The US House Oversight and Government Reform Committee has opened a formal investigation into potential insider trading on prediction market platforms Polymarket and Kalshi. Chairman Rep. James Comer (R-KY) is leading the inquiry, which zeroes in on trading patterns that appeared suspiciously well-timed around major geopolitical events.
What triggered the probe
The investigation, announced on May 22, 2026, was prompted by identifiable patterns of suspicious trades that appeared to correlate with significant geopolitical developments. Two events drew particular scrutiny: the Iran conflict and the alleged capture of Nicolás Maduro, former leader of Venezuela.
Comer has sent document requests to Polymarket CEO Shayne Coplan and Kalshi CEO Tarek Mansour. The requests cover user identity verification procedures, geographic restrictions on trading, internal detection systems for suspicious activity, and safeguards against the exploitation of nonpublic information.
Both platforms have until June 5, 2026 to respond.
