Strong sales for the iPod, the successful launch of the new generation iPhone and the halo effect for the company's established line of computers have driven Apple's share price 44% higher over the past year.
In contrast, Google's shares have declined from their peak late last year, when they rose above $700, as investors have started to worry about the company's ability to sustain its stellar growth rate and the slowdown in America has dampened online advertising.
As a result Apple overtook Google's market valuation of $157.2bn (£84.8bn) on Wednesday, closing the day on the Nasdaq stockmarket worth £158.8bn.
However, Apple chief executive Steve Jobs' moment ahead of Google founders Larry Page and Sergey Brin was brief. Google regained its lead last night after its shares rose 1% and Apple's remained flat.
Yahoo!, which has suffered a long downturn in fortunes after being outmanouevred by Google in search, is currently worth $28.1bn.
The company yesterday appointed former Viacom chief executive Frank Bioidi and former Nextel Partners chief executive John Chapple to its board as part of its settlement with activist investor Carl Icahn.
Icahn in return has climbed down from his campaign to force Yahoo! into agreeing to be acquired by Microsoft, currently worth $254.8bn.