Warren, Curtis Probe Kalshi and Polymarket on Improper Election-Related Trading

Warren, Curtis Probe Kalshi and Polymarket on Improper Election-Related Trading

Ahead of the 2026 midterm elections, Ranking Member Warren and Senator Curtis (R-UT) seek answers on whether prediction markets are doing enough to prevent insider trading and market manipulation on election-related markets.

"Given the significant financial incentives associated with election-related contracts, we…question whether the purported benefits of these markets justify the potential harm to the integrity of the information Americans rely on to understand our elections."

Text of Letter (PDF)

Washington, D.C. - U.S. Senator Elizabeth Warren (D-Mass.), Ranking Member of the Senate Banking, Housing, and Urban Affairs Committee, and Senator John Curtis (R-Utah), wrote to Kalshi CEO Tarek Monsour and Polymarket CEO Shayne Coplan, raising concerns about election-related prediction markets and requesting information about the companies' efforts to prevent insider trading, market manipulation, and wagers based on material nonpublic information.

"We are particularly troubled by election-related event contracts. Event contracts tied to elections receive prominent coverage and are treated by some observers as indicators of political momentum," wrote the bipartisan Senators. "There are also documented cases of candidates betting on their own races, which undermines the overall integrity of the American electoral process."

The letter cited several cases of political candidates trading on their own races on Kalshi's prediction market platform, as well as instances of what appeared to be significant trading volume manipulation on Polymarket - prompting serious questions about election integrity and the degree to which improper election-related transactions have remained undetected.

"A separate NPR investigation described campaign insiders who said they profited by trading before the release of polling information; NPR reported verifying at least one trade against prediction-market records," the Senators continued. "That concern is particularly acute as Election Day approaches, when confidential campaign decisions, internal polling, and election-administration information may have immediate financial value and the impact of election-related event contracts on the public's perception of races is maximally influential."

"We remain skeptical that your companies can sufficiently police these even contracts with effective scrutiny and meaningful accountability," the Senators concluded. "The identification of isolated instances of improper trading does not demonstrate that these markets are adequately protected. Instead, it raises serious questions about how much similar activity may be going undetected."

The Senators requested responses to their answers by Election Day, Tuesday, November 3rd.

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