Apple CEO Steve Jobs has said that he is to take medical leave from the company, and will return as soon as he can.
The announcement, made on Monday by email to company employees, said that Tim Cook, the chief operating officer, would handle the day-to-day running of Apple, but that Jobs would remain in overall control.
"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," Jobs said in the email.
There is no share trading in the US today as it is Martin Luther King day, a public holiday. However, Apple's first quarter results are due on 18 January. In European trading, Apple's stock had fallen 7.42 percent on the Frankfurt exchange by 1500 GMT on the day of the announcement.
Steve Jobs was absent from the company for six months between 2008 and 2009, when he received a liver transplant. He was diagnosed with pancreatic cancer in 2004, having an operation in the same year to remove a tumour.