Amazon.com (NASDAQ:AMZN) is losing its sales-tax advantage, and the stocks of competitors are rallying so far in 2013. Is the e-tailer's selling threat waning? Fool contributor Demitrios Kalogeropoulos doesn't think so. He discusses two big reasons Amazon is still a force to be watched in the retail space.

Fool contributor Demitrios Kalogeropoulos and Erin Miller have no position in any stocks mentioned. The Motley Fool recommends Amazon.com and eBay and owns shares of Amazon.com, eBay, and RadioShack. Try any of our Foolish newsletter services free for 30 days. We Fools don't 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.