Apple has surpassed US$400 a share for the first time, a week after reporting record sales and profit, and is gaining ground on the world's most valuable company, Exxon Mobil.
The shares rose US$4.91 to US$403.41 ($461) in Nasdaq Stock Market trading. Apple has climbed 25 per cent this year.
Apple, on the brink of bankruptcy when chief executive Steve Jobs reclaimed the top job more than a decade ago, now has a bigger market value than Microsoft and Intel combined, fuelled by new products such as the iPhone and iPad.
Shares are up from a stock-adjusted US$5.48 on September 16, 1997 - the day Jobs returned after his 1985 ousting.
"It started with the Mac, then iPods, iPhones and now the iPad," said Giri Cherukuri, head trader for Oakbrook Investments, which manages US$2.7 billion, including Apple shares.