Allegation of a $10 million fraud attempt on Polymarket

It was alleged that the U.S. operations of the prediction market platform Polymarket were the target of a multi‑million‑dollar fraud attempt carried out using stolen bank cards. In transactions that began in February, at least a suspicious cash movement of $10 million was detected, but it was unclear whether the entire amount had actually been stolen.

Thousands of Transactions Attempted with Stolen Cards

According to the claim, fraudsters transferred money from stolen bank cards to Polymarket accounts and then used those funds to place bets on the platform. They then aimed to move the resulting profits to other cards or accounts they controlled.

It was reported that the payment company Checkout.com, which notified Polymarket of suspicious activity, rejected more than 80 percent of deposit requests processed during a certain period on suspicion of fraud.

According to a source close to the matter, a significant portion of the attempts failed. About seven users were linked to most of the suspicious transactions, and one of them reportedly tried to execute roughly 4,000 separate deposit operations.

In contrast, it remained unclear how much of the $10 million in question had actually been withdrawn from the platform.

Withdrawal System Sparks Debate

During a period of heightened fraud attempts, it was alleged that some real users on the platform also experienced delays in their withdrawal requests.

It was reported that Polymarket later removed the policy that required users to withdraw funds only to the same payment source. Some employees warned that this change could increase fraud and money‑laundering risks.

Company executives were said to argue that other security controls were sufficient to manage the risk.

It was noted that the policy is not a legal requirement for prediction markets, though it is a common security practice in the financial sector. An internal review by Sullivan & Cromwell law firm found that Polymarket complied with regulations.

Separate Attack Targeting Hundreds of Users

It was also alleged that Polymarket's security problems were not limited to this.

In a separate incident that reportedly occurred at the end of July, it was reported that the accounts of about 500 users were targeted. It was alleged that attackers tried to access some accounts using compromised personal data without having usernames or passwords.

A Polymarket spokesperson announced that the company would cover the funds lost by users in this incident.

It was stated that the company had recently added experienced staff in risk management and strengthened its security infrastructure. Following new measures such as limiting the number of bank cards that users can link to their accounts, fraud rates were said to have fallen back to industry normal levels in May.

It was alleged that Polymarket senior executive Shayne Coplan instructed employees to focus on growth targets and to address potential regulatory sanctions at a later stage. The company said it remains committed to creating fair and transparent markets and is cooperating with regulatory bodies and law enforcement.