Apple is now the most valuable company of all time, with a market value of approximately $US623 billion.
The company has now surpassed Microsoft's record of $US620.58 billion set in 1999. However, that figure is not adjusted for inflation.
Apple shares hit $US664.74 in midday trading in New York on Monday and closed at $US665.15. That was $17, or 2.6%, higher than Friday's close.
The BBC reports Apple is about to launch the iPhone 5 and possibly a smaller and cheaper iPad. There is also speculation that Apple plans to make a TV set.
The iPhone is the company's biggest product, yielding half or more of its sales.