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 Hanger Orthopedic (NYSE: HGR) plummeted more than 20% in early trading after issued worse-than-expected fourth-quarter guidance. The stock closed off 15.7%.

So what: Third-quarter earnings came in a penny ahead of expectations at $0.46 on $235.2 million in revenue, about $2.5 million short of estimates.

Now what: For Q4, the prosthetic-device specialist expects to earn $0.49 to $0.52 in profit on $243 million to $247 million in revenue. Analysts, by contrast, had been projecting $0.58 a share on $261.9 million in sales. Does the miss matter? Would you buy shares of Hanger Orthopedic at current prices? Please weigh in using the comments box below.

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