Walmart originally started out by putting stores in those areas that had recently turned from cornfields into sprawling developments--areas that were so new that other retailers didn't even know they existed---they were incredibly successful because most of the areas had no retail infrastructure at all--they took profits and invested them in new stores, and got to be very good at building new stores and opening them fast--the thing is that now they have expanded into everyplace that fit their original marketing model, and(because expansion is necessary in their business model) are forced to move into areas that it isn't quite so easy to get that "instant market dominance"--

The other thing is that other retailers have followed them into their original markets, and are taking big chunks of their market share--Their clothing business is getting eaten into by Target, TJ Maxx, Marshalls, Ross, and number of others who offer better quality, more stylish clothing, with brand names, at the same prices that WM is asking--Circuit City and Best Buys are cutting their electronics and appliance business to ribbons because they have so much more stuff(if you want to see a mecca to consumerism, Little Hawk, you gotta check out Circuit City)--

Bottom line is that Walmart, though it is the biggest retailer in the world, doesn't have much to attract new customers, and they are losing some of of their old ones--that's why their going into the mega-grocery business--the thing is that the grocery business works a whole different way than the discount retail business, and they will be fighting for a share of already established markets--When you're as big as WalMart, and you start to lose money, it is going to be on an enormous scale--