29 Oct 2026 · Prediction markets · Desk briefing · Written by GammaPredict Research · All news

Polymarket paused international trading after a third-party compromise

On 29 October 2026 Polymarket stopped trading on its international site after traders reported withdrawals they had not authorized. The company says one third-party provider was compromised, that the issue is fixed, that affected traders will be reimbursed, and that it has referred the matter to law enforcement. CNBC reported that the US platform was not compromised.

What Polymarket said

The statement carried by NBC News, CoinDesk and Decrypt says the company identified and fixed an issue on the international platform, Polymarket.com. One third-party provider was compromised. Anyone affected will be made whole. A later line, also carried by NBC, says the company will fully reimburse affected traders.

Before that, the exchange was in cancel-only mode: existing orders could be cancelled, and new orders were not processing. Relayer actions were paused. Reuters reported the trading API outage from the status page. NBC News and CNBC say trading resumed at about 3:00 p.m. US Eastern on 29 October, 19:00 UTC, 22:00 Moscow, after roughly an hour offline.

A Polymarket spokesperson told CNBC the matter was referred to UK law enforcement, because that is the country of operation for the third-party provider. Polymarket has not published, in these reports, a count of affected accounts or an official dollar loss.

What reporters added

The Block and Decrypt, citing Arkham, said a wallet they identified as a suspected attacker held about $2.65 million in POL after swaps from USDC.e. Decrypt names the address 0x3F99139F1C5854bb628c2e576Aaf638e99dFfc18. That figure is an on-chain snapshot those desks attributed to Arkham. It is not a loss total published by Polymarket. The Block also reported that funds then moved to other addresses.

Decrypt reported a trader on X who said an account lost about $800,000, and that the same trader said another account lost about $600,000. Those are the trader’s claims. We have not verified them.

Decrypt and Hudson Rock said a performance-monitoring script associated with DebugBear, loaded on the international site, contained logic aimed at a logged-in trading session: find the session, and attempt to sell or move assets. Hudson Rock said Polymarket’s production build recorded removal of that integration, and that the firm had not established how the compromise started or how many users were affected. Polymarket’s own statement, in the lines carried by CNBC and NBC, says “a third-party provider” and does not name the vendor.

What this does not change tonight

The editorial ranking stays where it was this morning. Gamma Score is not a security audit, and an afternoon headline is not a new score. The international site and the US platform are different products. CNBC and NBC say the US platform was not the one halted.

This briefing does not say the trading contracts were drained at the protocol layer. The company’s account is a provider compromise, a halt, a fix, and reimbursement. We have not inspected wallets ourselves.

If you used the international site today

Read Polymarket’s own posts and status page. The company says affected traders will be reimbursed. Reimbursement instructions that arrive in a reply, a direct message, or a lookalike domain are a second problem. The Polymarket review now points here. Readers comparing a US cash venue with the crypto board still start at Polymarket vs Kalshi. This incident is an access risk on the international site, separate from that product difference.

Editorial briefing, 29 October 2026. Figures attributed to other desks are labelled. This is not a chain audit and not financial advice.