House Oversight Opens Insider Trading Probe Into Polymarket and Kalshi as Kalshi Debuts New Lobbying Arm

House Oversight Chair James Comer launched a probe into Polymarket and Kalshi citing suspicious trades on Iran and Venezuela. Kalshi unveiled a new lobby group hours later.

House Oversight and Government Reform Committee Chair James Comer (R-KY) opened a congressional investigation Friday into insider trading on prediction market platforms Polymarket and Kalshi, escalating bipartisan scrutiny that has been building for months.

Comer sent document-request letters to Polymarket CEO Shayne Coplan and Kalshi CEO Tarek Mansour, demanding records by June 5 on identity verification procedures, geographic restrictions, internal detection systems for suspicious activity, and safeguards against the exploitation of nonpublic information. Comer told CNBC he may pursue legislation barring members of Congress, administration officials, and federal employees from participating in prediction markets, framing the current environment as “the Wild West.”

This story is an excerpt from the Unchained Daily newsletter.

The probe cites two specific incidents.

In April, a U.S. Army soldier named Gannon Van Dyke was charged with unlawful use of confidential information after allegedly purchasing $33,000 worth of “yes” contracts on Polymarket’s “Maduro Out by January 31, 2026” market, netting roughly $400,000 when Nicolás Maduro was ousted as Venezuelan president.

Separately, a New York Times investigation found more than 80 Polymarket users placed suspicious trades, including wagers placed hours before U.S. and Israeli strikes on Iran. Kalshi previously suspended three congressional candidates in April after they bet on their own races, and Polymarket has touted internal compliance upgrades ahead of Friday’s announcement.

Both companies pushed back.

Kalshi said it “looks forward to engaging with the Committee and its members about the systems and processes that we have spent years building” and emphasized its status as a CFTC-regulated exchange. Polymarket said it “maintains a comprehensive market integrity framework.”

In other news, hours after Comer’s announcement, Kalshi unveiled Americans for Fair Markets, a new “well-capitalized” advocacy group tapped to lobby Capitol Hill, led by former Trump White House communications aide and pro-Trump Super PAC leader Taylor Budowich. Polymarket has not announced an equivalent lobbying push.