Priority Gas Auction (PGA)
A Priority Gas Auction (PGA) occurs when multiple searchers compete for the same MEV opportunity by repeatedly submitting transactions with progressively higher gas prices, attempting to position their transaction before competitors. PGAs are economically wasteful — searchers bid up to the total value of the opportunity, converting what could have been profit into gas fees paid to the block proposer. A significant portion of MEV is burned through PGA competition rather than captured by searchers. PGAs also create network congestion as hundreds of failing bids are propagated through the mempool. Flashbots and similar MEV auction systems were introduced partly to replace open-mempool PGAs with sealed-bid auctions where only the winning bundle lands on-chain, eliminating the wasteful bidding cascade. The shift from PGA-style public competition to private order flow markets has been one of the largest structural changes in Ethereum's MEV landscape.