A company that keeps data on Ethereum mempools around the world, Blocknative, may have an explanation for the "zero-bid" attack on MakerDAO on Black Thursday. Mempools are a holding bin for transactions waiting to get mined into blocks. Under market stress, they tend to get clogged. Blocknative found an endless stream of clever, worthless transactions in mempools on the day of the attack, apparently designed to make it hard for transactions to get through. Falling ETH prices triggered auctions of collateral on MakerDAO. Because the mempools were clogged, bidders could not get bids on those auctions through in many cases, allowing attackers to win ETH collateral with bids worth $0. The attackers walked away with $8.3 million