIT works, not a current consensus about its fairness or market-wide effects.
Last updated: 2026-10
Related Terms
See Also
- What Is MEV—and Why Every Ethereum Transaction Is a Game
- Why Smart Contract Audits Fail
- How Crypto Bridges Work—and Why They Are a Hack Target
- Swap crypto with ChangeNOW
Sources
- Uniswap v3 Core — Concentrated Liquidity — Defines a position as liquidity bounded to a price range and explains when it is active and earns fees.
- Trotti et al. — Strategic Analysis of Just-In-Time Liquidity Provision — Models JIT liquidity in concentrated-liquidity markets and analyzes possible effects on trader price impact and passive-LP profits.
- Capponi, Jia, and Zhu — The Paradox of Just-in-Time Liquidity in Decentralized Exchanges — Studies conditions where JIT liquidity may crowd out passive providers and reduce overall pool liquidity.