Maximal extractable value: what it is and why it matters
Maximal extractable value is the extra profit from ordering transactions in a block. Searchers, builders and validators usually compete for that profit.
Vahe HakobyanEditor-in-chief
Updated Oct 6, 20263 min readFact-checked
On this page
- Searchers find chances, builders order trades, validators propose blocks.
- Arbitrage, liquidations and sandwich attacks are common MEV types.
- Block space is scarce, and order changes who wins on price.
The term began in 2020 as miner extractable value, when miners built blocks. It became maximal extractable value because validators can capture this profit too.
What is maximal extractable value?
MEV is not a coin or a fee. It is the profit available from how a block is built. The producer chooses which transactions go in and in what order, and that choice can pay more than the standard block reward.
How does MEV work?
MEV exists because block space is scarce. Many transactions compete for the same block, and order decides who gets a better price or whose loan is closed. Several roles compete for that profit.
- Searchers watch pending transactions for chances to profit.
- Builders group transactions and set the block order.
- Validators propose the block and earn a reward.
- Arbitrage buys low on one exchange and sells high on another.
- Liquidations close a loan when collateral falls too low.
- Sandwich attacks trade around your swap to worsen its price.
How does MEV affect users?
For ordinary users, MEV usually shows up as a worse swap outcome. A sandwich attack can move the price against you before your trade executes. Your trade may also fail when another trader takes the chance first.
How is MEV different from front-running?
Front-running is one type of MEV. It means seeing a pending trade and paying to get your own trade in first. MEV is broader because it counts any profit from ordering transactions, even when nobody copies a trade.
Frequently asked questions
Usually the searcher who spots the chance, the builder who orders the block and the validator who proposes it. Users can gain when arbitrage corrects a price on a decentralized exchange.
A tight slippage limit, a limit order or a swap sent through a private channel can lower your exposure. None of these removes the risk.
No US law names MEV as illegal on its own. Enforcement turns on the conduct, such as fraud or market manipulation.
Yes. Any chain where order changes outcomes can have MEV. Bitcoin uses miners instead of validators, and its trading is simpler.
