House Oversight Committee chair Rep. James Comer launches an investigation into whether prediction markets Kalshi and Polymarket have safeguards to prevent insider trading. Multiple outlets report that Comer sends letters to the companies’ chief executives requesting documents and information related to potential insider trading concerns, including how the platforms monitor, detect, or restrict trading that could be informed by nonpublic information. The inquiry also focuses on market activity tied to war-related topics, according to the reporting. The outlets say the committee sets a document deadline of June 5 for the companies to respond. The investigation is framed as an effort by House Republicans to understand the rules, compliance processes, and controls that the companies use to prevent insider trading. The reports do not provide details of any specific alleged violation or wrongdoing by either company, but they indicate the committee is seeking information about the internal mechanisms that govern trading and integrity on these platforms.