Kalshi ends Donald Trump Jr.’s advisory contract after 1789 Capital’s Polymarket investment

Kalshi has ended its advisory contract with Donald Trump Jr. after his venture capital firm, 1789 Capital, increased its stake in rival Polymarket. A Kalshi spokesperson confirmed the move to Reuters in an exclusive report published on Nov. 12, 2026.

“We have mutually agreed to end Don’s advisory role after his firm’s significant investment in a competitor this past summer. We are grateful for his contributions in helping us market Kalshi to more customers,” the spokesperson said.

The spokesperson added that the decision was mutual and that talks to end the contract started in August, after 1789 led Polymarket’s most recent funding round. Reuters described Kalshi on Nov. 12 as a $40 billion startup. Polymarket and Trump Jr. did not immediately respond to Reuters’ request for comment.

An adviser on both sides

Kalshi named Trump Jr. a strategic advisor on Jan. 13, 2025, in a post by chief executive Tarek Mansour. The post promised his guidance would “help accelerate our growth, refine our market strategies, and open doors to new partnerships and audiences.” Trump Jr. explained his interest in a post on X, quoted in the announcement: “On Election night at Mar-a-Lago, while biased outlets called the race a coin toss, my family and close friends used the prediction market Kalshi to know we won hours ahead of the fake news media.”

Citing the Financial Times, Reuters puts the value of the stake he received at the time at $300,000. Mansour told CNBC that day that the appointment was not a political choice: “We’re not a political company in any way, shape or form.”

Seven months later, on Aug. 26, 2025, Polymarket announced that Trump Jr. had joined its advisory board and that 1789 Capital, where he is a partner, had made a strategic investment. Terms were not disclosed. In his statement in the release, Trump Jr. called Polymarket “the largest prediction market in the world” and added that “the U.S. needs access to this important platform.” Polymarket had recently completed its $112 million acquisition of QCEX, a CFTC-licensed exchange and clearinghouse, as a path back into the US market.

The summer round

This year 1789 went further. In early September 2026, Bloomberg first reported that Polymarket would raise $1 billion, with 1789 investing around $300 million, citing unnamed people familiar with the matter; multiple reports said 1789 was leading the round at a $21 billion valuation. Forbes summarized the deal on Sept. 1, 2026, and noted a Wall Street Journal report that the new money followed an earlier $200 million investment, making 1789 one of Polymarket’s largest investors.

NPR reported the same day that 1789 itself put the investment at $300 million, which would make the firm one of Polymarket’s top equity holders. At that point Trump Jr. held a financial stake in Kalshi and was an adviser to both companies. Our earlier report on Polymarket’s revenue run rate mentioned the same round.

Scrutiny in Washington

Reuters also looks ahead to Congress. Prediction platforms face the prospect of heightened scrutiny from Democrats there, and Senator Elizabeth Warren has vowed to crack down on insider trading on prediction markets.

In a letter dated Nov. 9, Warren and Senator Jeff Merkley pressed the White House counsel over staff bets on prediction markets. The senators pointed to the Trump family’s ties to the industry, including Trump Jr.’s advisory roles at Polymarket and Kalshi.

The end of the contract closes one of those two roles. Reuters’ report does not say whether Trump Jr. keeps his Kalshi stake or whether anything has changed in his role at Polymarket.

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