US senators ask Kalshi and Polymarket about safeguarding election markets — The Hill
In the United States, Democratic Senator Elizabeth Warren and Republican Senator John Curtis asked the Kalshi and Polymarket platforms to provide information on measures to combat insider trading, market manipulation and betting based on material non-public information. The request concerns prediction markets related to the US midterm elections in November 2026, The Hill reports.
Concerns over election contracts
In a letter to Kalshi CEO Tarek Mansour and Polymarket CEO Shane Coplan, the senators drew attention to election-related event contracts. This type of asset allows users to trade depending on a “yes” or “no” answer to a specific question.
Warren and Curtis mentioned several cases in which candidates placed bets on their own races on Kalshi in 2025 and in April 2026. According to the senators, these examples raise questions about how many election-related transactions may have gone unnoticed.
The letter also cited a Fortune report on alleged market-manipulation tactics on Polymarket during the 2024 presidential election. According to that report, such actions may have involved around one-third of the trading volume in the platform’s presidential market.
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What data the senators requested
The lawmakers asked both companies to provide details on measures they have already taken to prevent potential insider trading by election campaigns and other individuals with access to material non-public information. They also asked which cases of election-related insider trading had been referred to the US Commodity Futures Trading Commission and what safeguards are currently in place.
A Kalshi representative said the platform proactively blocks candidates and campaign staff from trading in election markets, using staff payment data filed with the US Federal Election Commission. According to the representative, the company has also established an independent market integrity committee to counter potential insider trading.
Kalshi’s response and the Utah case
Kalshi’s head of compliance told The Hill that the company prohibits insider trading and market manipulation and blocks candidates and campaign employees to protect market integrity. Polymarket did not provide an immediate comment in response to the outlet’s request.
The senators’ letter came after Utah Attorney General Derek Brown brought criminal charges against Mansour and other prediction-market executives. According to the prosecution, they unlawfully profited from promoting and offering online gambling in the state. As The Hill reports, citing court documents, the case involves 13 felony counts and one lesser offense count.
