He was listed last year as 189th on the Forbes list of the world's billionaires, with a net worth of about $5.7 billion. After selling Pixar animation studios to The Walt Disney Company in 2006, he became a Disney board member and the company's largest shareholder. Disney is the parent company of ABCNews.com.
Analysts said Apple has done fine in Jobs' absence, partly because he has been available for big decisions, partly because he has delegated day-to-day decisions for about five years.
Apple Inc., stock, which dropped to $78.20 a share in January after he announced he was going on leave, has since climbed to above $140 a share.