Polymarket Faced $10M Fraud Attempt as Compliance Scrutiny Intensifies, WSJ Reports

Fraudsters attempted to move at least $10 million through Polymarket’s US platform using stolen debit cards in February, according to a Wall Street Journal report relayed on September 20 by The Block. The payment processor reportedly rejected more than 80% of deposits as potentially fraudulent at one point, creating an immediate constraint on customer funding activity.

Stolen-card deposits triggered processor rejections on Polymarket US

The reported attempt focused on Polymarket’s US operation and involved debit-card details that had been stolen. The Journal’s reporting, as summarized by The Block, put the attempted volume at no less than $10 million.

More than four in five deposits were reportedly flagged by the processor at one stage. The report does not establish how much of the attempted activity, if any, was completed, nor does it specify the identity of the processor.

WSJ report links compliance concerns to growth push

The Journal’s reporting raised questions about Polymarket’s internal approach to compliance. It said CEO Shayne Coplan urged employees to prioritize growth and address any potential regulatory fines later, according to current and former employees cited by the Journal; Investing.com reported the account.

The alleged stolen-card activity is presented alongside a broader tension between expansion and controls.

The employee claims are attributed to the Journal’s sources and were not independently substantiated in the reporting provided.

Account compromise followed documented fraud-control commitment

A separate security incident in July reportedly compromised nearly 500 Polymarket user accounts through stolen personal information, including Social Security numbers. The attackers did not need to know the affected users’ usernames or passwords, according to The Block’s account of the Journal report.

Before those reported 2026 incidents, Polymarket US set out a formal fraud-monitoring commitment in a December 23, 2025 rule submission to the Commodity Futures Trading Commission. In the submission, the company said its compliance department would monitor and review incidents involving abuse or fraud.

The reported February deposit activity and July account compromise therefore test the fraud-control framework Polymarket US had publicly described to the regulator.

Disclaimer: This article is provided for informational purposes only. It is not offered or intended to be used as legal, tax, investment, financial, or other advice.