House Oversight chair launches insider trading probe into Polymarket and Kalshi
House Oversight and Government Reform Committee Chair James Comer, R-Kentucky, has opened a formal congressional investigation into Polymarket and Kalshi on insider trading concerns, the two largest US prediction market platforms in the event contracts space. The probe was announced May 26. Specific allegations, scope, and hearing timeline remain unspecified in available excerpts. The investigation follows separate demands from Comer that the two platforms' CEOs produce surveillance records, and comes as the same conduct is under review by DOJ-CFTC and four state enforcement proceedings. It also coincides with the CFTC's suspension of officials who raised concerns on Polymarket, Crypto.com, and Gemini, and with Indonesia blocking Polymarket after users bet on President Prabowo's early exit.
Kalshi and Polymarket must now defend against simultaneous congressional, DOJ-CFTC, and four state proceedings while the CFTC's own neutrality is compromised by whistleblower suspensions. Any disclosure gap between Comer's committee and those parallel tracks becomes real-time evidence against the platforms.
The probe is the third congressional action targeting Kalshi and Polymarket in two days, after Comer's paired record demands, and comes alongside CFTC suspension of officials who raised concerns on those same platforms — placing both firms at the center of a four-front fight spanning Congress, DOJ, state regulators, and international blocking orders.