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 chip design specialist Mentor Graphics (Nasdaq: MENT) were getting hammered today, falling as much as 16% in intraday trading after the company reported fiscal-first-quarter earnings.

So what: Every once in a while a big stock move leaves me scratching my head. And that's exactly the case with Mentor's shares today. The stock is down big on heavy trading, but the results that the company reported looked pretty darn good.

For the quarter, revenue rose 8% year over year and, at $248 million, it was just short of the $255 million that analysts were expecting. However, the bottom line looked much better than expected. On a non-GAAP basis, earnings per share increased 50% from last year, to $0.30. Wall Street was looking for just $0.25.

Now what: But it was more than just better-than-expected, past-quarter earnings. The company also raised its full-year earnings estimate by $0.05 to $1.37 -- easily above the average analyst estimate of $1.33. It also reaffirmed its previous guidance of $1.1 billion in full-year sales.

Investors' harsh reaction today could have something to do with the missed sales estimates -- there's only so far that cost cutting can get a company if its customers aren't buying. However, shareholders should be encouraged by the fact that full-year revenue estimates were kept steady. Though, even if we take the soft first-quarter sales into account, the harsh reaction today seems overdone.

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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.