Maximal Extractable Value

MEV is the profit that block producers (and the ecosystem of actors around them) can extract by including, excluding, or reordering transactions within a block. It is an emergent economic phenomenon --- not a protocol feature, not a bug, but a consequence of how blockchains batch and sequence transactions.

In traditional finance, exchange operators enforce strict price-time priority. On a blockchain, no such guarantee exists by default. The entity assembling the next block has discretionary power over ordering, and that power has economic value. MEV is the study and quantification of that value.

The concept connects directly to market microstructure: adverse selection, information asymmetry, and the cost of transacting all appear in DeFi, but with the mempool replacing the order book as the site of strategic interaction.

Why It Matters

MEV represents a hidden tax on every DeFi user. When a trader submits a swap, the price they receive is not solely a function of pool state --- it also depends on who else is watching the mempool and what they choose to do with that information. Understanding MEV is prerequisite to understanding the true cost of decentralized trading.

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