Polymarket temporarily suspended activity on its international exchange after a security breach at a third-party vendor in the United Kingdom allowed unauthorized access to user balances. The prediction market notified British law enforcement authorities about the intrusion and paused operations for several hours while conducting an investigation.
Vendor Intrusion and Platform Impact
Following public complaints from traders on X regarding drained balances, blockchain analytics firm Bubblemaps reported that approximately 700 accounts appeared to be compromised, resulting in roughly $2.7 million in stolen funds. While Polymarket declined to comment to WIRED regarding the precise amount lost or the total number of affected users, the company stated that it will fully reimburse the impacted traders.
The disruption was limited to Polymarket’s international platform and did not affect Polymarket US, a distinct, federally regulated exchange serving customers inside the United States. The flagship international service operates on cryptocurrency infrastructure and remains barred from operating in the US and several other jurisdictions.
Prior Incidents and Platform Growth
The platform has faced previous security challenges, including a June 2026 breach that resulted in more than $2 million in losses for participants. Since its debut in 2020, Polymarket has also been tied to legal scrutiny involving alleged insider trading. High-profile prosecutions have included charges against a Google employee accused of trading on confidential corporate information, as well as a Special Forces soldier accused of placing wagers on the capture of Venezuela’s former leader. Both defendants entered pleas of not guilty.
In August 2026, Polymarket completed a $1 billion fundraising round led by 1789 Capital, a venture capital firm where Donald Trump Jr. is a partner, bringing the prediction platform’s valuation to $21 billion.
