[US Senators from Both Parties Demand Kalshi and Polymarket Explain Election Contract Manipulation Risks; Related Insider Trading Profits $143 Million] Odaily reports that US Democratic Senator Elizabeth Warren and Republican Senator John Curtis sent letters on October 28th to Tarek Mansour, CEO of prediction market platform Kalshi, and Shayne Copeland, CEO of Polymarket, demanding explanations on how to prevent improper influence on 2026 midterm election contracts. The two senators stated that election contracts receive widespread attention and are seen by some observers as an indicator of political momentum. They demanded that the platforms explain how they prevent candidates, campaign members, and other election officials with access to non-public information from participating in related transactions. The senators also questioned the platforms' definition of these contracts as financial products, distinguishing them from traditional gambling, and cited incidents such as Kalshi user Kyle Langford betting on his own election campaign, and former Congressman George Santos allegedly betting on whether he would attend Trump's State of the Union address. The two senators also mentioned allegations of wash trading in Polymarket's election contracts in 2024. Researchers have found that traders with inside information on political events such as the timing of Israel's attack on Iran profited a total of $143 million on Polymarket between 2024 and 2026. Robert DeNault, head of enforcement at Kalshi, stated that the platform prohibits insider trading and market manipulation and proactively prevents trading by candidates and campaign members; Polymarket did not respond to requests for comment. (Business Insider)