Apple's Jobs Takes Medical Leave but Remains CEO

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.