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 CEOs of Kalshi and Polymarket about efforts to prevent insider trading on their platforms.
The investigation into Comer is the latest in a series of congressional efforts to rein in the platforms.
“Internal records kept by prediction market platforms are the only means by which bad actors can be identified and determined 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 to Kalshi CEO Tarek Mansour on Friday.
“Therefore, the Committee requests documents and information to better understand how Polymarket enforces identity verification for domestic and international account holders, enforces geographic restrictions, and detects anomalous trading activity to prevent insider trading on its global platform,” Comer’s letter continues.
CNBC has contacted both Kalshi and Polymarket for comment.
Representative James Comer, a Republican from Kentucky and chairman of the House Oversight and Accountability Committee, speaks to members of the media before a closed-door deposition with Commerce Secretary Howard Lutnick on Wednesday, May 6, 2026, in Washington, D.C., U.S.
El Drago Bloomberg | getty images
Prediction markets like Kalashi and PolyMarkets have exploded in popularity and are coming under increasing scrutiny from federal and state lawmakers and regulators.. They allow users to bet on the outcome of specific events in a variety of sectors, including sports, elections, award shows and government functions.
Following a series of highly publicized bets on world and political events, Comer said in an appearance on CNBC, “There is now a concern that members of Congress, members of the president’s administration, any type of government employee, can use basic insider knowledge and make huge profits on anything related to government.”
“So we want to launch an investigation to not only see how widespread this is, but also to make the case that we need to pass some type of legislation,” Comer said. “And I think it wouldn’t be too much to say that members of Congress can’t participate in prediction markets, nor can government employees or people in the president’s administration.”
Kalshi is headquartered in New York City and is regulated by Commodity Futures Trading Commission. It does not allow users to place bets anonymously, which is a controversial feature of some other platforms, including Polymarket, which operate outside the US.
While 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 offering that is regulated by the CFTC, but its international operations are not overseen by US regulators.
Both companies announced earlier this year that they were strengthening their rules on insider trading after a number of questionable trades became public.
Last month, a US soldier was arrested for allegedly using insider information to bet on Polymarket about the ouster of former Venezuelan leader Nicolas Maduro in January, making nearly $400,000.
And according to a recent report, more than 80 Polymarket users have placed bets with suspicious features, including deals made just hours before the US and Israeli attacks in Iran. New York Times investigation.
“The rapid growth and mainstreaming of this platform, the cryptocurrency infrastructure, and the anonymity it offers users has created unintended structural conditions that bad actors – particularly individuals with national security clearances – can exploit,” Comer wrote to Coplan.
Meanwhile, Kalshi says it does not allow event contracts related to war or death. But many political candidates have been caught betting on their own caste on the stage. In April, Kalshi suspended three Congress candidates who had bid on his own candidacy. Comer cited those bets as well as the company’s expansion into more than 140 countries in his letter to Kalshi.
“The rapid global expansion of Kalashi’s platform raises questions about whether internationally placed event contracts are subject to the same identity verification and insider trading prohibitions as domestic event contracts,” Comer wrote.
Bipartisan members of Congress have introduced a flurry of bills this Congress to rein in prediction markets. Many deal specifically with the issue of insider trading, while others are broader and seek to root out other activities on the platform, including sports betting.
Comer’s test is as follows Letter from seven Democratic MPsLed by Representative Chris Pappas of New Hampshire, who called on the Oversight Committee chairman to subpoena the forums.
“The American public has a legitimate interest in knowing whether individuals entrusted with classified national security information have used that access for personal financial gain,” the Democratic lawmakers wrote on May 11.
In his letters, Comer requested documents and communications from both CEOs about how each company verifies identities, enforces geographic restrictions and detects unusual trading. Comer asked for all information sent by June 5th.
Disclosure: CNBC and Kalshi have a commercial relationship that includes client acquisition and minority investment.