House Committee on Oversight and Government Reform Chairman James Comer announced on May 22 an investigation into possible insider trading by users of the prediction market platforms Polymarket and Kalshi. Comer sent letters to Shayne Coplan, Chief Executive Officer of Polymarket, and Tarek Mansour, Chief Executive Officer of Kalshi, requesting documents and information about how the companies verify user identities, enforce geographic restrictions, and monitor for suspicious trading activity.
The investigation aims to assess whether current safeguards are sufficient to prevent users from exploiting nonpublic information for financial gain. The committee is also looking at whether some individuals are using offshore sites to bypass U.S. regulations governing prediction markets.
“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.
A recent New York Times investigation found that more than 80 Polymarket users placed bets that appeared suspiciously timed around undisclosed military operations involving the United States and Israel against Iran. In another case from May 2025, gubernatorial candidate Kyle Langford reportedly wagered $200 on his own election through Kalshi; three other politicians were also said to have bet on races in which they were candidates. Furthermore, a federal indictment unsealed in April alleges that U.S. Army Master Sergeant Gannon Ken Van Dyke used classified details about Operation Absolute Resolve—the mission leading to Venezuelan President Nicolás Maduro’s capture—to place wagers generating over $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.
The committee has made public its requests for further documentation from both companies as it continues its inquiry.
