Polymarket users reported stolen funds on October 29, with some claiming losses of hundreds of thousands of dollars , prompting the prediction market platform to restrict trading. The company said a compromised third-party provider affected its international exchange and pledged to reimburse affected users.
Users first flagged unauthorized withdrawals on social media that afternoon. Polymarket entered cancel-only mode , paused relayer actions and temporarily halted international trading as a precaution during its investigation. Its U.S. platform was not compromised .
An analysis of public data by Betting Intelligence and Polysights found that one Polymarket account withdrew at least $2.7 million across 710 other wallets on October 29.
Polymarket investigates stolen funds linked to vendor compromise
Polymarket said it identified and fixed an issue involving a compromised third-party service provider on its international platform. The company referred the incident to law enforcement and promised full reimbursement for affected traders.
A person familiar with the matter told CNBC that the compromise involved DebugBear, a website performance monitoring platform, and that Polymarket referred the case to U.K. authorities because DebugBear is based there. DebugBear separately confirmed in a post on X that it experienced a security incident on October 29.
The reports of stolen funds at Polymarket follow a previous third-party vendor breach in June. That incident led to approximately $3 million in stolen user funds. Polymarket said it fixed that earlier vulnerability and would fully reimburse affected users.
The international exchange operates on the Polygon blockchain as a decentralized finance platform and is not regulated in the U.S. The disruption occurred ahead of the U.S. midterm elections on November 3 , when both exchanges are expected to see heightened volumes.
Polymarket said international trading resumed at 3 p.m. ET on October 29 after it fixed the issue on its end.
Article produced with the assistance of artificial intelligence and reviewed by the editorial team.
