Polymarket briefly halts trading after third-party compromise and reports of stolen user funds

Predictions markets platform Polymarket was forced to halt trading on its international platform Thursday for nearly an hour because of what it said was a third-party compromise.

There were also unconfirmed reports from users on Polymarket’s Discord channel who said their wallets had been drained.

While Polymarket did not confirm that users had lost money, it said “anyone who has been impacted will be made whole.”

“We’ll make this right and are fully reimbursing all affected traders,” the company said in a subsequent post on X.

Crypto news website The Block reported some $2.65 million in cryptocurrencies had been siphoned from the platform, citing data from blockchain analysis group Arkham.

In a statement posted on its X account, Polymarket said it had identified and fixed an issue affecting its international platform, Polymarket.com.

“One of our 3rd party providers was compromised, and we have referred this to relevant law enforcement,” Polymarket said.

“Out of an abundance of caution, we have temporarily halted trading & are working to bring the platform back online,” it added.

Trading began again at 3 p.m. ET after nearly an hour offline.

Polymarket’s U.S.-based platform did not appear to be affected by the breach.

Compromises of third party vendors are a very common way malicious actors gain access to large platforms and websites. But Polymarket’s acknowledgement that hackers succeeded in stealing money from its users makes this a significant breach.

Polymarket was valued at $21 billion in September after a group of investors led by Donald Trump Jr. invested $1 billion into the platform.

The platform, along with rival Kalshi, have become to subject of an intense, multi-million-dollar battle between U.S. states and the Trump administration over who gets to regulate the prediction-market betting that occurs on the sites.

The platforms also continue to fight off insider-trading threats. Earlier Thursday, Bloomberg News reported Polymarket was investigating reports of suspicious bets made amid Israel’s closely watched elections.

It is also investigating “dozens” related to the U.S. midterms, according to the company’s head of global intelligence and investigations, Shana Bautista.

Earlier this month, Kalshi said it was looking into suspicious bets involving Trump’s choice of press secretary.

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