Rep. James Comer, R-Ky., chairman of the House Oversight and Government Reform Committee, announced Friday on CNBC’s “Squawk Box” that he is seeking information from the top executives of Kalshi and Polymarket about their efforts to prevent insider trading at their foundations.
Comer’s investigation is the latest in a series of congressional efforts to tighten platforms.
“Internal records maintained by prediction market platforms are the only way bad actors can be identified and determine whether the platforms are meeting their legal obligations,” Comer wrote in a letter sent Friday to Polymarket CEO Shayne Coplan and seen by CNBC. A similar letter, also seen by CNBC, was sent Friday to Kalshi CEO Tarek Mansour.
“Therefore, the Committee is requesting documents and information to better understand how Polymarket uses identity verification for domestic and international account holders, enforces geographic restrictions, and finds illegal trading activity to prevent insider trading worldwide,” Comer’s letter continued.
Elisabeth Diana, Kalshi’s head of communications, said in a statement that they “look forward to discussing with the Committee and its members the plans and procedures we have spent years building.”
“As a US regulated exchange we pride ourselves on our comprehensive protection against insider trading,” said Diana.
A Polymarket spokesperson said in an emailed statement that the company “maintains a comprehensive framework for market integrity. We look forward to engaging with Chairman Comer and the committee about how our platform is open to transparency.”
Representative James Comer, Republican of Kentucky and chairman of the House Oversight and Accountability Committee, speaks to members of the media before a closed-door hearing with Commerce Secretary Howard Lutnick, not pictured, in Washington, DC, US, Wednesday, May 6, 2026.
Al Drago Bloomberg | Getty Images
Prediction markets like Kalshi and Polymarket have exploded in popularity and drawn increasing scrutiny from state and federal lawmakers and regulators.. It allows users to bet on the outcome of certain events in a variety of areas, including sporting events, elections, award shows and government actions.
After a series of highly publicized bets on national and political events, Comer, in an appearance on CNBC, said “there is concern now that members of Congress, members of the presidential administration, any type of public servant, can use basic inside information and make a huge profit on anything related to government.”
“So we don’t just want to launch an investigation to see how much this has increased so far, but also to confirm the case that we should pass some kind of law,” said Comer. “And I think it would not be difficult to ask to say that members of Congress cannot participate in the prediction market, nor can government employees or people in the administration of the president.”
Kalshi is headquartered in New York City and is regulated by the Commodity Futures Trading Commission. It does not allow users to bet anonymously, a controversial feature on other platforms, including Polymarket, which operates outside the US.
Although Polymarket also has offices in the US, it is a blockchain-based platform operated by an entity licensed in Panama. It has a limited US product regulated by the CFTC, but its foreign operations are not overseen by US regulators.
Both companies announced earlier this year that they were tightening their rules on insider trading after a number of questionable public sales.
Last month, a US soldier was arrested for allegedly using insider information to make bets at Polymarket about the ouster of former Venezuelan leader Nicolás Maduro. in January, it receives about $400,000.
And more than 80 Polymarket users bet on suspicious features, including trades made hours before the US and Israeli strikes on Iran, according to a recent New York Times investigation.
“The rapid growth and widespread use of this platform, the infrastructure of cryptocurrency, and the anonymity it offers users may create unintended structural conditions that bad actors – especially people with national security clearances – can exploit,” Comer wrote for Coplan.
Kalshi, on the other hand, says that he does not allow contracts for events related to war or death. But many political candidates have been caught betting on their platform races. In April, Kalshi suspended three Congress candidates who were betting against him. Comer cited that bet in his letter to Kalshi and the company’s expansion into more than 140 countries.
“The rapid global expansion of the Kalshi platform raises questions about whether contracts for events placed around the world are subject to the same ownership guarantees and insider trading restrictions as contracts for domestic events,” Comer wrote.
Bipartisan members of Congress have introduced several bills this Congress to strengthen the prediction markets. Several deal directly with the issue of insider trading, while others are broader and seek to eliminate other activities on the platform, including sports betting.
Comer’s investigation follows a letter from seven Democratic lawmakers, led by Rep. Chris Pappas of New Hampshire, who called the chairman of the Security Committee to call the courts.
“The American public has a legitimate interest in knowing whether people who have been given national security information have used that access for financial gain,” the Democratic lawmakers wrote on May 11. “The committee’s investigation, enforced by subpoenas, will include internal records, the only way the people who made these trades can be identified and the question of whether these platforms can be answered.”
In his letters, Comer requested documents and communications from both senior officials about how each company verifies identities, enforces geographic restrictions and detects irregular transactions. Comer requested all of the information released on June 5.
Disclosure: CNBC and Kalshi have a commercial relationship that includes customer acquisition and a small investment.
