Apple CEO Steve Jobs said on Monday the company's board of directors had granted him a medical leave of absence to allow him to focus on his health.
Jobs will continue as CEO and be involved in major strategic decisions for the company, but has asked Chief Operating Officer Tim Cook to be responsible for all of Apple’s day-to-day operations, Jobs said in an an e-mail sent to Apple employees.
"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," Jobs wrote.
The news came nearly two years to the date after Jobs first took a six-month break to undergo a liver transplant.
"It wasn't expected. This will come as a surprise to Apple investors and definitely take some shine off the Apple stock," said Alexander Peterc, an equity analyst at Exane.
"This time around you have to question his ability to bounce back," said Hudson Square Research analyst Daniel Ernst.
"[E]ven if Steve Jobs never returns to Apple, I would not expect a visible, tangible impact on how Apple is executing over the next couple of years," Peterc said.
Richard Windsor, global technology specialist at Nomura, agreed that a Jobs absence should not have a fundamental effect, but added: "Perception of the company is another matter."
"Steve Jobs is seen by the market to be a major force in Apple's strategic direction. If his pancreatic cancer has returned, one could be quite worried," he said.
Apple shares ended down 6.8 percent in Frankfurt; US financial markets are closed Monday in observance of the Martin Luther King, Jr. holiday. Nasdaq futures were down 1.4 percent.
Jobs' health has come into question before, creating large fluctuations in Apple shares. Cook has already managed the company on a day-to-day basis in Jobs' absence previously.
Jobs had surgery for pancreatic cancer in 2004 and also underwent a liver transplant in June 2009.
Apple has been closely identified with the charismatic Jobs, who revived the computer maker's fortunes in 1996 after a 12-year absence from the company he co-founded.
Jobs still appeared thin at recent Apple events, something that did not go unnoticed. But the CEO said last summer he was feeling "great," in response to a question from a reporter.
Apple is scheduled to report first-quarter earnings after the bell on Tuesday, and is expected to say that revenues rose 50 percent as sales of its iPad tablet computer build on momentum of the popular iPhone and earlier iPod.