Senators Warren and Curtis Question Kalshi, Polymarket Over Election Insider Trading Concerns

Sens. Elizabeth Warren and John Curtis are demanding answers from Kalshi and Polymarket about the safeguards they use to prevent political insiders from profiting from election-related trading.

In a bipartisan letter, the senators gave the two prediction-market operators until Nov. 3, Election Day, to respond to seven questions concerning the integrity of their election contracts. The inquiry focuses on whether candidates, campaign officials and others with privileged information can trade on markets tied to races in which they have a direct interest.

The lawmakers’ concerns extend beyond the possibility of individual insiders placing bets. Their letter also points to suspected wash trading on Polymarket, a practice in which coordinated transactions may create a misleading impression of market activity or demand. Such activity can make a contract appear more actively traded than it really is and potentially distort the prices that other participants use as signals of electoral expectations.

The senators cited instances involving candidates who allegedly bet on their own races, placing renewed attention on the boundary between political participation and financial speculation. A candidate trading in a market linked to his or her own contest could possess information unavailable to ordinary participants, including private polling, campaign strategy or knowledge of organizational strength. Even if a transaction did not directly affect the outcome of an election, the appearance of a conflict could undermine confidence in the market.

Kalshi and Polymarket allow users to buy and sell contracts connected to future events. In election markets, the value of a contract generally reflects the market’s estimate of whether a particular candidate or outcome will occur. Supporters view such prices as a way to aggregate information and measure expectations. Critics argue that turning political outcomes into tradable instruments can create opportunities for manipulation, encourage speculation and raise questions about whether participants are trading on information they should not be able to exploit.

The Warren-Curtis letter places those concerns in the context of a rapidly expanding debate over prediction markets. Political contracts have attracted substantial public interest because they offer a continuously updated alternative to traditional polling. Unlike a survey, which records the views of a selected group at a particular moment, a prediction market changes as participants buy and sell positions. That dynamic has made election contracts a prominent source of political forecasts, while also increasing scrutiny of the companies operating them.

The senators’ request appears designed to force the firms to explain how their systems identify and restrict potentially improper trading. Their seven questions reportedly seek information about the companies’ policies for keeping insiders out of election markets, as well as the measures used to detect suspicious activity. The letter’s reference to candidates trading on their own contests suggests that the lawmakers want more than general assurances about compliance. They are pressing the firms to address whether existing rules are capable of dealing with participants who may have a personal stake in the result.

The allegation of wash trading raises a separate issue. Markets depend on the assumption that reported volume and price movements reflect genuine transactions between independent participants. If traders coordinate to buy and sell among themselves, the resulting activity could give others an inaccurate view of liquidity or sentiment. Determining whether trading is legitimate can be difficult, particularly in online markets where users may operate through pseudonymous accounts or where multiple accounts could be controlled by related parties.

For the platforms, the scrutiny comes with the challenge of balancing open participation against market integrity. Broad access can help bring in more information and liquidity, but it can also increase the risk that participants with undisclosed connections to a campaign or political organization will take positions. Stronger restrictions may reduce those risks while also limiting the number of people able to trade and potentially reducing the usefulness of the market.

The senators’ deadline falls on Election Day, adding urgency to the request. By seeking responses before voting concludes, Warren and Curtis are drawing attention to the possibility that trading activity could influence public perceptions during the most sensitive stage of a campaign. A market price that is widely reported as an indicator of a candidate’s prospects can shape coverage and voter expectations, even though it is not itself a vote or an official forecast.

The letter does not, by itself, establish that any particular candidate improperly traded or that Polymarket engaged in wash trading. Instead, it raises questions about the companies’ procedures and asks them to account for how they police their markets. The distinction is significant: suspicious activity may warrant investigation, but allegations alone do not demonstrate that a rule was broken.

Kalshi and Polymarket now face pressure to provide detailed explanations of their controls, surveillance practices and treatment of politically connected traders. Their responses could add to the broader discussion over whether election prediction markets should be treated primarily as financial venues, forecasting tools or a distinct category requiring tailored oversight. As political contracts continue to attract attention, the ability of these platforms to show that their prices are generated by fair and transparent participation will remain central to their credibility.