Polymarket Faced $10 Million Stolen-Card Fraud Attempt, WSJ Reports

Fraudsters attempted to move at least $10 million through Polymarket's U.S. platform in February using stolen debit cards to place wagers and attempt withdrawals, according to a Wall Street Journal investigation covered by The Block on September 20, 2026. The Commodity Futures Trading Commission (CFTC) is investigating the prediction market in connection with the episode, which reportedly unfolded as chief executive Shayne Coplan urged employees to prioritize growth over compliance.

Key takeaways

• Stolen debit cards were used in an attempt to move at least $10 million through Polymarket US in February, per reporting on the Wall Street Journal investigation.
• Payment processor Checkout.com rejected more than 80% of Polymarket US deposits at the peak of the activity, compared to a standard industry rate of roughly 1%.
• The CFTC is investigating Polymarket in connection with the fraud episode and other platform issues.
• Polymarket reportedly brought fraud rates closer to industry norms by May after limiting connected debit cards and hiring fraud-prevention firm Riskified.

Stolen cards, rejected deposits and pressure from Visa

The scheme reportedly worked by linking stolen debit cards to Polymarket US accounts, placing wagers and then attempting to withdraw the money. Checkout.com, the platform's payment processor, flagged the activity and at its peak rejected more than 80% of Polymarket US deposits, compared to a standard industry rate of roughly 1%, according to Blockonomi.

Visa pushed payment processors, including Checkout.com, to curb fraudulent transactions and tighten payment screening on prediction markets, crypto.news reported. The reporting also said Polymarket had dropped an anti-money-laundering safeguard that originally required withdrawal funds to return to the same payment source used for the deposit, a control designed to make it harder to cash stolen money out to a different account.

CEO reportedly told staff to keep growing

Coplan reportedly told employees to prioritize growth and expansion over compliance and to deal with potential regulatory fines later. According to reporting on the Journal's findings carried by The Daily Hodl on September 21, 2026, Coplan reportedly told staff to keep growing and deal with any regulatory fines later. Polymarket has not confirmed the remark.

Polymarket has defended its controls. "Our market integrity framework includes processes to detect, review and respond to suspicious activity," a company spokesperson said in remarks carried by The Block. A spokeswoman added: "We are proud of our key leadership hires and continuous infrastructure upgrades and we have quickly scaled and remain focused on growing responsibly at the frontier of finance, tech, and culture."

An internal investigation conducted by law firm Sullivan & Cromwell concluded that Polymarket had complied with regulations, The Block reported.

CFTC scrutiny and a regulated U.S. footprint

The CFTC investigation adds to the company's prior history with the regulator. Polymarket paid a $1.4 million penalty to the CFTC in 2022 for offering unregistered event-based binary options. Its U.S. platform now operates under designated contract market status granted to QCX LLC on July 9, 2025, which places it directly under CFTC oversight.

Cleanup measures and other security incidents

By May, Polymarket had reportedly brought fraud rates closer to industry norms by limiting connected debit cards and hiring fraud-prevention firm Riskified, according to crypto.news.

The card scheme was not the platform's only security problem this year. In June, Polymarket confirmed that malicious code was injected into its website via a compromised third-party vendor, resulting in stolen funds from some users, according to U.Today. In a separate July incident, attackers used stolen personal information, such as Social Security numbers, to compromise nearly 500 user accounts.

New executives and IPO ambitions

The scrutiny lands as Polymarket builds out its leadership team. The company appointed Warren Jenson as chief financial officer and Travis VanderZanden as chief growth officer, U.Today reported. Meanwhile, The Block reported that Polymarket is seeking roughly $1 billion in financing at a $21 billion valuation ahead of a potential 2027 IPO.

Frequently asked questions

Is Polymarket under investigation?

Yes. The CFTC is investigating Polymarket in connection with the February fraud episode and other platform issues, according to The Block and other outlets covering the Wall Street Journal investigation.

Were user funds or accounts affected?

Reported incidents beyond the card scheme include a June website compromise via a third-party vendor that resulted in stolen funds from some users, per U.Today, and a July incident in which attackers compromised nearly 500 user accounts using stolen personal information such as Social Security numbers.

What has Polymarket changed since the fraud wave?

Polymarket reportedly limited connected debit cards and hired fraud-prevention firm Riskified, bringing fraud rates closer to industry norms by May, according to crypto.news.