Federal-Mogul Holdings Corp. agreed to be acquired by billionaire investor Carl Icahn’s investment company. The maker of Champion spark plugs will be closely held by Icahn Enterprises, which already held almost 82 percent of the company, as Icahn seeks to unify auto-parts making and retailing companies.

The price of $9.25 a share is 86 percent more than Southfield, Michigan-based Federal-Mogul’s closing share price of $4.98 on Feb. 26, the day before Icahn Enterprises’ original proposal of $7. The bid was increased to $8 in June. Trading was halted when the deal was announced.

Icahn is seeking to bring together three companies that deal in auto parts. His company also owns service and retail chains Pep Boys and Auto Plus, which could guarantee sales of Federal-Mogul products such as Anco wiper blades and Wagner brake parts.

Earlier on Tuesday, Volkswagen AG announced that it was buying a stake in Navistar International Corp., the U.S. heavy-truck maker that lists Icahn as its largest shareholder. The investment puts Europe’s largest automaker on equal footing with Icahn and Mark Rachesky, another activist, at the Lisle, Illinois-based company.