Pep Boys - Manny Moe & Jack said Monday that Carl Icahn's newly unveiled 12.1% stake in the firm could imperil Bridgestone Corp.'s acquisition of the car-parts and repair company. The company said in a statement that Icahn's stake has "raised concerns" that the billionaire investor and other third parties could be trying to purchase the company's auto-parts segment. "Pep Boys shareholders' ability to realize the value presented by the Bridgestone offer may be frustrated," the company wrote. Pep Boys shares rose 6.6% in premarket trading. Pep Boys said in October that it would be acquired by Japanese tire company Bridgestone for roughly $835 million in cash, about four months after the Philadelphia-based company put itself up for sale. On Friday, Icahn disclosed his stake, saying Pep Boys' auto-parts division is an "excellent synergistic acquisition opportunity" for Auto Plus, one of the companies Icahn Enterprises controls. At 6.6 million shares, Mr. Icahn's Icahn Enterprises would be the second largest shareholder in the company. Mario Gabelli's Gamco Investors Inc. reported a 6.9-million-share stake in Pep Boys in October.