Polymarket suspends trading after third-party supply chain attack
Polymarket temporarily halted trading on its international platform on October 29, 2026, after hackers compromised a third-party provider in its supply chain. The breach exposed user funds and caused a major API outage. Users reported stolen funds from their wallets. Polymarket pledged to fully reimburse all affected traders. The platform did not name the third-party provider involved, specify how many users were affected, or disclose the total amount stolen.
This is Polymarket's fourth third-party supply-chain breach on its international platform in the running coverage, each forcing treasury reimbursement. The repeated hits strain reserves and give competitors like Kalshi and ForecastEx concrete losses to cite when arguing that regulated custody infrastructure prevents recurring thefts.
Traders choosing between venues must weigh whether Polymarket's speed and breadth outweigh its supply-chain vulnerabilities. The shared Polymarket brand means trust damage on the offshore site bleeds into the CFTC-regulated US exchange operated through QCX LLC. Each breach sets a cost benchmark the whole industry will be measured against. A delayed or partial payout would amplify the argument that registration matters more than quick launches.