The House Oversight Committee opened a formal investigation into Polymarket and Kalshi on May 22, 2026, demanding internal records from both platforms and signaling that federal employees with access to classified information may be exploiting prediction markets to generate substantial personal profits.

Rep. James Comer (R-KY), chair of the House Oversight and Government Reform Committee, sent letters to the CEOs of both platforms requesting documentation on identity verification procedures, geographic restriction policies, records of suspicious trades, and transaction records specifically related to Venezuela and the war in Iran. Comer gave the companies two weeks to comply.

"We want to not only launch investigations to how widespread this has been so far, but also to prove a case we have to pass some sort of legislation," Comer told CNBC's Squawk Box on Friday.

The case that prompted it

The clearest documented precedent sits at the center of the probe. In April 2026, the Department of Justice charged Gannon Ken Van Dyke, a U.S. Army Special Forces master sergeant, with using classified information about Operation Absolute Resolve — the U.S. military mission that captured Venezuelan President Nicolás Maduro — to place bets on Polymarket. Van Dyke allegedly staked approximately $33,034 and made more than $409,000 on markets including whether Maduro would be removed from office by January 31 and whether the U.S. would invade Venezuela. Prosecutors allege he was involved in the planning and execution of the operation from December 2025 through at least January 2026 and subsequently attempted to obscure the source of his proceeds.

Van Dyke has pleaded not guilty to charges including commodities fraud, wire fraud, and theft.

The Van Dyke case was not isolated. According to a letter sent to Comer by Rep. Chris Pappas (D-NH) in May 2026, a single trader achieved a 93 percent success rate on bets predicting unannounced U.S. and Israeli military operations against Iran, placing wagers hours before strikes in October 2024, June 2025, and February 2026 and netting nearly $1 million. A separate group of 38 accounts made more than $2 million on the February 28 strikes alone, with accounts preloaded with funds the preceding week. Israeli authorities have separately indicted two individuals, including a military reservist, for trading on Polymarket using classified information.

The enforcement asymmetry

The probe surfaces a structural problem the existing regulatory framework has not resolved: the two platforms operate under fundamentally different legal regimes.

Kalshi is a U.S.-regulated derivatives exchange operating under CFTC oversight. It is legally required to identify its users, monitor for suspicious activity, and comply with domestic enforcement orders. When the committee sends a records request, Kalshi has a straightforward obligation to respond.

Polymarket operates from Panama. Under the terms of a 2022 settlement with the CFTC — which included a $1.4 million civil penalty — Polymarket agreed to block U.S. users from its platform. The practical result is a platform where the most suspect trades, including some of the Iran-related bets cited in the Pappas letter, appear to have been placed on Polymarket Global, the offshore version of the site that U.S. persons are already nominally barred from accessing. Enforcing a congressional records request against a Panama-based, blockchain-native platform is a different exercise than enforcing one against a CFTC-registered exchange with a domestic address.

Roll Call reported that Comer's letter to Polymarket specifically asked how the company verifies user identities and what geographic restriction policies it has in place — questions that implicitly acknowledge the geoblocking problem.

A cascade of escalating action

The House Oversight probe is the latest in a sequence of legislative and regulatory responses that have accelerated since early 2026.

On April 22, Kalshi announced it had suspended and fined three political candidates — Mark Moran, an independent running in Virginia's U.S. Senate race; Ezekiel Enriquez, who ran in a Texas Republican House primary; and Matt Klein, a Democratic state senator running for a Minnesota House seat — for placing bets on the outcomes of their own campaigns. Each agreed to pay fines and accepted five-year suspensions from the platform.

Eight days later, on April 30, the U.S. Senate unanimously passed a rule barring senators and their staff from trading on prediction markets, effective immediately. The resolution was introduced by Sen. Bernie Moreno (R-OH). Both Kalshi CEO Tarek Mansour and the broader industry framed the Senate action as a positive step toward normalizing oversight. "This is a great step to increase trust in our markets by making it an industry standard," Mansour wrote on X.

Both Kalshi and Polymarket had also announced anti-insider-trading measures in March 2026, following CFTC guidance, before the Van Dyke arrest made the problem concrete.

Legislative trajectory

Comer's remarks suggest the investigation is structured as legislative groundwork, not just a compliance exercise. A House resolution that would extend the prediction market trading ban to House members and employees has been referred to the Oversight Committee alongside the Judiciary and Ethics panels.

The harder question — whether to bar executive branch officials and security-cleared government employees from participating in prediction markets — has no equivalent legislative vehicle yet. That is the gap Comer's probe appears designed to document. The argument is structural: classified information gives government employees a meaningful edge in any market where geopolitical or military events are the underlying. Prediction markets are the first instrument where that edge is directly monetizable without passing through a licensed broker or leaving a trail in regulated securities markets.

Kalshi, by virtue of its CFTC registration, can be audited, fined, and compelled. Polymarket's Panama structure and blockchain-native settlement layer complicate that calculus significantly, though the CFTC has demonstrated it can reach offshore prediction markets when the legal predicate is clear enough — as the 2022 settlement showed. Whether the classified-information angle clears that bar is a question the probe is designed to answer.

The platforms have two weeks to respond to Comer's letters.