Crypto glossary
MEV (maximal extractable value)
MEV, or maximal extractable value, is the profit that can be captured by deciding which transactions go into a block and in what order they appear.
Whoever builds a block decides the order of its transactions. By watching pending transactions in the mempool, specialized bots called searchers spot opportunities such as arbitrage between exchanges, liquidations on lending protocols and sandwich attacks, then pay block builders and validators to place their own transactions in a profitable position.
The term originally stood for miner extractable value and was renamed after Ethereum moved to proof of stake. Today most Ethereum blocks are produced through MEV-Boost, which separates block building from block proposing: builders compete to assemble the most valuable block and validators pick the highest bid.
Some MEV, like arbitrage, keeps prices aligned across markets. Sandwich attacks, by contrast, directly cost ordinary traders through worse execution. Private transaction relays, MEV-protected RPC endpoints and tight slippage settings are common defenses.
Example
A bot sees a large buy order for a token on Uniswap, buys just before it to push the price up and sells right after it, pocketing the difference: a sandwich attack.
Related terms
Latest articles on MEV
- THORChain’s Swap Queue Blocks Sandwich Attacks and Cuts MEV Costs for Traders
- MEV Analysis in DeFi: Extraction Mechanisms and Financial Losses for Retail Users
- JaredFromSubway Offers Bounty after MEV Exploit
- The Hidden Costs of “Decentralized Freedom”: Slippage, MEV, and the True Price of On-Chain Trading
- Flare Unveils Plan to Shift MEV Into the Base Layer and Slash Inflation to 3%
