“The identification of isolated instances of improper trading does not demonstrate that these markets are adequately protected,” they wrote.
The letter asks how the companies keep candidates, campaign staff, election officials, pollsters and others with access to material nonpublic information from trading on election contracts. It also seeks details on how they identify trading based on confidential campaign information or unreleased polls, and prevent restricted traders from using third parties or affiliated accounts.
On manipulation, the senators want measures to detect wash trading, coordinated trading and activity that could artificially influence prices or reported volumes. They ask for supporting evidence that misconduct is not going undetected, whether surveillance systems have undergone independent evaluations, and what additional safeguards will be introduced before the elections.
A Test of Surveillance Claims
The request follows Polymarket’s Oct. 27 announcement describing election-specific surveillance across its U.S. and international platforms. The company said investigators combine automated alerts with reviews of trading, account and funding links, onchain records and publicly available information.
Polymarket said its teams also search historical trading data for activity existing detections may miss. Substantiated violations can lead to restrictions, disciplinary or legal action, or referrals to regulators and law enforcement, according to the announcement, which preceded the senators’ letter.
The company had already selected Chainalysis to help monitor trading and enforce platform rules in April, as The Defiant previously reported.
The senators also ask how both platforms prevent election-market contracts from being conflated with traditional polling, including what disclosures or controls they require when information about those contracts is published.
