- Polymarket fraud attempts targeted at least $10 million through stolen cards.
- Checkout.com reportedly rejected more than 80% of suspicious deposits.
- Polymarket later tightened card restrictions after the February attack.
Polymarket fraud attempts targeted the company’s US platform in February 2026 using stolen debit cards. The Wall Street Journal reported that criminals attempted to move at least $10 million through thousands of accounts. Most deposits reportedly failed, leaving the final amount stolen unclear. The episode also exposed concerns around payment controls and compliance procedures.
Polymarket Fraud Attack Exposed Weaknesses in Payment Controls
The Polymarket fraud operation involved stolen debit cards linked to newly created US accounts. Attackers funded wagers before attempting withdrawals to other cards or accounts they controlled.
Checkout.com, Polymarket’s payment processor, reportedly rejected more than 80% of deposits as fraudulent. That figure was far above the industry benchmark of about 1%.
Around seven users accounted for much of the activity, according to people familiar with the incident. One user reportedly attempted roughly 4,000 deposits.
The Polymarket fraud wave emerged as the platform faced complaints about delayed withdrawals. Compliance staff were also handling a growing backlog of withdrawal requests.
Polymarket Fraud Concerns Grew After Withdrawal Rule Change
Polymarket later removed a safeguard requiring withdrawals to return to the original payment source. The control can reduce risks involving stolen cards and mismatched withdrawals.
Some employees reportedly warned that the change could increase money-laundering risks. Executives maintained that other controls could address suspicious transactions.
The Polymarket fraud incident was followed by additional security concerns in July. Nearly 500 users were reportedly exposed through an account-registration vulnerability involving stolen personal information.
The company later restricted the number of debit cards users could connect. By May, fraud rates had reportedly returned to industry levels.
The Polymarket fraud allegations come as the company expands its US business and prepares for further fundraising. Its compliance leadership also changed, while the company added risk-management staff and strengthened internal procedures.
Disclaimer: This article is for informational purposes only and does not constitute financial advice. CoinCryptoNewz is not responsible for any losses incurred. Readers should do their own research before making financial decisions.
