I grabbed the last four annual revenues for Amazon and Walmart from Google Finance. The average growth (in revenue) for Amazon over that period is 31%; for Walm

I grabbed the last four annual revenues for Amazon and Walmart from Google Finance. The average growth (in revenue) for Amazon over that period is 31%; for Walmart, 9%. World GDP growth is about 7% per year (over the last 30, through '08). Assuming those continue then Amazon will sell $1T nominal in 16 years. Unfortunately for the author's claim, Walmart will do it in 12. And also unfortunately, with that rate of growth, Amazon's revenue will exceed world GDP in 41 years.