US senators from both parties demand Kalshi and Polymarket explain election contract manipulation risks, insider trading linked to $143 million in profits

Odaily: U.S. Democratic Senator Elizabeth Warren and Republican Senator John Curtis sent letters on October 28 to prediction market platforms Kalshi CEO Tarek Mansour and Polymarket CEO Shayne Copeland, demanding explanations of how they will prevent 2026 midterm election contracts from being improperly influenced.

The two senators said election event contracts have attracted widespread attention and are viewed by some observers as indicators of political momentum. They asked the platforms to explain how they prevent candidates, campaign team members, and other election officials with access to non-public information from participating in related trading.

The senators also questioned the platforms' claim that such contracts are financial products rather than traditional gambling, citing incidents including Kalshi user and California gubernatorial candidate Kyle Langford betting on his own campaign, and former Congressman George Santos allegedly betting on whether he would attend Trump's State of the Union address.

The two also mentioned that Polymarket election contracts were alleged to involve wash trading in 2024. Researchers found that traders with inside information on political events, such as the timing of Israel's attack on Iran, made a combined $143 million in profits on Polymarket between 2024 and 2026. Kalshi enforcement head Robert DeNault said the platform prohibits insider trading and market manipulation and proactively blocks candidates and campaign team members from trading; Polymarket did not respond. (Business Insider)