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 aerospace components maker Esterline Technologies (NYSE: ESL) are down 13% (and counting) in intraday trading today.

So what: But why? I mean, sure, Esterline missed Street expectations for third-quarter revenues by a bit. But as CEO Brad Lawrence pointed out, "all three of Esterline's segments posted sales improvements." Plus, the company hit the analysts' earnings target on the nose, earning $1.21 per share from continuing operations.

Now what: The problem, it seems, is not what Esterline earned, but what it says it will earn over the rest of this year. After taking into account a "one-time" charge to earnings, management says it's now on track to report net profit for the year of about $4.50 per share -- down from previous expectations that had ranged as high as $4.95. My guess is that's the news that has investors so worried.

If so, though ... I can't say as I agree with them. Even $4.50 per share would be enough to give this company a 14 P/E ratio -- right in line with consensus expectations of 14% annual long-term earnings growth. That's almost by definition a fair price to pay.

Will investors agree that Esterline is now safe to buy? Add it to your watchlist and find out.

Fool contributor Rich Smith does not own (or short) shares of any company named above. The Motley Fool has a disclosure policy.

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