Activist investor Carl Icahn raised his bid to acquire the remaining stake in auto parts supplier Federal-Mogul Holdings Corp. Icahn, already the company's largest shareholder, said in a letter to the board of directors that he would increase his offer to $8 per share, up from the $7 per share offer he made in February. Icahn Enterprises, which owns 82 percent of the company, would pay upward of $243 million for the remaining 18 percent. After the original offer, Federal-Mogul's board of directors said it would appoint a committee of independent directors to review the offer. The bid to buy the minority stake comes after Federal-Mogul scrapped its plan in January to split the company into two separate public entities. Company officers pointed to market conditions as the culprit behind its decision not to split its aftermarket parts division from its powertrain division. In December, Icahn won a $1.03 billion bidding war for auto parts retail chain Pep Boys. Experts believe Icahn plans to use the parts retailer as a mainline for Federal-Mogul parts but fear his vertical integration strategy will hurt the company over the long term. Pep Boys' 800 stores, paired with Icahn's other aftermarket retailer, the 278-location Auto Plus, would make up the fifth-largest retail auto parts chain in the U.S. Even with Pep Boys' stores, Auto Plus would be significantly smaller than rivals Advance Auto Parts Inc., Autozone Inc. and O'Reilly Automotive Inc. It's unclear whether the Icahn taking full control of Federal-Mogul would expedite that process. Federal-Mogul shares opened at $8.15 on Monday, and rose 4 percent to close at $8.48. The company reported net income of $35 million on revenue of $1.9 billion in the first quarter of 2016.