The five second trick that drained millions from Polymarket

Researchers found 821 accounts that made $8.2 million by manipulating bitcoin prices in the final seconds before Polymarket settled its short dated contracts. Polymarket has now replaced instant snapshots with time weighted averages, but the structural vulnerability they exposed is not unique to one platform. Summary Polymarket replaced its instant price snapshot settlement mechanism with time weighted average prices on August 7, 2026, after a study identified 821 accounts that collectively made $8.2 million in settlement windows classified as likely manipulated across roughly two months of five minute bitcoin contracts. The manipulation worked by accumulating a large position on Polymarket, then placing unusually large orders on Binance in the final seconds before settlement to move the bitcoin price across the contract’s strike threshold, causing the contract to resolve in the manipulator’s favor before the price reverted. Excluding market makers, 93 percent of the losses in windows classified as manipulated fell on retail traders, and the researchers found that a bet the market treated as near certain was overturned one time in three during manipulated windows. Under the new sys...