Donald Trump Jr. leaves Kalshi after investment in Polymarket — Ars Technica
In the United States, Donald Trump Jr. has ceased serving as a strategic adviser to prediction market platform Kalshi following a significant investment by his venture firm, 1789 Capital, in competitor Polymarket. As Ars Technica reports, the parties agreed to end their cooperation because of 1789 Capital's investment in the competing company.
Kalshi said it was grateful to Trump Jr. for helping promote the platform among clients. A company spokesperson said discussions of his role began back in August, when 1789 Capital's investment in Polymarket became known. Kalshi acknowledged that simultaneously advising two competitors in a developing sector complicated the situation for both sides.
Interests in two platforms
Trump Jr. is a partner at 1789 Capital and an adviser to Polymarket. His firm's $300 million investment in Polymarket was reported in August 2026; it supplemented a smaller investment made in August 2025.
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At the same time, he may retain a financial interest in Kalshi. According to the Financial Times, after being appointed strategic adviser in early 2025, Trump Jr. received a stake in the company worth approximately $300,000. Kalshi announced his appointment on January 13, 2025 — more than two months after the U.S. presidential election and one week before Donald Trump's second inauguration.
Regulatory disputes
Kalshi CEO Tarek Mansour previously said that Trump Jr.'s role concerned marketing and explaining how prediction markets work, rather than regulatory matters. The U.S. presidential administration supported the development of such markets through the approach of the U.S. Commodity Futures Trading Commission, which also filed lawsuits against states seeking to regulate the platforms' activities more strictly.
Attorneys general in a number of states accuse Kalshi of organizing illegal gambling. The company insists that its wagers are event contracts subject exclusively to federal regulation. Senators Elizabeth Warren and Jeff Merkley, in a letter to the White House counsel, expressed concern over the Trump family's financial interests in Kalshi and Polymarket.
