A committee led by Senator Elizabeth Warren is probing Kalshi and Polymarket ahead of the midterm elections.
Photo 1: Daniel Heuer/Bloomberg via Getty Images; Photo 2: Michael M. Santiago/Getty Images
Sen. Elizabeth Warren and Sen. John Curtis want answers about midterm odds from prediction markets.
Warren, a Democrat, and Curtis, a Republican, are “troubled” by election-related predictions.
In a letter to Kalshi and Polymarket, they say the platforms need more oversight of election betting.
Prediction markets are flashing red, white and blue as traders rush to wager on the 2026 midterms, but senators from both parties want to see proof odds aren’t being manipulated ahead of the vote.
In a letter to Kalshi CEO Tarek Mansour and Polymarket CEO Shayne Copeland, Massachusetts Democrat Elizabeth Warren and Utah Republican John Curtis asked for answers on what both platforms are doing to ensure the midterm odds haven’t been influenced unfairly.
“We are particularly troubled by election-related event contracts,” the senators wrote. “Event contracts tied to elections receive prominent coverage and are treated by some observers as indicators of political momentum.”
Sent on October 28, the letter to the platforms laid out the senators’ concerns regarding the potential for users to make election-related bets based on information that isn’t publicly available, as well as other kinds of trading behavior that could be considered market manipulation.
The senators also challenged the prediction markets’ narrative that the contracts users can trade are financial products and that are different from traditional gambling.
They cited Kalshi’s history as an example of why further scrutiny on election-related polls is needed, highlighting past instances of candidates using the platform to bet on their own victories, including a California gubernatorial race in February 2026 in which candidate Kyle Langford wagered on his own race.
“These examples raise critical questions about how many election-related transactions have escaped detection, including trades by people not identifiable from campaign filings,” the letter stated.
Kalshi suspended Langford, but he’s not the only politician accused of using prediction markets illicitly. Former Congressman George Santos is facing a federal probe after allegedly betting on Kalshi if he would attend President Trump’s State of the Union address.
Warren and Curtis highlighted similar instances involving Polymarket, noting 2024 allegations of wash trading in election-related contracts. The term refers to artificially inflating the trading volume of a security by quickly buying and selling, a practice that’s prohibited in other regulated markets.
More recently, researchers have found evidence that traders with inside information about political events, such as the timing of Israeli strike against Iran, netted a collective $143 million on Polymarket between 2024 and 2026.
Kalshi has said that it bans insider trading, a position it maintained recently after the Roosevelt Institute, a nonpartisan think tank, published an analysis claiming that the platform gave professional traders an unfair advantage over regular users.
Warren and Curtis appear remain unconvinced, and their letter includes a list of questions for Mansour and Coplan, including what steps they’ve taken to ensure that current candidates, their staff members, or other election officials with nonpublic information, aren’t placing bets on current races and how they will determine if a bettor has inside information.
“Kalshi prohibits insider trading and market manipulation and proactively blocks candidates and campaign staff from trading to protect market integrity,” Robert DeNault, head of enforcement at Kalshi, told Business Insider. “While fake polls have recently been promoted by major media outlets, our markets don’t lie—and have been largely non-reactive to fake information or attempts to distort the odds of candidates with big trades.”
Polymarket did not respond to a request for comment.
Read the original article on Business Insider
