In the 13 years that Steve Ballmer has led Microsoft, literature has climbed out of books, songs have freed themselves from CDs and computers have leapt off their desktops into our hands. An exhilarating new world of technology has emerged with little help from a company that once dominated the industry.

Wall Street greeted word of Ballmer's looming retirement with glee, bidding up the company's stock by more than 7 percent after Friday's announcement. But analysts say the firm's fortunes still will face the problem that undermined Ballmer: Microsoft's profits are tied to the popularity of personal computers, a technology declining steadily in our increasingly mobile world.

Ballmer, 57, recently had sought to pivot away from the PC, shifting strategy, instituting a corporate shake-up and releasing new products aimed at the tech-savvy consumers that long had shunned many Microsoft offerings. Yet, as often was the case under his tenure, Ballmer moved too little, too late, analysts said.