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 communications equipment specialist ADTRAN (Nasdaq: ADTN) slumped 11% on Wednesday after its quarterly results came in below Wall Street expectations.

So what: ADTRAN's disappointing results -- earnings fell 43% while revenue was down slightly -- mark its third straight quarter of bottom-line decline, reinforcing fears over its profitability going forward. A tough spending environment, coupled with rising costs, continue to pressure the company's margins, giving investors little hope for a near-term turnaround.

Now what: I'd look into this pullback as a possible entry point for patient Fools. "Decreasing visibility leaves us cautious for the near term," said CEO Tom Stanton in a statement, "but we are confident that our strong customer alignment and increasing global footprint will deliver long term growth for the company." With the stock hitting a new 52-week low today and trading at a cheapish forward P/E of 11, buying into that optimism might just pay off over time.

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