Sens. Warren, Curtis Press Kalshi and Polymarket on Insider Trading in Midterm Betting

Sen. Elizabeth Warren (D-Mass.) and Sen. John Curtis (R-Utah) are asking the country’s two largest prediction market companies to explain how they keep political insiders from betting on elections, days before the Nov. 3 midterms.

In a letter dated Oct. 28 to Kalshi CEO Tarek Mansour and Polymarket CEO Shayne Coplan, the senators said they were particularly troubled by markets tied to elections. They said those markets get prominent news coverage, are treated by some observers as a sign of political momentum, and may shape how voters see a race.

“There are also documented cases of candidates betting on their own races, which undermines the overall integrity of the American electoral process,” they wrote.

Warren is the top Democrat on the Senate Banking, Housing, and Urban Affairs Committee.

Prediction markets let users buy contracts tied to real-world outcomes, including who will win a given House, Senate, or governor’s race.

The senators pointed to Kalshi’s own enforcement record. The Commodity Futures Trading Commission, which regulates the company, described a 2025 case in which a candidate traded on his own candidacy.

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The activity came to light through videos posted on social media before Kalshi penalized and suspended him. In April, Kalshi disclosed that it had fined and suspended three more candidates for trading on their own races.

According to the senators, those cases raise the question of how many election trades went undetected, including trades by people who can’t be identified through campaign finance filings.

They asked both companies what they do to detect wash trading, in which the same trader or coordinated traders buy and sell to each other, and other coordinated activity that could artificially move a contract’s price or inflate its reported trading volume.

The senators said the risk grows as Election Day approaches, when internal polling, confidential campaign decisions, and information about how elections are run can carry immediate financial value.

They gave the companies until Nov. 3 to answer seven questions, including how many cases of suspected insider trading or market manipulation on election contracts each company has identified since Jan. 1, how many were stopped before a trade went through, and how many were referred to the CFTC or law enforcement. They also asked whether outside evaluators have reviewed the companies’ surveillance systems.

The senators said they remain skeptical that the companies “can effectively police their own platforms.”

Kalshi said in a statement to The Epoch Times on Thursday that it prohibits insider trading and market manipulation and proactively blocks candidates and campaign staff from trading.

“We know Congress is considering legislation that would make it a crime for campaign staff to trade on their own races, but we aren’t waiting for new laws,” Robert DeNault, Kalshi’s head of enforcement, said in the emailed statement.

DeNault said fake polls have recently been promoted by major media outlets, and that Kalshi’s markets have largely not reacted to false information or to large trades aimed at moving a candidate’s odds.

The company said it identifies candidates and campaign staff by checking Federal Election Commission payroll data against its identity-verified users and uses real-time surveillance to catch violations. Anyone caught faces disciplinary action from the exchange and referral to law enforcement, the company said.

Kalshi also pointed to an independent market integrity committee it formed and to its work with trading surveillance firm Solidus Labs and Daniel Taylor, director of the Wharton Forensic Analytics Lab. The company said it looks forward to showing Congress how it keeps insider trading off its platform.

A Polymarket spokesperson told The Epoch Times on Thursday that the company actively monitors election-related activity, using its Polygraph technology to help its global intelligence team flag trades that need a closer look.

“We work regularly with the DOJ and CFTC, referring suspicious traders, including any related to election markets and look forward to engaging with Senators Warren and Curtis to educate them on how our platform is a pioneer in transparency and market integrity,” the spokesperson said.