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 auto-component manufacturer Gentex (Nasdaq: GNTX) got clobbered by investors today, falling as much as 13% in intraday trading before closing down 10.8%.

So what: Despite the staggering drop for the stock, it wasn't all bad news for Gentex. The company reported results from its fourth quarter and showed that revenues were up 17% from a year ago, to $260 million. However, that growth got progressively less exciting the further down the income statement you move. Gross margins declined from a year ago from 35.8% to 34.7%. Net income growth of 10% was well short of the sales gains, and earnings per share grew an even slower 8%.

But what particularly frustrated investors today is that these results all fell short of expectations. Analysts had been looking for $0.30 in per-share profit on $273 million in sales.

Now what: Though management touted the fact that the company hit $1 billion in sales for the first time in 2011, it also noted that the year had some definite challenges as the earthquake and tsunami in Japan and the flooding in Thailand affected the auto-industry supply chain.

Will 2012 be a better year? Without similar supply-chain disruptions, it certainly could be, and the company's guidance of 15% to 20% year-over-year sales growth for the first quarter certainly suggests a good start to the year. At the midpoint, that forecast would top analysts' current average sales estimate. However, profitability isn't expected to quickly bounce back, as management said it sees first-quarter gross margins in line with the fourth quarter's level.

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