The companies employed 474,168 worldwide, down 3.5% from a year ago. Their combined sales hit about $56 billion last year, a 0.2% change. • The top two employers—Western Digital Corp. and Toshiba America Information Systems Inc., both based in Irvine—accounted for nearly all of the job losses as PC sales last year sunk to the lowest levels since the depths of the Great Recession in 2008. • No. 1, WD, the world's largest disk drive maker, shed 204 positions in Orange County, to about 1,700 local workers, down 10.7% from a year ago. The company last year initiated a restructuring plan that eliminated 180 positions, mostly in the U.S., and primarily in California, that affected engineers, managers and administrative personnel. Its $17 billion takeover of Milpitas-based SanDisk Corp. closed last week, creating the most diversified company in the storage market, with annual sales nearing $20 billion.