Blumenthal Presses Polymarket CEO Over Suspicious Bets

Sen. Richard Blumenthal sent a letter to Polymarket founder and CEO Shayne Coplan last week, requesting an explanation by April 24 for large anonymous trades placed shortly before classified U.S. military actions.

Blumenthal cited reporting that three Polymarket accounts collectively earned more than $600,000 by correctly predicting the timing of a U.S. pause in strikes against Iran. Those positions were opened weeks earlier at low odds and were cashed out after the public announcement. He said those accounts, which later changed their handles, were among six that together made about $1.2 million betting the United States would attack Iran by Feb. 28.

The senator identified other high-value trades timed near military events. One trader reportedly profited more than $400,000 by wagering on the imminent removal of Venezuelan President Nicolás Maduro less than five hours before a U.S. intervention. Another account cleared more than $550,000 within two hours of airstrikes that killed Iran’s supreme leader, according to the material cited in the letter. Authorities in Israel arrested several people in February on suspicion of using classified military information to place bets on the platform.

The White House Management Office issued a staff-wide reminder on March 24 that using nonpublic government information for personal financial gain is prohibited. That notice followed a presidential announcement pausing strikes against Iran. In the 15 minutes before that announcement, traders moved more than $760 million in oil futures, with heavy activity concentrated in a two-minute window. The White House confirmed the staff guidance and a spokesperson reiterated that government employees must not use nonpublic information for financial benefit.

In his letter, Blumenthal posed five specific questions to Polymarket: why the platform still hosts markets on military action and heads of state; what internal investigations have been opened into suspected insider-driven trades tied to Venezuela and Iran; whether Polymarket has reported suspicious accounts to federal authorities; what identity verification the platform requires of users; and why U.S. users can bypass geographic restrictions using virtual private networks.

Blumenthal wrote, “Polymarket has become an illicit market to sell & exploit national security secrets unlike any in history,” and added, “The financial incentive to abuse trust apparently worked.” Coplan earlier described the platform as creating a financial incentive for people to divulge information to the market.

Polymarket updated its rules last month to explicitly ban insider trading and bar users from trading on contracts when they possess material nonpublic information or the power to influence an outcome. The company has previously defended its operation as a public prediction market.

Blumenthal introduced the Prediction Market Security and Integrity Act, which would increase regulatory controls over prediction markets and restore some oversight to states. He has also joined another senator in urging a ban on contracts tied to war or military action.

Polymarket has been asked to respond publicly and to provide details of any internal reviews and compliance steps by the April 24 deadline.