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.
The stock price gives California-based Apple a market capitalisation of about US$374 billion, trailing by US$41.6 billion the US$416 billion value of Texas-based Exxon.
Apple's iPhone-fuelled rise comes amid a reversal of fortunes for rival makers of smartphones such as Research In Motion and Nokia, which have lost market share and fired workers.
Apple last week said profit more than doubled to US$7.31 billion on revenue of US$28.6 billion, compared with the same period a year earlier.
The company had record sales of iPhones and iPads, products that didn't exist five years ago and now account for more than 70 per cent of revenue.
Apple also has accumulated US$76.2 billion in cash and other holdings.
"I don't see too much slowing them down," Cherukuri said.