Comer Launches Investigation Into Insider Trading on Prediction Market Platforms

Requests documents and information from Polymarket and Kalshi to better understand how the platforms detect anomalous trading activity to prevent insider trading

WASHINGTON—House Committee on Oversight and Government Reform Chairman James Comer (R-Ky.) today opened an investigation into how users of prediction market platforms Polymarket and Kalshi potentially are using nonpublic information to engage in insider trading. In letters to Polymarket Chief Executive Officer Shayne Coplan and Kalshi Chief Executive Officer Tarek Mansour, Chairman Comer requests documents and information from Polymarket and Kalshi to assess how the platforms verify the identities of domestic and foreign account holders, enforce geographic restrictions, and monitor suspicious trading activity to guard against insider trading.

“The Committee on Oversight and Government Reform is examining the use of online prediction market platforms by some users to conduct insider trading. Specifically, 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. Internal records held by prediction market platforms are the only means by which bad actors can be identified and to determine whether platforms are meeting their legal obligations. The Committee requests documents and information to better understand how [Polymarket and Kalshi] implements identity verification for domestic and international account holders, enforces geographic restrictions, and detects anomalous trading activity to prevent insider trading across its global platform,” wrote Chairman James Comer.

According to a recent New York Times investigation, more than 80 Polymarket users placed suspiciously timed bets, including wagers made hours before undisclosed U.S. and Israeli military operations against Iran, raising concerns that safeguards across prediction market platforms may be inadequate. In May 2025, gubernatorial candidate Kyle Langford placed a $200 wager on his own race through Kalshi, while three other politicians also reportedly bet on contests involving their own campaigns. Additionally, a federal indictment unsealed on April 24, 2026, alleges that U.S. Army Master Sergeant Gannon Ken Van Dyke used classified information about Operation Absolute Resolve—the operation that led to the capture of Venezuelan President Nicolás Maduro—to place wagers that generated more than $409,000 in profits.

“This growing pattern of insider trading activity on prediction market platforms indicates that Congressional action may be necessary,” concluded Chairman James Comer.

Read the letters here: