Google is the world's most powerful brand with a value of $66.4bn, according to an annual ranking by a market research firm. 

The Brandz Top 100 study (PDF) by Millward Brown said that the search engine's brand value has increased by 77 per cent since last year. 

Microsoft fell from last year's top ranking to third place with a value of $54.9bn. General Electric came in second at $61.9bn. 

Other high ranking technology vendors included IBM (10th at $33.6bn), Nokia (12th at $31.7bn), HP (15th at $25bn) and Apple (16th at $24.7bn). 

"Success stories from this year's Brandz Top 100 demonstrate that winning brands leverage major market trends effectively to create business value," said Joanna Seddon, chief executive at Millward Brown.

"Strong brands are capable of extending into areas of opportunity to access new revenue streams and to help businesses respond to market changes."

The ranking attempts to put a dollar value on a brand based on current and expected future earnings.

The figure is generated from hard economic data as well as softer variables such as intangible consumer loyalty and perceived growth potential.

Strong brands in the field of technology have to be able to stretch to include new product categories and converge with existing categories.

The study touted Apple's iPhone, Sony Ericsson's Walkman branded mobile phone and Nokia's all-in-one mobile computers as examples illustrating the convergence trend.

Silicon Valley Sleuth: Google scores top brand position