Compromised Software Caused Polymarket To Pause Trading. Some Users Said Funds Had Been Stolen.

Prediction market platform Polymarket paused trading on its international exchange on Thursday because of what the platform called a compromise of third-party software. Some users of the international platform said that they had had funds stolen.

"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. Out of an abundance of caution, we have temporarily halted trading," the platform's X account posted on Thursday.

Trading was paused for nearly an hour, but resumed at approximately 3PM ET, the platform confirmed.

Different reports indicated that the incident led to approximately $2.65 million in cryptocurrencies being taken from Polymarket users' wallets in a matter of minutes. Conor Grogan, the senior director at Coinbase - the largest cryptocurrency exchange in the U.S. -, reported that just under 1000 accounts had been affected by the hack.

The "relevant law enforcement" contacted were British authorities, as the compromise appears to have originated from the United Kingdom. The hackers are said to have accessed the funds through software from DebugBear, which describes itself as a "UK-based site speed monitoring service."

We are aware of a security incident affecting DebugBear and are treating it as a top priority. We have engaged specialist cyber incident response support and will work with affected customers directly," the British company said on Thursday.

Polymarket's U.S. platform appears to have remained unaffected by the breach.

Polymarket has been targeted in a similar manner before. In June, the prediction market disclosed that it had been subject to a supply chain attack that caused the theft of about $3 million from users' accounts. However, only 15 customers were said to have been affected in that instance.

Prediction markets in general have significantly increased in popularity recently. Polymarket's valuation jumped by 40% from $15 billion in April to $21 billion at the end of the summer.

On the other hand, Kalshi, Polymarket's main competitor, announced a valuation of $40 billion on Thursday after its latest $1 billion funding round.

However, both companies have come under significant political scrutiny in the buildup to the midterms. Polymarket is said to have investigated dozens of bets on its platforms related to the elections, and both prominent Republicans and Democrats have raised concerns about the potential for both Polymarket and Kalshi to facilitate electoral insider trading.

Republican Senator John Curtis and Democrat Senator Elizabeth Warren articulated these concerns in a letter to the CEOs of both companies on Wednesday.

"In the lead up to the November 2026 midterm elections, we write to express concerns about electionrelated prediction markets and to request specific information about your companies' efforts to prevent insider trading, market manipulation, and wagers based on material nonpublic information," the introduction to the letter read.