Congressional investigation is in response to recent cases of suspected “insider trading” on military action event contracts
US House Oversight and Government Reform Committee Chair James Comer has opened a formal congressional investigation into prediction market platforms Polymarket and Kalshi.
The intervention stems from growing concerns that government employees and others with access to classified information may be exploiting those platforms for financial gain.
Comer sent document-request letters to Polymarket CEO Shayne Coplan and Kalshi CEO Tarek Mansour, setting a June 5 deadline. The letters demanded records on identity verification procedures, geographic access restrictions, and internal systems for detecting unusual or suspiciously timed trades, as well as information on any prior referrals to government agencies.
Two specific incidents drove the probe. In April, a US Army soldier was charged with unlawful use of confidential information after allegedly purchasing contracts on a Polymarket market tied to Venezuelan President Nicolás Maduro’s removal from power, netting roughly $400,000 on an initial $33,000 trade.
Separately, a New York Times investigation identified more than 80 Polymarket accounts placing trades in the hours before US and Israeli military operations against Iran became public knowledge.
Comer described the current regulatory environment as erratic. He added that he may pursue legislation barring members of Congress, administration officials, and federal employees from using prediction markets altogether.
In recent months, both platforms have tightened internal rules. Kalshi fined and suspended three congressional candidates who had wagered on their own elections, and now bars sitting members of Congress from holding accounts.
Both companies said they welcomed the committee’s engagement and pointed to their existing compliance frameworks as evidence of responsible platform management.