House Oversight Committee Opens Insider Trading Probe Into Prediction Markets

The House Oversight Committee announced Friday that it has opened an investigation into prediction-market platforms Kalshi and Polymarket over possible insider trading by users. Rep. James Comer, the panel's chairman, sent letters to the companies' chief executives requesting internal documents on how the platforms detect and prevent trading on nonpublic information.

The letters ask for details on identity-verification procedures for domestic and international accounts and on any investigations the firms have conducted into suspicious trading. Comer told CNBC that lawmakers are concerned government employees could use classified or nonpublic information to place profitable bets on policy and national-security events.

A data-analytics review cited in a recent 60 Minutes report identified nine Polymarket accounts that collectively earned $2.4 million by correctly predicting dates of key developments in the Iran conflict. In April, federal prosecutors charged a U.S. special forces soldier with using confidential government information to bet on the removal of former Venezuelan leader Nicolás Maduro, a wager that reportedly yielded more than $400,000.

A Polymarket spokesperson said the company maintains a comprehensive market-integrity framework. Kalshi spokesperson Elisabeth Diana told CBS News that the firm has implemented comprehensive safeguards against insider trading. Both platforms have recently tightened rules: Kalshi now bars members of Congress from opening accounts and has fined and suspended three congressional candidates; Polymarket adopted a March policy prohibiting traders who hold positions of authority from betting on events they could influence.