Shares of oil refiner CVR Energy have nearly doubled since Donald Trump's election, providing a windfall to investor Carl Icahn, who will advise the president on regulations — including a rule change that would benefit the company.
The stock rose 98.5 percent between Trump's election and its closing high earlier this month, as the Financial Times pointed out on Friday. Just before Friday's close, it was up nearly 81 percent, following a 6 percent slide on the day.
The stock is up about 8 percent since the presidential transition team announced on Dec. 21 that Icahn would serve as "a special advisor" to Trump.
The broader S&P 500 energy sector is up about 7 percent since the election, supported by Trump's fossil fuel-friendly "America First" energy policy.
Icahn controls 82 percent of CVR Energy and has long railed against a federal rule that requires refiners that cannot blend ethanol into gasoline to buy credits instead. He has continued to bring up the issue in media appearances since being recruited by Trump.
The rule hurts so-called merchant refiners like CVR Energy because they do not blend fuels, which means they have to buy credits from larger refiners with blending and retail operations, such as Valero Energy and Marathon Petroleum.
Shares of Marathon are up more than 16 percent since the election, while Valero has gained about 15 percent.
To be sure, Valero warned last July that its cost of complying with the Renewable Fuel Standard, largely related to the credits, could double in 2016.
Former White House ethics advisors told CNBC last month that Icahn's role presented a clear conflict because it puts him in a position to influence the president to repeal the regulations and thereby help CVR. That would potentially boost CVR's stock price and enrich Icahn.