Why Wal-Mart? For one thing, Wal-Mart is huge. It is America's, and the world's, biggest company (in terms of revenues), and also America's, and the world's, largest private sector employer. Using the figure listed here on Walmart's 2007 revenues, and the figures for the U.S. GDP in 2007 listed here and here (which all give slightly different estimates for the GDP), I calculate that Wal-Mart's revenues are equal to approximately 2.7% of the gross domestic product of the United States.Yeah, I suppose large successful employers deserve to be attacked for hiring so many people. The only reason I bring this post up is because it makes a very common mistake by comparing revenue to GDP. You most often see this with comments like "Wal-Mart is larger than the economy of (insert 3rd world country here)."
Arguments based on comparing GDP to revenue is about as useful as gauging the nutritional value of a fruit based on its relative size. You cannot say the pineapple is more nutritious than the potato simply because it is bigger, you have to compare potatoes-to-potatoes and pineapples-to-pineapples if you want to talk about size and nutritional content.
The principle reason is that GDP is a measure of value-added, whereas revenue is not. The sale-price of a good includes not just the input of Wal-Mart, but the input of all those in the supply-chain, for which Wal-Mart is almost certainly a very small portion of (See I, Pencil by Leonard Read). It would be more (but not entirely) accurate to compare firm profits to GDP, but this is not done by Wal-Mart detractors because it would reduce their estimates to the point where it would not even be considered a rounding error.
Hat Tip: Marginal Revolution