Research: Polymarket's "informed" traders have reaped $143 million in illicit profits since 2024.

Researchers at Columbia Law School and the University of Haifa analyzed most of Polymarket's trading data between 2024 and 2026, finding over 210,000 suspicious trades that generated $143 million in profits for "informed" traders. Published this month, the study is the first to estimate the total profits of suspicious accounts. Researchers used five criteria related to trading timing and bet amount to screen accounts that made large bullish bets shortly before news releases. The study defined these actions as "informed" trading rather than "insider" trading because some of the flagged large trades occurred in markets with numerous influencing factors, such as those related to the 2024 US election. Most of the top 20 most suspicious trades flagged were related to the 2024 election results, involving approximately $16 million in profits; the remainder involved Federal Reserve decisions and sporting events. Harry Crane, a statistics professor at Rutgers University, questioned the study's methodology, arguing that its suspiciousness ranking relied too heavily on profitability. The study authors acknowledged that the methodology may have included over- or under-inclusion scenarios and characterized the identified suspicious trading volume as a "conservative lower bound estimate of abnormal profits." Polymarket announced earlier this month a ban on trading using "stolen confidential information" and "illegal tips," but its offshore exchange does not collect user names or other identifying information, and the method of enforcement remains unclear.