Polymarket resumes trading and pledges refunds after third-party security breach

Polymarket resumed international trading on Thursday afternoon following a nearly hour-long suspension caused by a security compromise of a third-party vendor.

The prediction market platform halted activity on its international site, Polymarket.com, for approximately one hour on Thursday. According to reports from NBC News and The Guardian, the company identified a breach involving a third-party provider and suspended trading "out of an abundance of caution" while implementing a fix. The platform's U.S.-based operations did not appear to be affected by the incident.

The breach has been linked to DebugBear, a UK-based company providing website performance-monitoring tools. NBC News reported that hackers gained access to funds through this software, while The Guardian noted that DebugBear’s own website became unavailable and the firm confirmed it was facing an "ongoing security incident." Polymarket has referred the matter to law enforcement authorities in the United Kingdom.

While Polymarket did not specify the amount lost, crypto news site The Block reported that roughly $2.65 million in digital assets were taken from user wallets, citing Arkham blockchain data. Some users on the platform's Discord channel claimed their wallets had been drained during the disruption. A company representative declined to comment on specific figures regarding the theft.

Polymarket has committed to fully reimbursing all affected traders, stating on X that impacted users "will be made whole." Trading officially resumed at 3 p.m. ET on Thursday. The company currently processes roughly $200 million in daily trading activity and was recently valued at $21 billion following a September investment round.

Background

The incident occurs amid a regulatory dispute between U.S. states and the Trump administration over the oversight of prediction-market betting. Polymarket recently secured $1 billion in funding from an investor group led by Donald Trump Jr.