Express Relay is Pyth's attempt to fix a specific MEV problem: on most chains, when a protocol creates an opportunity (a liquidation, an arbitrage), the value of executing it accrues to whoever wins the block — typically a validator or block builder, not the protocol that surfaced the opportunity. Express Relay flips that by letting protocols run their own auctions for priority access to their flow.
How it works at a high level
A protocol that wants to use Express Relay registers with the system. When an MEV-bearing opportunity appears (e.g. a liquidation becomes available), the protocol exposes it through Express Relay, and searchers bid for the right to execute it. The winning bid pays the protocol, not the block proposer. The protocol can then return that value to its users — for example, a lending market can pass auction proceeds back to depositors instead of seeing them captured externally.
Why this matters
MEV redirection is one of the most active areas in protocol design. Most existing solutions live at the block-builder or validator layer; Express Relay attempts the same redirection at the protocol layer, which is portable across chains and doesn't require changes to consensus. It's intentionally a more focused tool than a generic order-flow auction.
What to verify
The product page on Pythscan links to the Pyth docs section on Express Relay; the docs are the canonical source for current integrations and on-chain addresses.