Polymarket halts international trading after third-party provider hack
Polymarket suspended trading on its international platform on Wednesday, October 29, after an unnamed third-party provider was compromised. The hack allowed attackers to drain some user funds. Polymarket entered cancel-only mode during the incident and referred the matter to U.K. authorities. The platform said the issue has been fixed and trading has since resumed, but did not name the provider or specify a full restoration timeline. The CFTC-regulated U.S. exchange was not affected.
The breach hit Polymarket's international platform, leaving the separate CFTC-regulated U.S. venue untouched but staining the shared brand. Traders with funds on the offshore site faced frozen positions and uncertain recovery while Polymarket investigated. The incident exposes third-party data providers as a critical vulnerability even for platforms with audited smart contracts.
Competitors like Kalshi and ForecastEx can now point to concrete losses when arguing that regulated custody infrastructure offers stronger protection. Polymarket's reimbursement promise will test its treasury and set a benchmark rivals will be measured against in future breaches. Trust damage from the offshore site bleeds into the regulated U.S. venue too, because the Polymarket name covers both.
Polymarket joins a cluster of recent breach-related halts, with related coverage showing the platform has faced multiple third-party security incidents in the past day as it tries to keep its regulated U.S. exchange distinct from offshore problems.