What Is MEV?
MEV (Maximal Extractable Value) is the profit that block producers (validators/miners) and specialized "searchers" can extract by manipulating the ordering of transactions within a block. This includes front-running DEX trades, back-running liquidations, and executing arbitrage between protocols — all by controlling transaction sequence.
How MEV Works
On Ethereum, transactions sit in a public mempool before inclusion in a block. MEV searchers monitor this mempool and identify profitable opportunities:
- Front-running — Placing a buy order before a large pending buy, then selling after
- Sandwich attacks — Placing orders before and after a victim's trade to profit from price impact
- Liquidation sniping — Being first to execute undercollateralized loan liquidations
- DEX arbitrage — Exploiting price differences between AMM pools
Why It Matters for Traders
MEV costs DeFi users an estimated $500M+ annually through worse execution prices. Understanding MEV helps traders protect themselves: using private mempools (Flashbots Protect), setting tight slippage tolerances, and routing through MEV-aware aggregators. It's also a tradeable opportunity for sophisticated on-chain operators.