Three years ago Amazon was a struggling third in the BrandZ Most Valuable Global Retail Brands study.

This year it has overtaken global bricks and mortar powerhouse Walmart for top spot in a telling testimony to the growth of online retailing.

When the first BrandZ study was conducted in 2009 by Millward Brown Optimor, in association with global advertising and marketing company WPP, retail brands were struggling to navigate through the recession, unsure when the consumer appetite for spending would return and what shape it would take.

Amazon ranked third with a valuation of US$21.3 billion, about half of Walmart’s, which topped the chart.

This year, Amazon’s brand value has been assessed at US$37.6 billion, reflecting what WPP’s David Roth describes as “extraordinary vision and performance”.

“But it also crystallises the transformative influence of digital on shopper habits and portends much more to come,” said Roth.

Millward Brown Optimor provided the valuations based on BrandZ, the world’s largest and most comprehensive brand equity tool. Since its creation 13 years ago, over 2 million consumers and B2B customers across more than 30 countries have shared their opinions about thousands of brands.

The study was released at the World Retail Congress in Berlin.

A PDF of the Top 20 retail brands report can be downloaded here.