Warren and Curtis press Kalshi and Polymarket on election-market safeguards
Senators Elizabeth Warren and John Curtis are seeking details from Kalshi and Polymarket on how the platforms prevent insider trading and manipulation in election markets. Their concern extends beyond bettors: the contracts are widely covered and can be treated as signals of political momentum.2
TL;DR
- The inquiry puts the burden on both platforms to explain how their monitoring identifies trades using private election information and market manipulation.2
- The stakes include the public signal these contracts can send: the Senate-favorite contract strongly favors Democrats as the listed favorite, but it does not measure the likelihood of an election victory.2M1
Still to come
- The senators requested responses by Election Day, Nov. 3. The replies could clarify what safeguards the platforms say they use to detect improper election trading and how they assess their effectiveness.
In a letter sent ahead of the Nov. 3 midterms, Warren, a Democrat, and Curtis, a Republican, asked the companies about safeguards against trades based on material nonpublic information and other improper activity. They said election-contract prices receive prominent coverage and are treated by some observers as indicators of political momentum, raising questions about the information voters encounter.2
The senators cited cases of candidates betting on their own races and apparent trading-volume manipulation on Polymarket. Business Insider reported that California gubernatorial candidate Kyle Langford wagered on his own race in February 2026 and that Kalshi suspended him. The senators argue that identifying individual cases does not establish that platforms are catching similar activity more broadly.12
Kalshi’s head of enforcement told Business Insider that the platform prohibits insider trading and manipulation and blocks candidates and campaign staff from trading. He also said Kalshi’s markets had been largely nonreactive to fake information or attempts to distort candidate odds. Those claims underscore the question the senators are pressing: what evidence shows that the controls work, rather than merely that some violations have been detected?1
A separate contract observed on Nov. 2 priced the Democratic Party outcome at 99.9 cents for which party would have higher Senate-control odds in an 11 p.m. ET snapshot. That is an overwhelming expectation that Democrats would be listed as the favorite, not a 99.9% forecast that they will win the Senate. The distinction matters because the senators’ concern is partly about election-market odds being read as political momentum.2M1
Sources
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Senators want Kalshi and Polymarket to prove election odds aren't tainted ahead of the midterm vote · Business Insider · Nov 2
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Warren, Curtis Probe Kalshi and Polymarket on Improper Election-Related Trading · U.S. Senate Committee on Banking
AI-generated from the linked reporting and prediction-market data. Market prices reflect traders’ expectations and can change.