But Microsoft also fell out of favor because many investors concluded that it was more interested in protecting its Windows franchise than coming up with new ideas and products to enter promising new markets.
By the time Ballmer took Google more seriously and began pouring money into trying to build a better Internet search engine, Microsoft already was hopelessly behind. The company's online division lost billions of dollars without putting a serious dent into Google's dominance of the field.
Google's rise riled the quick-tempered Ballmer, especially when key Microsoft engineers began defecting to the then-smaller company. After one Microsoft employee met with Ballmer in November 2004 to tell him he was leaving to join Google, Ballmer threw a chair across his office, according to a sworn declaration filed in a lawsuit. Ballmer then launched into an obscenity-laced tirade In which vowed to "kill" Google.
By 2012, the iPhone was generating more revenue than Microsoft was as an entire company and giving people less reason to replace their PCs. Again, Ballmer had to scramble in an attempt to adapt and ordered a dramatic makeover of Windows so it could run on mobile devices, as well. The new system, Windows 8, borrowed many of its ideas from the software that ran the iPhone, just as Microsoft had copied some of the concepts for its early versions of Windows from Apple's Macintosh.
Meanwhile, the iPhone's immense popularity helped Apple overtake Microsoft as the world's most valuable company while Ballmer was CEO.
Windows 8 proved to be Ballmer's last stand, said analyst Patrick Moorhead of Moor Insights & Strategy.
When the operating system launched in October, Moorhead predicted that Windows 8 would be Ballmer's "defining moment." His legacy, he added, would be looked at "as what he did or didn't do with Windows 8." If it's a flop, "a lot of people will be looking for Microsoft to make a change at the CEO level," Moorhead told The Associated Press back then.