What is MEV?
Last reviewed 2026-05-03
Entity coverage: 5 protocols, 0 tokens, 0 chains reference this concept.
Term coined in: Flash Boys 2.0: Frontrunning, Transaction Reordering, and Consensus Instability in Decentralized Exchanges (2019) by Daian, Goldfeder, Kell, Juels et al.
Cite / Read deeper: DeFi Intel mev deep-dive
MEV is the value a block proposer (or builder) can extract by ordering, including, or censoring transactions. Originally "miner extractable value." Sources: arbitrage, sandwich attacks, liquidations, JIT liquidity, NFT sniping. Annualized at $500M-$1B+ on Ethereum.
MEV-Boost (Flashbots) decouples builders from validators: builders compete to construct the most profitable block, validators rent block space.
How it works
Every transaction broadcast to a public mempool is visible before it is confirmed. Searchers run bots that scan this queue and on-chain state for profitable situations: a DEX price gap to arbitrage, an undercollateralized loan to liquidate, or a large swap to sandwich (buy just before it, sell just after, pocketing the price impact).
To capture an opportunity, a searcher constructs a bundle — its own transactions placed in an exact order relative to the target transaction — and bids for inclusion, either through priority fees or by submitting the bundle privately to block builders.
On Ethereum under proposer-builder separation (MEV-Boost), builders assemble candidate blocks from these bundles plus regular transactions, competing to build the most valuable block. Relays pass sealed blocks to the validator scheduled to propose, which typically signs whichever header pays the most, so much of the extracted value is bid back to the proposer. Users mitigate MEV by setting tight slippage, routing through private RPCs that skip the public mempool, or trading via batch auctions and MEV-protected order flow.
Why it matters
MEV represents a tax on users — billions of dollars per year — and a centralizing force on validators (who otherwise rent block-building to a small cartel). Mitigating MEV is core to Ethereum credibility.
Real-world examples
Sandwich attacks (Wintermute searcher trades), arbitrage backruns, JIT liquidity on Uniswap v3, NFT mint sniping, liquidations on Aave.
Related terms
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MEV deep-dive Browse GlossaryFrequently asked questions
What is MEV in crypto?
MEV is the value a block proposer (or builder) can extract by ordering, including, or censoring transactions, originally called 'miner extractable value.'
What are the main sources of MEV?
Sources include arbitrage, sandwich attacks, liquidations, JIT liquidity, and NFT sniping.
How does MEV-Boost work on Ethereum?
MEV-Boost decouples builders from validators: builders compete to construct the most profitable block, and validators rent block space, typically signing whichever header pays the most.