MEV and Block Building

MEV, or maximal extractable value, is the extra profit available from ordering transactions rather than merely including them. On Ethereum, transparent mempools and highly composable DeFi made this a permanent part of block production, not a niche edge case.

Searchers are bots with fast infrastructure and good simulations. They scan pending activity, predict outcomes across AMMs and lending markets, and turn those predictions into bundles worth paying for. Builders then compete to make the highest-value block out of that order flow.

MEV is not automatically malicious. Arbitrage can tighten prices and liquidations keep lending protocols solvent. The harmful side appears when users are exploited through sandwiching, censorship, or excessive centralization around relays and builders. That is why Ethereum research keeps circling around proposer-builder separation, encrypted mempools, and fairer inclusion mechanisms.