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 optical equipment maker Ciena (Nasdaq: CIEN) fell 12% today after the company released earnings.

So what: Revenue was $433.3 million, higher than analysts' estimates of $421.9 million, and a loss of $0.14 per share was better than the $0.16 loss that was expected. But then we got a look at outlook, and with analysts expecting second quarter sales of $438.5 million, management only sees it in the range of $415 million to $435 million.

Now what: As fellow Fool Anders Bylund pointed out today, this may be nothing more than a market correction after a long hot streak for Ciena. Considering that quarterly earnings were stronger than expected, I wouldn't be panicking today on a little weakness from the outlook. With that said, if I'm a buyer I may wait for a longer correction before jumping in. With earnings out of the bag, there may not be much to drive the stock higher in the short term.

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