Key Takeaways
- Sens. Warren and Curtis sent Kalshi and Polymarket seven questions on election insider trading, due Nov. 3.
- The senators want each firm’s count of suspected cases since Jan. 1 and how many they referred.
Seven Questions Due on Election Day
Sen. Elizabeth Warren, D-Mass., the ranking member of the Senate Banking Committee, and Sen. John Curtis, R-Utah, wrote to Kalshi CEO Tarek Mansour and Polymarket CEO Shayne Coplan in a letter dated Wednesday and released Thursday, asking how the companies stop insider trading and manipulation in election markets. They want written answers by Nov. 3, the day of the midterm elections.
“We are particularly troubled by election-related event contracts,” the senators wrote, noting that the contracts receive prominent coverage and are treated by some observers as indicators of political momentum.
The seven questions ask how each company stops candidates, campaign staff, election officials, pollsters, and others with nonpublic information from trading, how it stops them from getting around trading bans through third parties or affiliated accounts, and how it detects wash trading and other manipulation.
The senators also asked how many suspected cases of insider trading or manipulation in election contracts each company has identified since Jan. 1, how many were stopped before the trades went through rather than found afterward, and how many were referred to the Commodity Futures Trading Commission (CFTC) or law enforcement. They asked whether the companies’ surveillance systems have been independently evaluated, what safeguards will be added before the elections, and how the companies keep election contracts from being confused with polling.
The letter points to cases on Kalshi in which candidates traded on their own races, starting with a 2025 incident the CFTC described in a February advisory. According to the advisory, social media videos in May 2025 appeared to show a candidate trading on a contract tied to his own candidacy, and Kalshi fined the candidate and suspended him for five years. Kalshi disclosed three more such cases in April.
“These examples raise critical questions about how many election-related transactions have escaped detection,” the senators wrote. Separately, they cited NPR reporting on campaign staffers trading on internal polling before its release.
On Polymarket, the letter cites a 2024 Fortune report in which one blockchain analysis firm estimated that roughly one-third of the presidential election market’s trading volume was likely affected by wash trading. It also cites Wired’s finding this month of more than $600 million in trading on Polymarket election contracts involving Ethiopia and Romania. The outlet reported that the Ethiopian market kept trading for months after the vote, and Polymarket had blocked the accounts involved in response.
“The identification of isolated instances of improper trading does not demonstrate that these markets are adequately protected,” the senators wrote, adding that they remain skeptical the companies can police the contracts effectively.
Kalshi Head of Enforcement Robert DeNault told The Hill that “Kalshi prohibits insider trading and market manipulation and proactively blocks candidates and campaign staff from trading to protect market integrity.” A Kalshi source told the outlet that the company uses Federal Election Commission payroll data to block candidates and staffers, and has formed an independent market integrity committee. Polymarket did not immediately respond to The Hill’s request for comment.
Polymarket has investigated dozens of bets tied to the midterms, NPR reported on Oct. 27, with at least two cases referred to the CFTC, according to a person familiar with the investigations. This week, Polymarket is also reviewing dozens of newly created wallets that bet on Benjamin Netanyahu shortly before polls closed in Israel’s election on Tuesday, Bloomberg reported.
The letter is dated the same day Curtis’s home state of Utah filed criminal charges against Kalshi and its co-founders over sports bets. Curtis has backed a bipartisan bill with Sen. Adam Schiff, D-Calif., that would bar CFTC-registered platforms from offering sports contracts, while Warren co-introduced the STOP Corrupt Bets Act in March, part of a broader Democratic push to ban election and sports contracts.
