Polymarket Halts International Trading After Security Breach

A security breach involving a third-party software provider disrupted Polymarket’s international platform on Thursday, Oct. 29, 2026, after users reported unauthorized withdrawals from their cryptocurrency wallets. The company temporarily suspended trading, referred the incident to British law enforcement and pledged to reimburse all affected users, while its U.S.-based platform appeared unaffected.

Polymarket said it had identified and resolved the issue on its international platform, allowing trading to resume at 3 p.m. Eastern time after an outage lasting nearly an hour, according to NBC News and CNBC. The company did not disclose the number of affected users or independently confirm the total amount stolen.

Blockchain analysis cited by multiple news outlets indicated that the incident involved millions of dollars in cryptocurrency. CNBC reported that data analyzed by two analytics firms showed one account withdrew more than $2.7 million across 710 other wallets. Separately, The Block reported that approximately $2.65 million had been taken from user wallets, citing blockchain analysis group Arkham.

A person familiar with the incident told CNBC and NBC News that the breach was linked to DebugBear, a website performance monitoring and analytics provider based in the United Kingdom. DebugBear acknowledged a security incident on Thursday but did not immediately respond to requests for comment, according to the reports.

Polymarket publicly acknowledged the third-party compromise and said it had referred the matter to law enforcement. The company also committed to compensating users who suffered losses.

"One of our 3rd party providers was compromised, and we have referred this to relevant law enforcement," Polymarket said in a post on X.

The company said it had suspended trading as a precaution while addressing the vulnerability. Its international platform operates as a decentralized finance service on the Polygon blockchain and is not regulated in the United States, according to CNBC.

Polymarket also addressed the financial impact of the incident in a separate statement, promising to reimburse affected customers.

"anyone who has been impacted will be made whole," Polymarket said in an X post.

In a subsequent post, the company reiterated its commitment to restoring users' losses, according to NBC News.

"We’ll make this right and are fully reimbursing all affected traders," the company said.

The breach came amid heightened attention on the platform ahead of the U.S. midterm elections scheduled for Nov. 3, when both its international and U.S. operations were expected to experience increased activity, CNBC reported.

NBC News reported that Polymarket was valued at $21 billion in September after a group of investors led by Donald Trump Jr. invested $1 billion in the company. The platform processes approximately $200 million in daily activity, according to the same report.

The incident also followed a similar episode in June, when Polymarket said a third-party vendor had been compromised and promised refunds to affected users, according to CNBC. The latest disruption highlights another security incident involving external software used by a major online platform.