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 piping specialist Insituform Technologies (Nasdaq: INSU) were getting hammered by investors today, falling as much as 16% in intraday trading on heavier-than-average volume.

So what: For those running a company, here's a surefire way to upset your investors: Tell them that you're not going to earn as much money as you thought. If you want proof that this works, you don't need to look any further than Insituform's shares today. The company announced "updated" guidance today, saying that largely because of a weak market for its North American Sewer Rehabilitation business, the company will now earn between $1.30 and $1.40 per share for the year. That compares to previous guidance of $1.75 to $1.90 per share and analyst expectations of $1.70.

Now what: Considering the fact that analysts' views were lower than management's previous guidance and that the stock (even prior to today's drop) was trading at a low multiple of previous expectations, it seems that investors had a more pessimistic view than management. Still, the cut that was announced today was pretty hefty, and the market's reaction shouldn't be too surprising. For investors that want to look on the bright side, though, the company is still comfortably profitable, has a strong balance sheet, and its businesses outside of the troubled North American Sewer Rehabilitation are performing well.

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The Motley Fool owns shares of Insituform Technologies. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.

Fool contributor Matt Koppenheffer does not have a financial interest in 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 Facebook. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.