Wal-Mart (NYSE:WMT) was once the dominant company in retail, but those days are long over. Same-store sales are falling in the U.S., and international expansion has been a disaster. What's worse is that competitors are now outperforming the company, showing that other retail strategies are winning over Wal-Mart's low prices.

Before its own data breach issues, Target's same-store sales were up last year, outperforming its larger rival. A focus on design rather than just price is drawing higher-end customers who have cash to spend. 

But Amazon.com is the 800-pound gorilla taking share that's significant now that it has $78 billion in annual sales. Clearly, online retail is taking over, and Wal-Mart can't keep up. 

Motley Fool specialist Travis Hoium covers Wal-Mart's troubles and why investors should be cautious with the stock. 

Travis Hoium manages an account that owns shares of Target. Travis Hoium is short shares of Amazon.com. The Motley Fool recommends and owns shares of Amazon.com. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.