A Christmas rally in Apple's share price made it the world's third most valuable new technology company, behind Microsoft and Google, sealing one of the most dramatic corporate turnrounds ever achieved.

The stock price surge has taken the maker of iPods and Macs past industry stalwarts such as IBM and Intel and was capped this week as Apple topped even Cisco, the networking equipment maker. With a market capitalisation of $174bn, up more than $100bn from a year ago, Apple is one of Wall Street's stand-out successes.