- Elizabeth Warren and John Curtis want Kalshi and Polymarket to report suspected election-trading violations stopped before trades and found afterward by Nov. 3.
- The letter also asks how many suspected cases each company sent to the CFTC or to police since Jan. 1.
- The letter cites candidates who traded on races they were running in on Kalshi and apparent volume manipulation on Polymarket.
- Kalshi says it blocks candidates and campaign staff from trading, and Polymarket told NPR it has investigated “dozens” of midterm bets.
WASHINGTON – Sens. Elizabeth Warren, D-Mass., and John Curtis, R-Utah, put seven questions to Kalshi and Polymarket about how their election trading safeguards perform, including how many suspected violations were stopped before trades occurred, with written answers due Nov. 3.
The senators’ Oct. 28 letter is addressed to Tarek Mansour, Kalshi’s chief executive, and Shayne Coplan, chief executive of Blockratize Inc., which does business as Polymarket. Warren is the top Democrat on the Senate Banking Committee.
The letter follows the Senate’s April 30 adoption of a prediction market insider trading ban that applies to senators and Senate staff.
The senators wrote that identifying isolated instances of improper trading “does not demonstrate that these markets are adequately protected.” The request splits each company’s record into suspected violations stopped before a trade and those identified after one.
On Kalshi, the letter points to a 2025 case and three April 2026 cases of candidates who traded on their own contests; on Polymarket, it points to trading patterns that researchers said looked like artificial volume. Both companies also list sports event contracts in states with legal sports betting, but the letter concerns election contracts.
Company Responses
Robert DeNault, Kalshi’s head of enforcement, told The Hill the company “proactively blocks candidates and campaign staff from trading to protect market integrity.” Polymarket did not immediately respond to The Hill’s request for comment on the letter.
Shana Bautista, Polymarket’s head of global intelligence and investigations, told NPR on Oct. 27 that the company has investigated “dozens” of bets tied to the midterm elections.
The Nov. 3 deadline falls on the day of the midterm elections.
