Shares of Pep Boys - Manny, Moe & Jack topped corporate buyout artist Carl Icahn's latest offer of $16.50 a share in New York Stock Exchange trading Monday, driving the ailing Philadelphia auto service chain's value to its highest since 2007, as investors bet on whether rival bidder Bridgetstone Retail Operations LLC will top Icahn's bid by Wednesday's deadline.

Pep Boys has 800 locations in 35 states. The company's retail store sales have been declining, while its repair, tire and fleet service businesses are growing.

Bridgestone wants to combine Pep Boys with its 2,000-repair center Firestone chain. Icahn hopes to merge Pep Boys into his AutoPlus parts chain, which has stores in Pennsylvania, New Jersey and other states.

As the price rises either buyer will face more pressure to cut costs at Pep Boys' 500-worker headquarters on Allegheny Ave., regional warehouses and other operations.