$10 billion auto parts firm Genuine Parts ( GPC) is the firm behind the NAPA brand of automotive parts, distributing more than 400,000 parts to 5,000 stores spread across North America -- 1,000 of which are company-owned. NAPA also owns industrial and electronics businesses, wholesaling mission-critical parts for industrial equipment. The business has a big target on its back right now; short sellers have bid the firm's short interest ratio to 8.6. GPC's biggest business is NAPA auto parts at around half of sales. That exposure is especially attractive right now given the aging vehicle fleet in North America: at present, the average car on the road is older than ever before at 11 years. As consumers try to wring more time out of their existing vehicles, every firm involved in the process should benefit. An abundance of consumable products on its shelves also means that customers keep coming back. Much like Sysco, GPC's real claim to fame is its distribution network. Because the firm has built deep expertise at getting products to stores and customers quickly and cheaply, it has immense advantages over rivals who don't have the same network effect. Financially, GPC is in strong shape, with a cash balance that offsets around a third of the firm's total debt. That, and impressive cash generation each quarter, should keep the firm's hefty 3.2% dividend payout flowing for the foreseeable future. Oct. 18 earnings could be a big catalyst for upside that triggers a short squeeze.