Polymarket has resumed trading following a temporary suspension of its international service due to a security breach involving a third-party provider. Trading activities were halted on October 29 after some users reported unauthorized withdrawals from their accounts. The company acknowledged the incident and assured that it would compensate all users affected by the breach.
An investigation is currently underway by UK authorities, although Polymarket has not revealed the specific financial impact of the incident. Reports indicate that numerous traders experienced unauthorized withdrawals, with blockchain analytics firm Bubblemaps estimating around 700 users were impacted, leading to total losses of approximately $2.7 million.
The compromised third-party vendor has been identified as DebugBear, which specializes in monitoring website performance. Following the discovery of the incident, DebugBear notified its clients using its Real User Monitoring service to remove related code from their websites. As of now, investigators have yet to disclose how the breach occurred or the total extent of the damage.
After pausing its international platform for an investigation, Polymarket resumed trading on Thursday after resolving the issue. The company confirmed that affected users would receive compensation, though it has not specified the number of compromised accounts or the total compensation amount. Importantly, the security breach did not affect Polymarket's separate platform for US users.
This incident marks the second security breach involving Polymarket, following a June 2026 event where an external service provider facilitated hackers' access to applications, resulting in the theft of approximately $3 million from users. This latest breach serves as a reminder of the risks associated with third-party software; a secure site does not guarantee that external applications won’t compromise user data. Polymarket has committed to covering the losses of impacted traders as the investigation continues.
