The U.S. House Speaker launched a congressional investigation into Kalshi and Polymarket for alleged insider trading.

On May 22, CNBC reported that James Comer, chairman of the U.S. House Oversight and Reform Committee, has launched an investigation into prediction market platforms Kalshi and Polymarket. He sent letters to the CEOs of both companies requesting internal documents concerning measures to prevent insider trading, identity verification, geographic restrictions, and monitoring of unusual transactions. Comer stated that internal records are the only way to identify accounts suspected of profiting from national security secrets, including military personnel and those with security clearances. The investigation specifically targets transactions related to election results and U.S. military actions against Iran and Venezuela. Previously, a U.S. soldier was arrested for allegedly profiting approximately $400,000 on Polymarket using intelligence related to regime change in Venezuela. Additionally, over 80 users were exposed for placing orders hours before U.S.-Israeli airstrikes on Iran. Several lawmakers have already introduced legislation to restrict prediction markets.