When Steve Jobs sneezes, Apple catches a cold

This week Apple announced its most successful financial quarter in the company's history. Sales surged, forecasts were surpassed. So why has the share price fallen through the floor, shedding more than 10 per cent in after-hours trading?

Investors are worried - worried about the health of the US economy and its effect on future technology sales; but worried in particular about the health of CEO Steve Jobs, and its effect on Apple.

Rumours about Jobs's fitness have been circulating ever since the announcement of the new iPhone back in June. On stage in San Francisco, he looked gaunt (right). Jobs had suffered from a rare form of pancreatic cancer back in 2004. As ever, bloggers and pundits were quick to cook up a story.

In an attempt to halt the online rumour mill, Apple issued a statement explaining that Jobs was taking antibiotics for "a

common bug"; but the issue of Jobs's health returned this week during Apple's conference call to investors, when chief financial officer Peter Oppenheimer was forced to respond to some uncomfortable questions.

People who have met with Jobs since his June appearance claim he still looks underweight; and he was notable by his absence from the conference call. Investors remain spooked. The problem is that an Apple without Steve Jobs is almost unimaginable.

Jobs co-founded Apple in 1976, and helped run the company until 1985, when he resigned in the wake of a nasty boardroom battle. His departure coincided with the start of a troubled period for Apple in which poor marketing, fierce competition from Microsoft and a confusing product line left the company floundering.

Jobs returned with great fanfare in 1997, and is credited