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 department store operator Dillard's (NYSE: DDS) plummeted 17% on Friday after its quarterly results fell short of expectations.

So what: While the company's second-quarter adjusted profit more than doubled to $0.30 per share, it missed the average analyst estimate ($0.39 per share) by more than 20%. When you couple that wide of a whiff with the stock's impressive 150% return over the past year, it's easy to see why Mr. Market is seriously readjusting his expectations today.

Now what: I wouldn't pounce on this plunge just yet. Dillard's improving same-store sales, cost structure, and profits are certainly a positive, but with the stock still up quite a bit over the past several months, much of the optimism continues to be baked into the price. While the department store business isn't exactly attractive, rivals like Nordstrom (NYSE: JWN) and Macy's (NYSE: M) -- both of which reported market-topping quarters today, but whose stocks aren't nearly as hot -- seem like better bets.

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