Polymarket’s 2026 midterm election website organized on a laptop in Forest Hills, New York, USA, on Wednesday, October 28, 2026. Gabby Jones | Bloomberg | Getty Images Some users of international exchange prediction market platform Polymarket had funds stolen from their accounts due to a hack by an anonymous third-party provider. Polymarket contacted the authorities and promised to refund any affected merchants. It is unclear how many users were affected. The company’s US platform was not compromised. Traders first reported on social media platforms that they were seeing unauthorized withdrawals from their accounts on Thursday afternoon. In response, the company stopped operating on its international platform. Polymarket said it had fixed the issue and operations resumed at 3:00 p.m. ET. A person familiar with the matter told CNBC that the issue was due to a hack of DebugBear, a website performance monitoring platform. DebugBear in a post on X said it was affected by a security incident on Thursday. The person familiar with the Polymarket outage said the company referred the matter to authorities in the United Kingdom, since that is where DebugBear is based. DebugBear did not immediately respond to a request for comment. An analysis of publicly available data by two analytics firms, Betting Intelligence and Polysights, provided to CNBC said that one account at Polymarket withdrew at least $2.7 million from 710 other wallets on Thursday. Polymarket International Prediction Market Exchange operates as a decentralized financial platform on the Polygon blockchain and is not regulated in the U.S. The outage comes just days before the company’s international and U.S. exchanges are expected to see higher volumes during the U.S. midterm elections on November 3. A similar incident occurred in June, when Polymarket said a third-party vendor had been “compromised” and that the company would refund affected users. Disclosure: CNBC and Kalshi have a business relationship that includes customer acquisition and a minority investment.
