MEV-Share Mechanics

The MEV Problem

MEV (Maximal Extractable Value) is profit that block producers and searchers extract from transaction reordering: sandwiching swaps, frontrunning arbitrage, capturing liquidations. Historically, all this profit went to searchers and block producers. The user whose swap was sandwiched paid the cost; the searcher who sandwiched them kept the profit. MEV-Share, launched by Flashbots in 2023, changes this: users can opt in to share their transaction metadata with searchers in exchange for a kickback of any MEV the searcher captures.

How It Works in Practice

User submits a transaction through an MEV-Share-enabled RPC (Flashbots Protect, MEV Blocker, Beaverbuild's user RPC). The RPC reveals selected hints (e.g., 'someone wants to swap a million USDC for ETH') to searchers, without revealing the full transaction. Searchers bid to capture the resulting MEV; the winning bid commits to paying the user a share of the captured profit. The user's transaction settles; the searcher's bundle executes alongside it; the kickback is delivered.

Why Users Should Care

Two reasons. First, **structural MEV protection**: if your transaction is going through MEV-Share, it's not in the public mempool, so it can't be sandwiched by adversarial searchers. Second, **kickback**: you receive a portion of MEV that would otherwise go entirely to searchers. The kickback isn't huge for small trades — a few dollars to tens of dollars on typical swaps — but it's structurally yours, where previously you paid for sandwich attacks and got nothing.

• Old model: user signs tx → mempool → searchers extract MEV → user pays the cost
• MEV-Share: user signs tx → private RPC → searchers bid for MEV → user shares the profit
• Available via Flashbots Protect, MEV Blocker, Beaverbuild RPC, and others
• Structural protection + small kickback for normal users