They've often been considered one of the best supply chain operations in the world, and aggressively drive their suppliers to lower prices and increase volume.
One classic anecdote is that leading up to a hurricane, Walmart did some data mining and found that poptarts sold like crazy when hurricane watches were declared. Within hours they had dozens of trucks heading to the Florida coast filled with poptarts and they made a lot of money that way.
Unless you have a fast, flexible logistics system and the analytical smarts to back it up, you can't exploit changing circumstances like that.
One classic anecdote is that leading up to a hurricane, Walmart did some data mining and found that poptarts sold like crazy when hurricane watches were declared. Within hours they had dozens of trucks heading to the Florida coast filled with poptarts and they made a lot of money that way.
Unless you have a fast, flexible logistics system and the analytical smarts to back it up, you can't exploit changing circumstances like that.
Edit. Source of Walmart anecdote is here: http://www.nytimes.com/2004/11/14/business/yourmoney/14wal.h...