US Senators Elizabeth Warren and John Curtis have raised concerns over potential insider trading and market manipulation on election-related prediction markets, questioning whether operators Kalshi and Polymarket can adequately detect and prevent improper trading.
In a bipartisan letter to Kalshi CEO Tarek Mansour and Polymarket CEO Shayne Coplan, the lawmakers demanded details of existing safeguards, previous enforcement actions, and suspected violations referred to the Commodity Futures Trading Commission’s (CFTC) rules.
The scrutiny comes as Mansour and other prediction market executives face separate criminal charges in Utah, where Attorney General Derek Brown has accused them of illegally profiting from promoting and offering online gambling. The defendants face 13 felony counts and one misdemeanor.
The senators’ concerns center on election-related event contracts, which allow traders to speculate on yes-or-no outcomes, including electoral results. Their letter referenced alleged manipulation on Polymarket during the 2024 presidential election, reportedly affecting “roughly one-third of the presidential market’s trading volume,” according to Fortune.
It also highlighted incidents involving political candidates trading on their own electoral prospects through Kalshi in 2025 and 2026. “These examples raise critical questions about how many election-related transactions have escaped detection,” the lawmakers wrote.
One case involved former Virginia Democratic Senate candidate Mark Moran, who told the Indian Gaming Association’s New Normal podcast that Kalshi allowed him to purchase a $100 contract concerning his campaign after adding his name to a prospective candidates market in November 2025.
“I had to register with my own driver’s license, put my name to this, yet I was allowed to then bet,” Moran said. “Why is this happening?” According to Kalshi’s disciplinary notice, Moran placed two trades on January 27, 2026, and subsequently promoted the market on social media, violating exchange Rule 5.17(z).
Moran acknowledged the violations during a subsequent discussion with Kalshi’s compliance and legal departments but declined settlement and stopped responding to correspondence. He claimed Kalshi increased its proposed penalties from a one-year suspension and $800 fine to a five-year ban and $6,229.30 after he refused to issue a public statement.
The CFTC separately documented a 2025 incident involving a candidate trading on his own candidacy, which emerged through social media videos before Kalshi imposed penalties.
Responding to the scrutiny, Kalshi’s head of enforcement, Robert DeNault, told The Hill, “Kalshi prohibits insider trading and market manipulation and proactively blocks candidates and campaign staff from trading to protect market integrity.”
A company source said Kalshi uses Federal Election Commission payroll records to identify restricted traders and has established an independent market integrity committee. However, the senators sought explanations of safeguards extending beyond FEC filings, including measures targeting individuals possessing material nonpublic information.