Profit miners or validators can earn by reordering or including transactions within blocks.
Maximal Extractable Value (MEV) refers to the profit that miners, validators, or bots can capture by reordering, inserting, or excluding transactions within a block. MEV exploits the transparent, public nature of pending blockchain transactions.
MEV has become one of the most influential — and controversial — aspects of modern blockchain economics.
Examples of MEV Strategies
Front-running: Executing a transaction before a large order
Sandwich attacks: Buying before and selling after a user’s trade to capture the price impact
Arbitrage: Exploiting price discrepancies across pools/exchanges
Liquidation bots: Competing to liquidate positions in lending protocols
Back-running: Capturing price movement after major trades
MEV bots compete intensely for opportunities, especially on Ethereum.
Why MEV Exists
Transactions are public in the mempool
Block producers control transaction ordering
Blockchain activity creates profitable inefficiencies
Smart contracts are composable and highly transparent
The Impact of MEV
Positive:
Improves market efficiency
Enables arbitrage and price alignment
Negative:
Causes slippage for regular users
Increases gas bidding wars
Encourages predatory behavior
Centralizes power among sophisticated actors
MEV Mitigation Tools
Flashbots
Private transaction relays
Encrypted mempools
MEV-resistant L2s and sequencing systems
Summary
MEV is the maximum value miners or validators can extract by manipulating transaction ordering. It plays a significant role in DeFi but often affects everyday users.
