What Is MEV in Crypto? Maximal Extractable Value

MEV (maximal extractable value) is the profit that can be captured by choosing which transactions go into a block and in what order. Whoever controls or influences ordering, or the bots that bid for it, can capture value from arbitrage, liquidations and other users' trades. For ordinary DeFi users, MEV mostly shows up as worse execution on swaps.

MEV definition

MEV stands for maximal extractable value. The term was coined as "miner extractable value" in the 2019 research paper Flash Boys 2.0 by Phil Daian and colleagues, which studied bots front-running trades on Ethereum DEXs. Once Ethereum moved to proof of stake in 2022 and validators replaced miners, "maximal" became the standard word.

The core idea: a block producer is not obliged to process transactions in the order they arrived. It can include, exclude or reorder them. Any opportunity that exists only because of a specific ordering is MEV.

Some MEV is broadly useful. Arbitrage keeps prices aligned across exchanges, and liquidation bots keep lending markets solvent. Other MEV, like sandwiching, is a direct transfer from ordinary users to bots.

How MEV works

1. Observe. Searchers (specialised bots) watch pending transactions and on-chain state for profitable opportunities.
2. Construct. They build a transaction, or a bundle of several, that captures the opportunity, such as buying before a large swap and selling after it.
3. Bid for ordering. They pay for placement through high fees or, on Ethereum, by sending bundles to block builders, who then compete to have validators include their blocks.
4. Extract. If the bundle lands in the intended order, the searcher keeps the profit, and part of it flows to builders and validators.

Common MEV strategies include DEX arbitrage, liquidations, back-running (trading straight after a large swap to capture the price it moved) and sandwich attacks. How much of this is possible varies by chain. Ethereum's public mempool makes pending trades very visible, while chains such as Sui and MultiversX order and reveal transactions differently, so the opportunities and defences differ too, but no chain where someone decides ordering is completely free of MEV.

MEV example

A hypothetical arbitrage. Say ETH trades at 3,000 USDC on DEX A and 3,030 USDC on DEX B after a large buy on B.

• A searcher buys 10 ETH on DEX A for about 30,000 USDC.
• In the same bundle, it sells the 10 ETH on DEX B for about 30,300 USDC.
• Gross profit: about 300 USDC, before price impact, swap fees and the fee paid to win the ordering.

Many bots spot the same opportunity, so they bid against each other for priority. Competition tends to hand most of that 300 USDC to the block producer as fees, leaving the winning searcher a thin margin. That auction for ordering is MEV in miniature.

Why MEV matters

• Hidden trading cost. If your swap is sandwiched, you receive less than you would have, and the loss never shows as a separate fee. A tight slippage tolerance limits how much can be taken.
• Protocol design. Protocols that leak value to MEV bots, through predictable liquidations or rebalances, effectively pay that value away from their users. Asking how a protocol handles this is part of checking whether a DeFi protocol is safe.
• Perpetual and order-book DEXs. Venues with on-chain order books face their own ordering games, such as racing to cancel stale quotes; our perp DEX explainer covers how they differ from AMMs.
• Chain choice. MEV exposure depends on how a chain orders transactions. Where liquidity is deep and execution is fast, as compared in our Sui DEX comparison, ordinary-size trades leave less room to extract.

Related terms

• Sandwich attack — the most user-hostile form of MEV.
• Slippage — the price gap your tolerance setting allows MEV bots to use.
• Flash loan — borrowed capital that lets searchers run arbitrage without their own funds.
• Gas fees — the fees searchers bid up to win transaction ordering.
• DEX (decentralized exchange) — where most MEV opportunities originate.

Learn more on the JewelSwap blog

• Sui DEX comparison 2026 — liquidity depth and execution across the major Sui exchanges.
• How to check a DeFi protocol is safe — a practical checklist that includes oracle and MEV exposure.
• What is a perp DEX? — how perpetual exchanges work and where ordering matters.

Frequently asked questions

What does MEV stand for in crypto?

MEV stands for maximal extractable value. It was originally called miner extractable value, from the 2019 Flash Boys 2.0 paper, and was renamed after Ethereum's move to proof of stake because validators, not miners, now order blocks.

Is MEV bad?

Not all of it. Arbitrage and liquidations help keep prices accurate and lending markets solvent. Sandwich attacks and other front-running, however, take value directly from users and are widely seen as harmful.

MEV vs front-running: what is the difference?

Front-running is one MEV strategy: placing a transaction ahead of a known pending one to profit from it. MEV is the broader category covering all value from transaction ordering, including arbitrage, back-running and liquidations.

JewelSwap Crypto Glossary · educational, not financial advice. Updated 2 October 2026. Browse the full glossary.