The House Oversight Committee is conducting an investigation into Kalshi and Polymarket amid concerns that some users may be exploiting non-public information to gain trading advantages on prediction market platforms.
House Oversight Chairman James Comer on Friday sent document requests to Polymarket’s Shayne Coplan and Kalshi’s Tarek Mansour. The committee said it is seeking records to assess how each platform verifies account holder identities, applies geographic restrictions and monitors for suspicious trading behavior.
Prediction markets allow users to place bets on the likelihood of various events and have seen increased activity over the past 18 months. Critics argue that a number of profitable wagers appear unusually precise, raising questions about whether they reflect inside knowledge rather than chance.
The committee cited a series of high-profile incidents in recent weeks. In April, a U.S. soldier was charged with using classified information about the timing of the capture of then-Venezuelan President Nicolás Maduro to generate more than $400,000 in gains trading on Polymarket. Polymarket said it identified a trader who used classified information and referred the case to the Justice Department.
Also in April, Kalshi disclosed that it suspended and fined three congressional candidates for engaging in political insider trading on markets tied to their own campaigns. Kalshi said it is committed to policing unfair or improper trading on its platform.
Referencing those incidents, Chairman Comer said, "this growing pattern of insider trading activity on prediction market platforms indicates that Congressional action may be necessary."
Concerns have intensified after reports of suspiciously timed trades ahead of President Donald Trump’s policy announcements. Lawmakers have noted unusual trading patterns and requested that regulators probe the activity.
The committee’s document requests aim to clarify current platform safeguards and the extent to which Kalshi and Polymarket detect and respond to potential misuse of non-public information. The inquiry comes amid broader questions about how emerging financial products and platforms should be overseen.