by Itunuoluwa Adebo

A group of Democratic lawmakers, led by Senator Elizabeth Warren, urged U.S. regulators to investigate whether billionaire investor Carl Icahn used his role as an adviser to the White House to gain unfair trading advantages in the market for renewable fuel credits.

Warren and other senators asked agencies including the Securities and Exchange Commission and the Environmental Protection Agency to review if Icahn engaged in insider trading or manipulated markets, according to a letter released Tuesday. The letter refers to Icahn as the majority owner of CVR Energy Inc, and may have influenced policy decisions that drove down the cost of fuel credits so that he could buy them back at a cheaper price,

“We have no way of knowing at this time whether Mr. Icahn made any of his renewable fuel credit trades or decisions about trades based on material, non-public information or otherwise manipulated the market,” the senators wrote. “But the publicly available evidence is troubling.”

Warren has previously asked regulators to look into Icahn’s role as a special adviser to President Donald Trump, arguing that the arrangement is prone to conflicts considering Icahn’s extensive investment portfolio. Icahn, who was named an unpaid special adviser on regulations in December, has argued that Trump is under no obligation to take his advice.