Here is the email that Jobs sent to Apple employees this afternoon:
Team,
I am sure all of you saw my letter last week sharing something very personal with the Apple community. Unfortunately, the curiosity over my personal health continues to be a distraction not only for me and my family, but everyone else at Apple as well. In addition, during the past week I have learned that my health-related issues are more complex than I originally thought.
In order to take myself out of the limelight and focus on my health, and to allow everyone at Apple to focus on delivering extraordinary products, I have decided to take a medical leave of absence until the end of June.
I have asked Tim Cook to be responsible for Apple's day to day operations, and I know he and the rest of the executive management team will do a great job. As CEO, I plan to remain involved in major strategic decisions while I am out. Our board of directors fully supports this plan.
I look forward to seeing all of you this summer.
Jobs' health has been in the spotlight for months due to his frail appearance, with speculation running even more rampant after the Apple CEO decided to not give the keynote at this year's MacWorld. At the time, it was disclosed that Jobs was suffering from a hormone disorder.
Trading of Apple shares has been halted after-hours on the Nasdaq, and will resume at 5pm ET. As for how they might perform, back in October, an erroneous report about a Jobs heart attack sent shares spiraling downward by more than 10 percent until the news was quickly refuted by Apple.