A high-profile Microsoft executive who led the development of the company's new Windows 8 operating system has abruptly left the company, the software maker confirmed late Monday.
23-year Redmond veteran Steven Sinofsky, who was head of Microsoft's $18 billion Windows unit, has stepped down from his position.
Microsoft will split his responsibilities between two executives. Windows planning head Julie Larson-Green becomes head of Windows software and hardware engineering, while CFO and chief marketing officer Tami Reller takes on the additional role as head of Windows business.
[ For more on Microsoft's strategy for Windows 8 and beyond, see Microsoft: Windows 8 Ends Tablet Era. ]
Both will report directly to Microsoft CEO Steve Ballmer. Ballmer, in a statement, said he was "grateful for the many years of work that Steven has contributed to the company."
For his part, Sinofksy said he decided that, after more than two decades at Microsoft, and after shepherding the launch of Windows 8, it was time for a change.
"After more than 23 years working on a wide range of Microsoft products, I have decided to leave the company to seek new opportunities that build on these experiences," Sinofsky said in an e-mail to colleagues. "My passion for building products is as strong as ever and I look forward focusing my energy and creativity along similar lines."
Sinofsky also addressed Internet chatter that his departure was an indication that the debut of Windows 8 and related products, which hit stores Oct. 26, was not going as well as expected.
"Some might notice a bit of chatter speculating about this decision or timing. I can assure you that none could be true as this was a personal and private choice that in no way reflects any speculation or theories one might read -- about me, opportunity, the company or its leadership," Sinofsky wrote.
Windows 8 represents one of the biggest gambles in Microsoft's history. Under Sinofsky, the company completely revamped the user interface, replacing familiar items like the Start menu and Task Bar with a new GUI, initially dubbed Metro, that presents users with large on-screen blocks called Live Tiles, from which they can access apps and services. The new UI has generally received positive reviews, but some users have complained about its unfamiliarity.
With Windows 8, Microsoft also boldly entered the computer hardware business, introducing a tablet called Surface.
Over the weekend, Ballmer told a French newspaper that Surface sales were "starting modestly," but didn't provide more details. Some hardware makers, particularly Acer, have criticized Microsoft for launching Surface, which they view as competition.
In a research note, Wells Fargo analyst Jason Maynard said Sinofsky's departure could leave Microsoft in the lurch at a critical time. "While we think Windows 8 and Surface have promise, there is still a ton of work ahead to catch iOS and Android," Maynard wrote. "In our view this disruption is less than ideal and creates uncertainty."
In his e-mail, Sinofsky said he would assist with the Windows team's transition to new leadership "however needed." Microsoft shares were down about 4% at one point during opening trading Tuesday.
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