Polymarket Resumes Trading After Third-Party Security Breach

Polymarket halted trading on its international platform on October 29 after identifying a security problem with an outside provider. The company said it fixed the issue, paused trading as a precaution and referred the incident to law enforcement in the United Kingdom. Trading resumed about an hour later.

Blockchain analytics firm Bubblemaps estimated that about 700 users were affected and roughly $2.7 million was stolen from traders’ wallets. The company did not confirm those estimates, but said anyone impacted would be made whole and that it would fully reimburse affected traders. Users had also posted complaints about lost funds.

The incident affected Polymarket’s international cryptocurrency platform, not its separate U.S. platform, according to the company. DebugBear, a UK-based website performance monitoring provider, said it was dealing with an ongoing security incident and advised clients using one of its products to remove its embed code from their websites.

Polymarket also experienced a breach in June 2026 that caused more than $2 million in losses for affected traders. The company was valued at $21 billion after raising $1 billion in August, in a round led by 1789 Capital, where Donald Trump Jr. is a partner.