Polymarket Hit by $10M Fraud Attempt Under Federal Probe

Polymarket's U.S. platform was targeted in a major fraud attempt in February 2026, with criminals using stolen debit cards to try to move at least $10 million through the prediction market. The incident, which is now under federal investigation, has raised questions about the company's internal controls and its rapid expansion. According to reports, fraudsters linked stolen payment cards to thousands of new accounts on the Polymarket US platform, deposited funds, placed bets, and then attempted to withdraw winnings to cards or accounts they controlled. The scale of the attack overwhelmed payment systems. Checkout.com, Polymarket's payment processor, at one point rejected more than 80% of the deposits it handled for the platform as fraudulent. That rate was far above the industry benchmark of roughly 1%. The compliance team at Polymarket escalated concerns about the surge in suspicious transactions to CEO Shayne Coplan. Current and former employees alleged that Coplan responded by urging the company to prioritize growth and deal with any potential regulatory fines later. Polymarket has not publicly confirmed that Coplan made such a statement.