House Oversight Committee Chair Comer Opens Investigation Into Prediction-Market Insider Trading

By Nicholas G. Miller

James Comer, the Republican chair of the House Oversight Committee, opened an investigation into how users of Kalshi and Polymarket are using insider information to make trades on the prediction-market platforms.

Comer sent letters Friday to Polymarket Chief Executive Officer Shayne Coplan and Kalshi Chief Executive Officer Tarek Mansour requesting documents and information to assess how the platforms verify the users' identities, enforce geographic restrictions and monitor suspicious trading activity.

"We are examining the adequacy of company safeguards to prevent access to offshore sites to circumvent compliance with applicable U.S. federal regulations governing prediction market platforms," Comer said.

In a statement, Kalshi said "as a U.S.-regulated exchange, we are proud of our comprehensive protections against insider trading."

"We look forward to engaging with the Committee and its members about the systems and processes that we have spent years building," Kalshi added.

Representatives for Polymarket didn't immediately respond to requests for comment.

The Wall Street Journal previously reported that authorities have issued a number of information requests to Kalshi and Polymarket in recent months, with many focused on wagers tied to political events or military operations in Iran and Venezuela.

Last month, a U.S. special forces soldier, who allegedly bet on the capture of Venezuela's then-President Nicolás Maduro, was arrested.

"This growing pattern of insider trading activity on prediction market platforms indicates that Congressional action may be necessary," Comer said.

Write to Nicholas G. Miller at nicholas.miller@wsj.com

(END) Dow Jones Newswires

May 22, 2026 12:09 ET (16:09 GMT)