Irvine-based Western Digital Corp. said Thursday evening that it has completed its acquisition of Hitachi Global Storage Technologies, in a deal worth $3.9 billion in cash plus $0.9 billion in WD common stock. The acquisition of Hitachi Global Storage Technologies creates a firm with annual revenues of $15 bilion. As part of the acquisition deal, WD said that Hitachi Ltd. now owns approximately 10 percent of WDC's shares outstanding, and will add two individuals to its board of directors. The close of the deal has been more than a year in coming; the deal had originally been announced in March of 2011.