A letter from seven House Democrats was sent to House Oversight Chair James Comer on Monday that urged for subpoena power to dig into a number of suspiciously timed trades on prediction markets tied to U.S. military operations in Iran. In a growing effort to crackdown on prediction markets, this latest letter is yet another push from Congress to bring platforms like Polymarket and Kalshi under direct investigative scrutiny. The lawmakers cited a CNN report from March detailing how a single Polymarket trader raked in close to $1 million with a 93% success rate on wagers predicting unannounced U.S. and Israeli strikes against Iran. That trader placed bets hours before operations in October 2024, June 2025 and February 2026. A separate cluster of 38 accounts netted over $2 million on the February 28 strikes alone after being preloaded with funds the week prior. At least 50 newly created accounts also placed coordinated bets on a U.S.-Iran ceasefire on April 7, with some accounts opened just minutes before the announcement went public. The Van Dyke Arrest Set the Stage The letter directly references the April arrest of U.S. Army Master Sgt. Gannon Van Dyke , who was charged with using classified information about the Maduro capture mission to place bets on Polymarket. Israeli authorities have also indicted two individuals, including a military reservist, for placing Iran-related bets using classified intelligence. The Van Dyke case was just the start and it has given Congress a criminal precedent to point to. The Democrats are now referencing this case as a broader, systematic problem rather than an isolated issue within the prediction markets. Polymarket Global Is the Weak Link The platform that came under scrutiny in the letter was Polymarket Global, the offshore arm of Polymarket that is supposed to be inaccessible to Americans but appears to be easily bypassed via VPNs. The lawmakers wrote that some of the suspicious trades were placed on Polymarket Global specifically, and called out the platform’s failure to enforce meaningful identity verification or block U.S. users. Kalshi, by contrast, operates under CFTC regulation as a designated contract market and requires identity verification. The company has also taken steps to self-police, suspending and fining three political candidates earlier this year for insider trading on their own campaigns. Polymarket is still seeking full U.S. licensure after a Biden-era consent order forced it to geoblock American users, a restriction it partially lifted last November. From Self-Regulation to Subpoenas The escalation in tone from Congress is notable. Last month, the Senate unanimously voted to ban its own members from trading on prediction markets. The White House warned staff against using nonpublic information on financial markets in April. Several bipartisan bills targeting prediction market insider trading have been introduced since March. But the subpoena demand takes this a step further. Voluntary bans and self-imposed platform guardrails are one thing. Congressional subpoena authority is something else entirely and could force platforms to hand over trading data, account records and internal compliance logs. The lawmakers have asked Comer to outline the committee’s planned approach by May 22. Whether the Republican chair acts on the request remains to be seen, but the political pressure is building fast. Prediction markets spent a combined $975,000 on federal lobbying in 2025. They may need to spend a lot more in 2026. If you're reading this, you’re already ahead. Stay there with our newsletter .
