Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of (NASDAQ:AMZN) were stunning the market today, closing up 9% higher after topping sales estimates in its third-quarter report, and hitting an all-time high.

So what: The all-and-sundry online retailer continued to grow at a blistering pace, as revenue increased 24% in the quarter, or 26% in constant currency, to $17.09 billion. Analysts had expected sales of $16.7 billion. Amazon reported a quarterly loss for the quarter at $0.09 a share, but the market long ago stopped worrying about the online behemoth's bottom line, content to see its market power and reach grow instead. CEO Jeff Bezos touted the company's new releases of the Kindle Paperwhite and Fire, as well as its new video tech-support service, Mayday, while the company's guidance was so broad and conservative as to be essentially useless.  

Now what: Amazon's sales may be growing faster than the speed of light, but every time the stock moves up like this, its valuation seems harder to justify. Still, the market seems unconcerned with that anomaly. Amazon is a unique company with a monopoly-like position in online retail, and commanding positions in other areas such as e-book publishing, digital media, and cloud computing services. On top, it has the wherewithal to bring everything together with its Prime service offer, giving it an even stronger competitive advantage. Who knows what the future holds for Amazon, but every jump in sales translates into increased switching costs, and greater networking effects, as the company moves closer to its goal of same-day delivery, which would be a game changer. Its valuation may make observers scratch their heads, but I wouldn't bet against it.

Fool contributor Jeremy Bowman has no position in any stocks mentioned. The Motley Fool recommends The Motley Fool owns shares of 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.