Senator Curtis Asks for a Subpoena of Donald Trump Jr., Citing His Prediction-Market Ties

A Republican senator who co-sponsored a bill to classify sports event contracts as gambling wants the Senate Judiciary Committee to question Donald Trump Jr. and Hunter Biden about trading on their fathers' office. Trump Jr.'s ties to Kalshi and Polymarket are one line in the case, and the committee's chairman is in no hurry.

• Senator John Curtis of Utah has asked the Senate Judiciary Committee to investigate "the use of presidential family relationships for private financial benefit" and to subpoena Donald Trump Jr. and Hunter Biden to testify
• His letter of 21 September cites Trump Jr.'s "significant financial and advisory ties to prediction-market platforms that depend on favorable federal regulatory decisions being considered by the Commodity Futures Trading Commission"
• The letter does not name the platforms; Trump Jr. became a strategic adviser to Kalshi in January 2025 and joined Polymarket's advisory board in August 2025, when his fund 1789 Capital invested
• Chairman Chuck Grassley said there was "no way I could answer" when a hearing might happen, while Ranking Member Dick Durbin called the request "a gutsy move"
• Curtis co-sponsored the Prediction Markets Are Gambling Act with Democrat Adam Schiff in March, which would bar sports and casino-style event contracts

A Letter About Presidential Families, With a Line on Prediction Markets

Curtis wrote to Grassley and Durbin on 21 September asking the committee to "launch an investigation into the use of presidential family relationships for private financial benefit, preferential treatment, or access by domestic and foreign interests". He urged it to subpoena Donald Trump Jr. and Hunter Biden "to testify regarding their past business dealings, relationships with foreign individuals and entities, gifts, or other benefits they have received". "The country should not have to accept one standard for the family of a Republican president and another for the family of a Democratic president," he wrote.

The main trigger was a wedding party for Trump Jr., which Curtis described as "a lavish wedding afterparty, on a private island, provided by Russian oligarch Umar Kremlev". The letter also lists crypto ventures, foreign real estate and defence investments. On prediction markets, it says Trump Jr.'s pattern of dealings "extends to his significant financial and advisory ties to prediction-market platforms that depend on favorable federal regulatory decisions being considered by the Commodity Futures Trading Commission", citing the administration's support for Kalshi and Polymarket as states moved against them in February.

The letter names neither company. Kalshi announced Trump Jr. as a strategic adviser on 13 January 2025. Polymarket said on 26 August 2025 that he had joined its advisory board alongside a strategic investment from 1789 Capital, where he is a partner. TechCrunch reported in August 2026 that 1789 Capital had put $300 million into Polymarket's latest funding round. His spokesman told CNN in March that Trump Jr. does not trade on prediction markets and has not dealt with the federal government for either company. iGaming Times has not seen a response from Trump Jr., Kalshi or Polymarket to the letter.

A Committee in No Hurry

The request has divided Curtis's own party. Grassley told NBC News: "I think the fact is that it takes time, and if you were going to ask me when you're going to have a hearing, there's no way I could answer that today." A committee statement reported by the Deseret News framed the idea as partisan: "Now they want hearings on the Trump family?" Durbin said Curtis had "made a strong case", and Republican Senator Thom Tillis said: "If I were Donald Trump Jr. I'd be offering this up immediately." Hunter Biden has said he is willing to testify.

The Prediction-Market Line Matters Because of Who Wrote It

Curtis is not a new critic of the sector. He co-sponsored the Prediction Markets Are Gambling Act with Adam Schiff, which would amend the Commodity Exchange Act to bar sports and casino-style contracts, and at a Senate Commerce hearing in May said of the contracts: "It seems to meet every definition of gambling." Putting Trump Jr.'s advisory roles in a formal request to the Judiciary Committee links two arguments that have so far run separately: that sports event contracts are gambling that belongs under state control, and that the federal regulator deciding their fate is doing so while the president's son advises the two best-known platforms. The letter stops short of alleging wrongdoing, and asks for the facts to be established.

The Risk for the Platforms Is Scrutiny, Not a Subpoena

A Judiciary Committee subpoena looks unlikely on Grassley's timetable. But the letter puts on record a conflict-of-interest argument that state regulators, tribal gaming interests and the platforms' litigation opponents can now quote from a Republican senator, not a Democratic one. Kalshi and Polymarket have based their case on federal jurisdiction through the Commodity Futures Trading Commission. The more their regulatory fortunes are tied in public to the Trump family, the harder it becomes for them to present federal oversight as neutral ground, and the easier it becomes for Congress to argue that the question belongs to it rather than to the agency.

The committee may never call Trump Jr. to testify. The prediction-market industry will still have to answer the question Curtis has raised, in court filings and in Congress.