On May 9, 2017, Senator Elizabeth Warren (D-MA), along with seven additional Democratic Senators, sent a letter to the Securities and Exchange Commission (SEC), the U.S. Environmental Protection Agency (EPA), and the Commodities Futures Trading Commission (CFTC) requesting an investigation into the activities of Carl Icahn for potential insider trading, market manipulation, and other securities and commodities law violations in the renewable fuel credit market.  The letter states that the actions of and the massive profit earned by Icahn raise questions related to conflict-of-interest rules that apply to government officials, and questions regarding insider trading and market manipulation of renewable fuel credits, known as Renewable Identification Numbers (RIN) -- which SEC, EPA, and CFTC have jurisdiction over.  EPA oversees the issuance and trading of RINs.  CFTC works with EPA to ensure integrity in the RIN market since it has broad authority to prevent insider trading and other market manipulation in commodities markets and futures markets.  SEC has jurisdiction to investigate whether Icahn’s actions as a senior adviser to President Trump affected CVR Energy's stock value or the accuracy of the company's annual and quarterly financial reporting and disclosure.

The Senators maintained that RIN insider trading and market manipulation hurts all parties, including biofuel producers and refineries, and requested an investigation by the three agencies based on the publically available information detailed in the letter.  The Senators also requested information on whether EPA Administrator Scott Pruitt and SEC Chairman Jay Clayton would recuse themselves from the investigation.