Apple CEO Steve Jobs will take a leave of absence from the company for medical reasons, but will remain involved in major strategic decisions, the company said Monday. He will leave day-to-day operations to COO Tim Cook.
Jobs made the announcement in an e-mail message to Apple employees, the company said.
This is the second leave of absence Jobs has taken. He did not say how long he would be away, nor why.
U.S. stock markets were closed for a holiday on Monday, so it is not clear how investors are taking the news.
Jobs underwent surgery to remove a cancerous tumor from his pancreas in 2004, but told Apple employees then that he would not need chemotherapy or radiotherapy.
However, in public appearances after that, he appeared increasingly gaunt. Concerns about his health affected Apple's stock price in December 2008, forcing him to announce in January 2009 that he would take a six-month leave of absence, putting Cook in charge while he was away.
"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," Jobs wrote in 2009.
In Monday's message, he pointedly requested respect for his privacy, and provided no details of the health issues that have prompted the latest absence.
Jobs initially attributed his 2009 problems to "a hormone imbalance that has been 'robbing' me of the proteins my body needs to be healthy." but later said: "My health-related issues are more complex than I originally thought."
Those complications ultimately necessitated a liver transplant, following which he returned to work in June 2009.
Apple provided a copy of Jobs' latest message to employees, which read:
"At my request, the board of directors has granted me a medical leave of absence so I can focus on my health. I will continue as CEO and be involved in major strategic decisions for the company.
"I have asked Tim Cook to be responsible for all of Apple's day to day operations. I have great confidence that Tim and the rest of the executive management team will do a terrific job executing the exciting plans we have in place for 2011.
"I love Apple so much and hope to be back as soon as I can. In the meantime, my family and I would deeply appreciate respect for our privacy.
Apple's announcement leaves key unanswered questions about Jobs' role in the coming months: What ails him and is it serious? How long will he be out? And will this prompt Jobs, who turns 56 next month, to permanently scale back his work at Apple?
Peter Sayer covers open source software, European intellectual property legislation and general technology breaking news for IDG News Service. Send comments and news tips to Peter at firstname.lastname@example.org.