Stanford Study Finds Manipulation in Polymarket Bitcoin Betting Market

Researchers at Stanford University have found signs of manipulation in the Polymarket five-minute Bitcoin betting market. The study analyzed contract data over approximately two months and discovered repeated one-sided trading pulses on the Binance exchange that briefly affected Bitcoin prices just seconds before the betting ended, benefiting those with aligned positions. The researchers termed this pattern "temporary manipulation to drive up spot prices" and pointed out that such contracts have structural vulnerabilities, allowing participants to influence the outcome by trading the underlying asset itself. A Polymarket spokesperson stated that the platform uses multiple independent price oracles to ensure accuracy and plans to transition some markets to a settlement method with longer time windows next year to enhance market integrity. The study estimated that suspected manipulators profited about $8.2 million over the two months, primarily from losses incurred by retail traders. Similar patterns were not evident in the 15-minute market, where longer time windows make it more difficult to influence outcomes.