Western Digital is now the world's largest hard drive manufacturer in the world. This week, the company announced that its previously announced acquisition of Hitachi Global Storage Technologies has now become official. The deal was made with $3.9 billion in cash and 25 million shares of WDC common stock valued at approximately $0.9 billion, making the final acquisition $4.8 billion.

This move means that WD Technologies and HGST will now operate as subsidiaries of Western Digital. It also means that Western Digital now has about $15 billion in yearly revenue. That surpasses its biggest rival Seagate to make Western Digital the world's biggest hard drive maker.

This new merger also means that there are now only three major manufacturers of traditional PC hard drives in the world: Western Digital, Seagate and Toshiba. Seagate previously acquired Samsung's hard drive division in December for $1.4 billion.

Hard drive companies have been suffering for the past several months thanks to the massive flooding in Thailand. The flood caused a number of hard drive factories to shut down operations. It also caused prices of PC hard drives to increase. The effects of the flooding will still likely affect hard drive supplies for several more months.