Key Takeaways
A Republican senator is calling for Donald Trump Jr. to be subpoenaed over his business dealings—including his ties to Kalshi and Polymarket, two prediction-market companies with major regulatory interests in Washington.
Utah Sen. John Curtis asked the Senate Judiciary Committee to open an investigation into whether presidential family relationships have been used to secure “private financial benefit, preferential treatment, or access” from domestic or foreign interests.
His Sept. 21 letter calls for testimony from both Trump Jr. and Hunter Biden.
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Curtis wrote that Trump Jr. has “significant financial and advisory ties” to prediction-market companies whose futures can be affected by CFTC decisions.
Kalshi named Trump Jr. as a strategic adviser in January 2025, stating he would advise on areas including growth, market strategy, and partnerships.
He later joined Polymarket’s advisory board after 1789 Capital, the investment firm where he is a partner, invested in the platform.
That leaves the president’s eldest son with formal links to the two biggest names competing for the US prediction market.
It comes as Kalshi and Polymarket face state-level challenges over sports-related contracts, while arguing their products fall under federal commodities regulation rather than state gambling rules.
Curtis argued that Congress should examine whether family connections can create real or perceived expectations of favorable government treatment.
Trump Jr.’s spokesman, Andrew Surabian, has previously said Trump Jr. does not trade on prediction markets or speak to the federal government on behalf of either company.
The Trump family’s broader business orbit has also moved closer to prediction markets.
Trump Media announced plans for a Truth Social product, Truth Predict, in October 2025, in partnership with Crypto.com.
The original proposal envisaged contracts tied to elections, sports, economic data, and other events.
However, Trump Media later scaled back the launch plans after pushback.
It said its initial involvement would focus on marketing and promotional work with Crypto.com while Truth Predict remained under development.
While it is separate from Trump Jr.’s work with Kalshi and Polymarket, the arrangement puts another Trump-connected business in the same politically contentious sector.
Curtis’s request has secured support from the Senate Judiciary Committee’s ranking Democrat, Dick Durbin.
Durbin said on Sept. 23 that the committee should hear from Trump Jr., arguing that Hunter Biden has already given sworn congressional testimony regarding alleged corrupt activity.
Republicans spent years scrutinizing Hunter Biden’s foreign business relationships.
Curtis now argues that oversight should not disappear when the questions involve a Republican president’s son.
The decision over Trump Jr. lies with Senate Judiciary Committee Chairman Chuck Grassley.
Grassley has said he will review the request and collect more information before deciding whether the committee should act.
The committee’s public schedule does not currently list a hearing involving Trump Jr.