20. Western Digital
CEO: Stephen Milligan
Hard drive and solid-state disk manufacturer Western Digital expanded the scope of its business through a series of strategic acquisitions in 2012. Those included sTec, an early leader in the SSD market, and Arkeia Software, a developer of data protection software.
The acquisitions continued in the third quarter with a deal to buy flash storage developer Virident for $685 million, giving the company a strong flash storage portfolio.