Billionaire activist-investor Carl Icahn. (Brendan Mcdermid/Reuters)

Carl Icahn relinquished his role as “special adviser” to President Trump on regulatory reform on Friday afternoon, capping a tumultuous week for the president’s circle of business counselors.

But Icahn did not say he was stepping down because of the uproar over last weekend’s march and violence in Charlottesville. Instead he said he stepped down to avoid turf conflicts with Neomi Rao, the administrator of the Office of Information and Regulatory Affairs, and to avoid conflicts of interest over regulations that affect an oil refining company he owns.

In May, five Democratic members of the Senate asked the Environmental Protection Agency for information about Icahn’s business interests. But Icahn denied any conflict.

“Indeed, out of an abundance of caution, the only issues I ever discussed with you were broad matters of policy affecting the refining industry,” he said in a letter posted online. “I never sought any special benefit for any company with which I have been involved, and have only expressed views that I believed would benefit the refining industry as a whole.”

Yet Icahn had strong views on a regulation that was hurting his company, CVR Energy. Oil Daily, a trade publication, said on Aug. 4 that the Environmental Protection Agency is planning to reject a regulatory change that Icahn had long sought.

Under a 2007 law designed to promote ethanol use, refiners must blend mandated levels of renewable fuels like ethanol into gasoline. Refiners that don’t do the required blending themselves must buy credits, on open markets or from other refiners.

Flucturating prices for those credits were hurting refiners like Icahn’s. His two refineries were expected to pay more than $200 million to fulfill their obligations.

In his letter on Friday, Icahn hinted that he, like the other top corporate executives who resigned from their advisory roles, had had little contact with Trump himself. He wrote, “I sincerely regret that because of your extremely busy schedule, as well as my own, I have not had the opportunity to spend nearly as much time as I’d hoped on regulatory issues.”