Sinofksy handed in his resignation to Microsoft on Monday, after the launch of Windows 8. In an opaque resignation letter, Sinofsky said he was leaving to "seek new opportunities" to build on his experience at the company. Sinofsky will be succeeded by Julie Larson-Green on the engineering side of Windows, and Tami Reller, formerly the division CFO, on the business side.
The exec's departure comes less than a month after Scott Forstall, a similarly influential member of Apple's team left that company. That exit, which was coupled with another from Head of Retail John Browett, prompted a similar depression of Apple's stock price the following day.
After the initial drop this morning, Microsoft's stock price climbed back somewhat and was down about 3% on the day as of publication.
BONUS: Sinofsky's Surface Launch