Polymarket’s U.S. Push Hit a Payment Wall as Its Processor Rejected Over 80% of Card Deposits

In February 2026, Checkout.com rejected more than 80% of the card deposits it handled for Polymarket US as fraudulent at one point, compared with an industry benchmark of roughly 1%, according to a Wall Street Journal investigation. The processor alerted Polymarket after fraudsters linked stolen debit cards to thousands of accounts, funded wagers, and attempted to withdraw money to other cards or accounts.

The fraudsters tried to move at least $10 million through the platform, the Journal reported. Most attempted deposits failed, according to a person familiar with the episode. About seven users accounted for most of the activity, with one reportedly attempting roughly 4,000 deposits. The figure represents attempted activity, not a confirmed $10 million loss.

Polymarket US had begun admitting users from its waitlist months earlier. The U.S. business operates through QCX LLC, which the Commodity Futures Trading Commission designated as a contract market on July 9, 2025.

The Withdrawal Rule

Polymarket had required deposits made from one payment source to be withdrawn to that same source. The company later loosened the restriction after customers complained about withdrawal delays, according to the Journal.

Employees warned that removing the restriction could increase exposure to financial crime, the Journal reported. Executives maintained that other controls were sufficient, according to people familiar with the discussions.

The reporting does not establish that loosening the withdrawal rule caused the February fraud attempt.

After Checkout.Com

Separately, The Information reported in June that Visa had pressed Checkout.com to curb fraudulent Polymarket payments. The processor then demanded tighter controls from the platform, according to the report.

Polymarket subsequently limited the number of debit cards users could link to their accounts and hired Riskified, a fraud-prevention company. Fraud rates remained elevated for months but had moved closer to industry norms by May, according to a person familiar with the matter cited by the Journal.

The internal response continued. Andrew Clifford, Polymarket US’s chief compliance officer, resigned in April after sending executives a detailed report about fraud concerns, according to people familiar with the report. The company later fired U.S. CEO Justin Hertzberg, while its U.S. regulation and anti-money-laundering heads also left.

Employees also told the Journal that CEO Shayne Coplan responded to compliance concerns by telling staff to keep growing and deal with any regulatory fine later. Polymarket has not publicly confirmed that account. The company said it has procedures to detect, review, and respond to suspicious activity and cooperates with regulators and law enforcement.

The Journal reported that the CFTC was investigating the company and that employees were instructed to preserve records related to the fraud episode and other matters. The inquiry is not a public finding that Polymarket violated federal law. A separate Sullivan & Cromwell review concluded that Polymarket complied with regulations, according to people familiar with its findings.

For a U.S. prediction market still scaling its customer base, the February spike showed how quickly payment-fraud controls could become a constraint on growth.