How big is Wal-Mart?

This big:

Out of every dollar spent in a store in the U.S., seven and a half cents go to Wal-Mart

Nearly ten percent of China's exports to the U.S. go to Wal-Mart

It does more business than Target, Sears, Kmart, J.C. Penney, Safeway, and Kroger combined.

a McKinsey & Co. study concluded that about 12% of the economy's productivity gains in the second half of the 1990s could be traced to Wal-Mart alone.

Wal-Mart has 21,000 suppliers

How does this kind of size impact their business model? Here's one recent take on that.