NEW YORK: Prediction platform Kalshi has ended its collaboration with Donald Trump Jr., citing the financial links between the president’s son and rival firm Polymarket.
“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,” a Kalshi spokesperson said, according to US media reports on Thursday.
Donald Trump Jr., the president’s oldest son, joined Kalshi in January 2025 as a “strategic adviser”. His activities in the prediction markets are just one of multiple business efforts by the Trump family since Donald Trump became president in 2025.
In August 2026, Polymarket announced that Trump Jr. had joined the company’s advisory board following a “strategic investment” by 1789 Capital, in which he is a partner.
US media have reported that 1789 Capital invested US$300 million in Polymarket in August 2026, on top of US$200 million invested in the firm earlier.
Kalshi and Polymarket dominate the growing US prediction market, in which customers can place bets on sporting event outcomes, elections and financial markets, among other areas.
In late July, New York state sued Kalshi, accusing it of running an illegal gambling operation.
Attorney General Letitia James said New York’s gambling laws protect children from underage betting and help fight gambling addiction.
Kalshi faces similar legal challenges in multiple US states, where gaming regulators have issued cease-and-desist orders or filed lawsuits accusing the platform of operating an unlicensed gambling business.
The company has argued that its activities do not constitute gambling but are closer to market trading, allowing people to trade on yes-or-no questions.
In April, US prosecutors brought criminal charges against a US soldier who allegedly made more than US$400,000 on Polymarket by placing bets on the US operation to capture former Venezuelan president Nicolas Maduro using classified information.