08/24/2011 at 07:00 PM EDT
Apple co-founder Steve Jobs has resigned as CEO, the company announced Wednesday.
His letter to the board and employees did not mention his health problems, but it was alluded to.
"I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple's CEO, I would be the first to let you know," he wrote. "Unfortunately, that day has come." (For the full letter – sent to Apple's board and later released publicly – see Fortune.com
Jobs, who took medical leave in January
, will remain on as chairman and former Chief Operating Officer Tim Cook will take over as CEO.