Apple becomes world's largest-ever company

Apples  become the most valuable company of all time, after its shares rose 2.6 percent yesterday to reach $665.15.

That gives the company a market cap of $623 billion, narrowly beating Microsoft's record of $613.3 billion in December 1999 - although this comparison doesn't take account of inflation.

Apple's now worth more than Microsoft and Google combined, and over $200 billion more than the world's second-largest company, Exxon Mobile.

It is, naturally, the iPhone that's behind the figures - indeed, the iPhone alone generates more revenues for the company than Microsoft brings in overall. And it's the expectation of a new iPhonenext month - along with, possibly, a smaller iPad - that's fuelled this growth in the company's share price.

But as Bernstein Research's Toni Sacconaghi tells Reuters, the shortage of components that has hit Apple in the past could strike again.

"A key question for the launch will be Apple's expected rollout schedule," the analyst wrote on Monday," he says. "Apple's intention is to continue to ramp offerings as quickly as possible, but the company's ability to do so remains a key near-term question."

Many analysts also question whether the company can keep up its reputation for innovation following the death of Steve Jobs last year.

The rise in Apple's value over the last few years has been extraordinary. Eight years ago, it was worth just $10 billion, and shares have risen by 60 percent this year alone.

The news will make galling reading for investors in Facebook, who have seen the value of their shares slide since the company went public in May. They're now hovering at around the $20 mark, well down on the $38.23 at launch.