For the past 13 years, Steve Ballmer has ruled Microsoft as its CEO. He oversaw the rollout of four Windows operating systems including the most recent Windows 8. Most of us thought he’d be around for the release of Windows 9, or whatever else is next, but it looks like the CEO that wouldn’t quit is finally doing just that.

Ballmer announced today that he will be retiring within the next 12 months. He doesn’t give an exact date as his retirement is entirely dependent upon the company finding his successor. Oh, and before you ask, there’s no word yet either on who might be replacing him.

So, why is Ballmer choosing now to retire? After all, he just announced a massive restructuring plan that will see Microsoft transition into a devices and services company. Surely he would want to be around for that, right? Well, according to an internal email to all Microsoft employees, Ballmer says that was the original plan:

There is never a perfect time for this type of transition, but now is the right time. My original thoughts on timing would have had my retirement happen in the middle of our transformation to a devices and services company focused on empowering customers in the activities they value most. We need a CEO who will be here longer term for this new direction.

Ballmer’s logic is surprisingly sound. The transition to a devices and services company will take a long time, and he isn’t getting any younger. Microsoft is going to need a younger executive team that can stick it out for the long haul.

In regards to that executive team, Ballmer is optimistic that the current team in place will help move Microsoft into its next phase of growth:

This is a time of important transformation for Microsoft. Our new Senior Leadership team is amazing. The strategy we have generated is first class. Our new organization, which is centered on functions and engineering areas, is right for the opportunities and challenges ahead.

Microsoft is an amazing place. I love this company. I love the way we helped invent and popularize computing and the PC. I love the bigness and boldness of our bets. I love our people and their talent and our willingness to accept and embrace their range of capabilities, including their quirks. I love the way we embrace and work with other companies to change the world and succeed together. I love the breadth and diversity of our customers, from consumer to enterprise, across industries, countries, and people of all backgrounds and age groups.

I am proud of what we have achieved. We have grown from $7.5 million to nearly $78 billion since I joined Microsoft, and we have grown from employing just over 30 people to almost 100,000. I feel good about playing a role in that success and having committed 100 percent emotionally all the way. We have more than 1 billion users and earn a great profit for our shareholders. We have delivered more profit and cash return to shareholders than virtually any other company in history.

As stated above, Microsoft is just starting to look for Ballmer’s replacement. The company’s Board of Directors has put together a committee comprised of Bill Gates, John Thompson and others who will consider potential candidates from inside and outside of the company.

“As a member of the succession planning committee, I’ll work closely with the other members of the board to identify a great new CEO,” said Gates. “We’re fortunate to have Steve in his role until the new CEO assumes these duties.”

Until Microsoft announces a successor, let the speculation begin. I would bet on Steven Sinofsky if he was still with the company, but that’s unlikely to happen now.

[Image: Wikimedia Commons]