By some standards, Walmart is successful. It has grown and made the family and a few others very wealthy. However, at the moment, as an equity, WMT represents a poor investment - dividend is approx. 0.67% of share price (based on $0.36/share at $53.10), earnings per share is 4.54% - not spectacular (and is certainly not reflected in the dividend) (data from Thomson). The share price has remained relatively flat or somewhat decreasing since last 1999. For the general common stock investor, there are much better investments.
But then -
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Then there is the Wal-Mart discrimination lawsuit. I think if you take aside some Walmart employees - away from the job, you'll find that things are not so rosy. Fear of retaliation is a concern.