Polymarket is facing renewed scrutiny after fraudsters allegedly used stolen debit cards to attempt at least $10 million in transactions on its U.S. prediction-market platform earlier this year.
The incident emerged as the company accelerated its U.S. expansion. Payment processor Checkout.com reportedly rejected more than 80% of deposits it handled as fraudulent at the peak of the activity in February. That compared with an industry rate of roughly 1%.
Stolen Cards Targeted U.S. Platform
The alleged scheme involved criminals linking stolen debit cards to thousands of Polymarket U.S. accounts. They then deposited funds, placed wagers and attempted to withdraw money to accounts or cards they controlled.
The $10 million figure represents attempted transactions rather than confirmed losses. Public reporting has not established that Polymarket or its customers ultimately lost that full amount.
The episode also raised questions about the platform’s fraud controls during a period of rapid growth. People familiar with the matter said compliance employees raised concerns internally as rejection rates surged.
Polymarket Strengthens Risk Controls
Fraud activity reportedly remained elevated for several months before falling toward industry norms. Polymarket subsequently restricted the number of debit cards users could connect and brought in additional antifraud resources.
The company has also expanded its compliance, investigations and risk-management operations. Its U.S. platform operates through a federally regulated exchange and maintains rules prohibiting fraud, market manipulation and other prohibited activity.
The reported fraud episode comes amid broader regulatory attention toward prediction markets. Polymarket previously settled with U.S. regulators over its operation of event-based contracts and now faces continued scrutiny as the sector expands.
For Polymarket, the incident highlights a familiar challenge for financial platforms: rapid user growth can increase transaction volume while also creating new opportunities for payment fraud. The company is now operating with expanded controls as it seeks to build its U.S. business.
