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 clothing retailer Aeropostale (NYSE: ARO) were looking very unstylish to investors today as they fell as much as 20% after the company's first-quarter earnings report.

So what: Earnings per share fell 58% from last year to $0.40, while revenue inched up 1% to $469 million. Sales were slightly softer than expected, but Wall Street was well-prepared for the drop in earnings and had predicted $0.40 per share. However, they weren't as prepared for the company's second-quarter guidance. Management sees earnings per share in a range of $0.11 to $0.16 for the upcoming quarter, which is easily short of the $0.27 that Wall Street was hoping for. Inventory and rising costs appear to have a big hand in the lackluster expectations.

Now what: Aeropostale CEO Thomas Johnson said the company is "disappointed with our current performance," and I'm sure investors feel the same way -- though possibly with less-publishable words. On the upside, the company does still sport an impressive debt-free balance sheet with roughly $140 million in cash, and it's aggressively buying back its own shares. But with margins plunging from a year ago and the operating environment not improving quickly, the company needs to get its act together or investors will continue to find other places for their money.

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