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 youth-skewed-apparel retailer Urban Outfitters (Nasdaq: URBN) are as popular as last year's fashion today, falling as much as 16.4% on tremendous trading volume.

So what: Last night's fourth-quarter report missed analyst targets on both the top and bottom lines as the company chased sales through aggressive clearance markdowns and still came up short.

Now what: CEO Glen Senk was happy to report record sales and operating profit, but investors still wanted more, and that operating benchmark was set by a very slim margin. Slimming profiles are more flattering on young bodies than financial statements, dude. Rivals such as Abercrombie & Fitch (NYSE: ANF) and Pacific Sunwear of California (Nasdaq: PSUN) hardly moved on the news, indicating a widespread belief that the problems were Urban Outfitters' own and not a sudden, industrywide shift in fashion tastes.

Interested in more info on Urban Outfitters? Add it to your watchlist.

Fool contributor Anders Bylund holds no position in any of the companies discussed here. 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 is investors writing for investors.