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Polymarket freezes trading as accounts are drained
A major API outage pushed Polymarket into cancel-only mode, and one trader says $800,000 left his account.
An $800,000 drain and a freeze
A trader posting as Car said $800,000 was drained from his account, about 20 minutes before Polymarket halted all new trading. [1] The breach affected users on Polymarket's international venue. [2]
Other users reported accounts drained of thousands of dollars after positions were sold without consent. [2] CoinDesk confirmed that users with balances on the international platform saw their accounts drained. [2]
What happened on the platform
Polymarket went into cancel-only mode after its Predictions Trading API had a major outage. [2] Its status page flagged the outage at 18:05 UTC and said the exchange had moved to cancel-only mode while investigating an unnamed incident. [1]
During the freeze, users with open positions could cancel pending orders but could not buy or sell. [1] Polymarket also paused its relayer, which sends token transfers and spending approvals on behalf of users' wallets. [1]
Trading on the international platform was initially paused for several hours while the company investigated, and has since resumed. [3] Polymarket said all systems were operational as of 7:05 pm UTC. [2]
The company's response
Polymarket said anyone impacted will be made whole. [2] It declined to comment on how many traders were impacted and how much money was lost, but said it will refund impacted traders. [3]
Law enforcement in the UK was notified of the incident, according to the company. [3] Polymarket has not named a cause, victim count, or loss total for the incident. [1]
The company and its rivals
Polymarket is led by founder and CEO Shayne Coplan. [2] It recently raised $1 billion in August 2026, led by 1789 Capital, and is now valued at $21 billion. [3]
The freeze came two days after rival prediction market Predict.fun lost $400,000 to attackers. [1]
Polymarket's head of experience, William LeGate, said affected users in June were being refunded in whole. [1] The smart contracts holding user funds were not breached in June. [1]
What this means for you
If you trade on Polymarket's international platform, you are in the group affected by the breach. [2] Polymarket said anyone impacted will be made whole. [2]
If you use Polymarket US, the company's separate platform for people within the United States, the hack did not affect you. [3] Trading on the international platform has resumed, and Polymarket said all systems were operational as of 7:05 pm UTC. [3][2]
Sources
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