You must have more time and money on your hands than you know what to do with. When I go shopping, I prefer to go to one place and get everything I need with one trip. Granted, I have to put a little bit of trust in Wal-Mart considering the fact that I don't check prices at other stores. I simply expect they are competitive or cheaper in most cases.
Just as a continuation, exactly what type of "stock" are you looking to buy? Most of my Wal-Mart shopping consists of groceries and hygiene related items.