Polymarket put its international exchange into cancel-only mode on Thursday afternoon after users reported funds leaving their accounts without their permission. The company later said one of its outside providers had been compromised.
Polymarket’s status page posted its first notice at 2:05 p.m. ET: “The exchange is currently in cancel-only mode and relayer actions paused while we investigate an incident.” In cancel-only mode, traders can pull open orders but can’t place new ones. Relayers are the services that submit users’ signed transactions to the blockchain.
At 2:33 p.m. ET, the company’s Polymarket Traders account on X said: “We’ve identified & fixed an issue impacting our international platform, Polymarket.com. One of our 3rd party providers was compromised, and we have referred this to relevant law enforcement. Anyone who has been impacted will be made whole.” The status page carried the same statement and added that “out of an abundance of caution, we have temporarily halted trading and are working to bring the platform back online.”
At 2:54 p.m. ET it said trading would resume at about 3 p.m. Six minutes later it posted: “Trading is now fully back online. We’ll make this right and are fully reimbursing all affected traders.” The status page marked the incident resolved at 3:05 p.m. ET, about an hour after the first notice.
What hasn’t been confirmed
- The amount. Polymarket hasn’t published a loss figure, and a representative declined to comment on one to NBC News. The Block and Decrypt, citing Arkham data, reported that a wallet identified as the suspected attacker’s held about $2.65 million in POL after a series of swaps out of USDC.e. That is a wallet balance, not a confirmed tally of losses. The Wall Street Journal, as cited by Quartz, counted more than $2.5 million taken from user accounts in over 900 transactions. Two analytics firms, Betting Intelligence and Polysights, told CNBC that at least $2.7 million was withdrawn across 710 wallets.
- The provider. Polymarket hasn’t named it.
- Who was affected. The company hasn’t said how many traders were hit. Its statements refer only to Polymarket.com, its international platform, and CNBC reported that the U.S. platform was not compromised.
Polymarket hasn’t said when reimbursements will be paid or how they will be calculated.
This isn’t the platform’s first vendor-related incident. In June, Polymarket said a third-party vendor had been compromised and promised to refund affected users, according to CNBC and Decrypt.
The outage came five days before the U.S. midterm elections on Nov. 3, when Polymarket’s international and U.S. exchanges are both expected to see heavier trading.
Sources: Polymarket status page; Polymarket Traders on X; The Block; Decrypt; CNBC; NBC News; Quartz