Members of the US House Committee on Oversight and Government Reform have launched an investigation into cryptocurrency prediction platforms Polymarket and Kalshi over concerns tied to insider trading and politically sensitive bets.
Committee Chairman James Comer sent letters to Polymarket CEO Shayne Coplan and Kalshi CEO Tarek Mansour requesting internal documents related to how both companies monitor and prevent insider trading activity.
Comer said lawmakers are increasingly concerned that government officials or politically connected individuals could be using nonpublic information to profit from prediction markets.
The investigation follows reports that users placed large bets related to Israeli military action against Iran, Donald Trump’s ceasefire announcement, and several congressional election events before key developments became public.
Congress Pressures Prediction Markets Over Insider Trading Risks
Prediction markets have grown rapidly in recent years, allowing users to trade contracts tied to political events, geopolitical conflicts, and economic outcomes. Supporters argue these platforms improve forecasting accuracy, while critics warn they could become vulnerable to insider abuse.
Both Polymarket and Kalshi have already introduced measures aimed at reducing manipulation risks.
In March, Polymarket updated its policies around suspicious trading activity and market integrity. Kalshi later blocked three US politicians from betting on the outcomes of their own elections.
Representatives from both companies responded publicly after receiving Congressional letters.
A Polymarket spokesperson said the platform maintains a “comprehensive market integrity system” and plans to cooperate with lawmakers during the investigation.
Kalshi also defended its compliance framework, stating that the company has implemented “comprehensive insider trading protections” and intends to engage with Congress.
DOJ Case Adds Pressure to the Industry
The Congressional investigation arrives as the US Department of Justice continues pursuing a separate criminal case tied to prediction market trading.
In April, federal prosecutors charged Staff Sergeant Gannon Ken Van Dyke, who allegedly used classified information connected to an operation involving Venezuelan President Nicolás Maduro to trade contracts on Polymarket.
According to investigators, Van Dyke earned more than $400,000 by using confidential government information before the events became public.
He later pleaded guilty to charges tied to fraud and the unlawful use of confidential government information for personal gain.
The court released Van Dyke on $250,000 bail with travel restrictions limiting him to North Carolina, California, and New York while the case continues.
Why the Investigation Could Reshape Prediction Markets
The investigation highlights a growing legal and ethical debate surrounding prediction markets and insider information.
Unlike traditional financial markets, prediction platforms are designed to aggregate information from participants who may hold unique insights into real-world events. Regulators now face a difficult question: where does legitimate informed trading end and illegal insider trading begin?
Legal experts believe the Van Dyke case could become a major precedent for how US authorities regulate event-based trading markets in the future.
Congress is now seeking internal records from both Polymarket and Kalshi to evaluate whether their safeguards are strong enough to prevent misuse of sensitive information.
The outcome of both the Congressional investigation and the DOJ case could significantly influence how prediction markets operate under future US regulation.
