Top prediction markets Kalshi and Polymarket will be undergoing an investigation in the U.S. for allegations of insider trading on their platforms. James Comer, the Chairperson of the House Oversight and Government Reform Committee announced the initiation of this probe on Friday.
The investigation is aimed at checking if Kalshi and Polymarket allow traders to use nonpublic information to engage with live trades.
Letters informing the platforms about the launch of the probe have been sent to Shayne Coplan and Tarek Mansour, the CEOs of Polymarket and Kalshi respectively, said an official statement by the House Oversight Committee. The letters have requested data and documents from the prediction markets outlining the ways they keep an eye for suspicious trading activities to curb insider trading.
“Specifically, we are examining the adequacy of company safeguards to prevent access to offshore sites to circumvent compliance with applicable U.S. federal regulations governing prediction market platforms,” said Comer. “Internal records held by prediction market platforms are the only means by which bad actors can be identified and to determine whether platforms are meeting their legal obligations.”
Source: House Republican
The development comes just four days after The New York Times published a detailed investigative report that claimed that 80 Polymarket users had suspiciously placed accurate bets just hours before the U.S. and Israel launched military operations against Iran on March 1.
The NYT report highlighted that a web of related accounts had hit a near-impossible win rate by perfectly timing volatile event contracts before they were made public. It raised red flags around the systemic vulnerabilities of these prediction markets, suggesting that individuals with high-level access to classified government intelligence were actively misusing the platform.
The House Oversight Committee also mentioned this NYT report in its statement.
“In May 2025, gubernatorial candidate Kyle Langford placed a $200 wager on his own race through Kalshi, while three other politicians also reportedly bet on contests involving their own campaigns. This growing pattern of insider trading activity on prediction market platforms indicates that Congressional action may be necessary,” Comer noted.
It is noteworthy that in February 2026, Kalshi’s internal disciplinary committee fined Langford and banned him for five years for that exact trade.
The NYT report is not the first time these allegations have been made.
Earlier in April, a resolution to prohibit trading in prediction markets by Senate members and staff was unanimously approved by the U.S. Senate. At the time, Polymarket and Kalshi, both had welcomed the decision.
Polymarket also unveiled an on-chain market integrity monitoring solution in April, looking to identify cases of insider trading and manipulation within its ecosystem.
For now, more details on the timeline of the investigation remain undisclosed. Neither Polymarket nor Kalshi have responded to the order as yet.