Mr. Icahn announced his resignation a few hours before The New Yorker published an online article about the conflicts created by his advisory role. The writer, Patrick Radden Keefe, later said on Twitter that the White House told him Mr. Icahn had been fired as an adviser on Monday.
The advisory role with Mr. Trump had raised concern because Mr. Icahn had taken a strong view on regulatory issues that could have benefited some of his investments.
One of his investment firms, Icahn Enterprises, owns a big stake in an oil refinery business called CVR Energy. And Mr. Icahn has been vocal about environmental regulations. In a front-page article in March, The New York Times detailed how Mr. Icahn had pressed for a change in a requirement that refiners be held responsible for ensuring that corn-based ethanol is mixed into gasoline.
“Following his apparent failure to win a regulatory change on ethanol rules that would benefit his personal empire, Carl Icahn is taking his ball and going home,” Robert Weissman, the president of the nonprofit advocacy group Public Citizen, said Friday.
Earlier this year, several Democratic senators demanded that Mr. Icahn step away from his advisory role because of the potential conflict of interest.
In recent months, Mr. Icahn told at least one close associate that he was frustrated with the scrutiny that the position had cast upon him and his business.
