It’s not exactly a gold watch. Steve Ballmer, the veteran CEO of tech titan Microsoft, announced today that he’d be leaving the company within a year. On cue, shares surged 8 percent, adding about $20 billion in market capitalization to the Seattle software giant. Ballmer, an early Microsoft employee, has run the company for 13 years—an astonishingly long tenure for the CEO of a tech company. But while Microsoft still makes plenty of money, it has had great difficulty adapting to the post-PC world. Since Bill Gates stepped down, the company has been unable to replicate its operating system and software success in the world of music, content, tablets, gaming, and software. As a result, the company’s stock today trades about where it did in 1999.