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 utility and industrial equipment manufacturer ESCO Technologies (NYSE: ESE) shot up as much as 17% in intraday trading after the company reported fiscal first-quarter results.

So what: The first quarter was a big bounce for ESCO. After growth slowed to a halt in fiscal years 2009 and 2010, it reappeared with a vengeance this quarter as revenue jumped 42% from the first quarter of 2010 and earnings per share increased from $0.02 to $0.40. Both revenue and earnings for the quarter trounced the expectations of Wall Street analysts.

Now what: The company maintained its outlook for 2011, noting that sales to PG&E (NYSE: PCG) will continue to slow as that contract winds down. Management sees both 2011 revenue and earnings per share increasing by 10% to 15%. Looking further ahead, ESCO is hoping that its smart grid offerings will help drive continued growth. However, with shares currently trading at 21 times fiscal 2011 earnings expectations, investors better be pretty sure about healthy growth if they're buying today.

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Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.