Comer Probes Kalshi, Polymarket Over Insider Trades

House Oversight and Government Reform Committee Chair James Comer on Friday sent letters to the chief executives of prediction market platforms Kalshi and Polymarket seeking documents and communications as part of an inquiry into insider trading. The letters set a June 5 deadline for the companies to produce records on identity verification, geographic limits and unusual-trade detection.

The committee opened a formal probe into trades tied to political events and potential government actions. The letters request policies, procedures, system logs and internal communications that would show how each platform prevents and responds to trades based on nonpublic information. The committee also asked for records related to flagged or blocked accounts, transaction logs and internal market-integrity reports.

Comer wrote that the review aims to determine how widespread insider trading has been on prediction markets and to gather evidence that could support legislation to bar members of Congress, administration officials and government employees from trading on those platforms.

The inquiry follows several documented incidents and recent policy changes at both firms. In April, a U.S. service member was arrested after authorities allege he used nonpublic information about the ouster of Venezuelan leader Nicolás Maduro to win about $400,000 on a prediction market. A separate review of trade records identified more than 80 users whose wagers reviewers described as suspicious, including trades placed hours before reported U.S. and Israeli strikes on Iran.

Kalshi paused accounts for three congressional candidates last month after those candidates placed bets on their own races, a violation of the platform’s rules. Kalshi operates under Commodity Futures Trading Commission regulation in New York and does not permit anonymous trading.

Polymarket is licensed in Panama and runs its primary market outside U.S. regulatory oversight. The company operates a separate limited product that is regulated by the CFTC for domestic users. Polymarket engaged a blockchain analytics firm in late April to help detect insider trading and market manipulation as part of its effort to win broader U.S. regulatory approval.

Comer’s letters follow requests from several lawmakers who had asked the Oversight Committee to consider subpoenas for the platforms earlier this month. Lawmakers from both parties have introduced bills this Congress that would restrict or bar trades by people with access to nonpublic government information.

The committee did not provide additional details about the scope of the review beyond the items listed in the letters. The deadline for document production is June 5.