Polymarket reforms Bitcoin contracts, Binance trading spikes drop after 60-second average settlement

Polymarket replaced its single-snapshot Bitcoin contract settlement with a 60-second time-weighted average price (TWAP) on August 14, 2025. A study by Guangzhe Wang found that Binance trading volume concentrated in the final ten seconds of five-minute windows under the old single-snapshot rule dropped to 3.02% under the new 60-second average regime, with no systematic migration to earlier bins in the first three weeks. The October 27 contract, using Chainlink's BTC/USD 60-second TWAP, settles when the ending benchmark is at least as high as the opening benchmark.