Polymarket Halts International Trading After Unauthorized Withdrawals

Polymarket halted new trading on its international exchange on Thursday, Oct. 29, 2026, placing it in cancel-only mode and pausing relayer actions after unauthorized withdrawals. The company said a third-party provider was compromised and referred the matter to UK law enforcement. "We'll make this right and are fully reimbursing all affected traders," Polymarket posted on X. Trading paused about an hour and resumed Thursday afternoon. Polymarket US was not affected and continued operating. Loss totals remain unconfirmed by the company. Arkham data showed a suspected attacker wallet holding about $2.65 million in POL after multiple USDC.e-to-POL swaps via Relay, with funds later moved to other addresses. Bubblemaps estimated about 700 users affected and about $2.7 million stolen; Polymarket declined to confirm those figures when asked by Wired. Reports named DebugBear, a UK-based website performance monitoring company, as the provider; DebugBear posted it was impacted by an ongoing security incident and advised clients to remove its embed code. A prior June 2026 security incident caused more than $2 million in losses. In August 2026 Polymarket raised $1 billion in a round led by 1789 Capital, valuing the company at $21 billion.