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Kalshi said he was cutting ties with Donald Trump Jr. a week after Democrats won the midterm elections, pledging to investigate ties between the U.S. president’s family and American businesses.
The prediction market platform said Thursday that it had “mutually agreed to end Don’s advisory role” at the company, which began early last year, shortly after the president’s eldest son endorsed Kalshi for correctly announcing the outcome of the 2024 election.
Kalshi gave Trump Jr around $300,000 of equity in the company as part of the deal, the FT previously reported. The platform’s valuation has since increased 20-fold to reach $40 billion.
Kalshi on Thursday blamed the rift with Trump Jr. on his company’s “significant investment in a competitor last summer.”
Trump Jr joined the advisory board of rival prediction market platform Polymarket in August 2025. An investment firm where he works as an associate, 1789 Capital, publicly announced its first investment in Polymarket at the same time.
Polymarket has been in talks since late summer about a $1 billion fundraising at a $21 billion valuation, with 1789 Capital set to increase its stake as lead investor.
A person familiar with the matter said Kalshi initially gave Trump Jr permission to advise his competitor, but both sides recently concluded that deal no longer made sense.
A spokesperson for Trump Jr said the rift was mutual.
Prediction markets including Kalshi and Polymarket allow traders to bet on binary outcomes on everything from football matches to election results, and have benefited from a light regulatory environment under the Trump administration. Both platforms attract billions of dollars in trading volume every month.
But Democrats’ midterm victory last week threatens to derail the companies’ rapid growth and comes as states increasingly challenge the platforms’ right to offer sports betting within their borders.
Republican Sen. John Curtis and Democratic Sen. Elizabeth Warren — who is expected to head the Senate Banking Committee in January, with the power to issue subpoenas — wrote Kalshi and Polymarket last month asking for information on their efforts to prevent insider trading and market manipulation.
Jamie Raskin, the Maryland Democrat expected to chair the House Judiciary Committee in the next Congress, told the FT this week that “we have seen the most breathtaking and outrageous conflicts of interest permeate the Trump administration, starting at the top.”
Polymarket tapped Marc La Vorgna, a former spokesperson for billionaire Michael Bloomberg and founder of the public affairs group MLV Strategies, in September in anticipation of a Democratic victory in the midterms.
Trump Jr did not invest his own money in Kalshi when he joined as an adviser, a person familiar with the matter told the FT in June, and his $300,000 stake was heavily diluted as the company issued new shares.
Kalshi declined to comment on the status of Trump Jr.’s attendance on Thursday.
Additional reporting by Alex Rogers in Washington
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