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 railcar manufacturer American Railcar Industries (Nasdaq: ARII) were going off the tracks today, falling as much as 15% in intraday trading after the company announced its fourth-quarter results.

So what: In the headline for its quarterly earnings press release, American Railcar touted "strong shipments and results." The market appears to have seen it differently.

To be fair, the press release headline is far from misleading; on an absolute basis, American Railcar's year-over-year performance was pretty awesome. Total revenue more than doubled to $197 million, while earnings per share of $0.24 reversed a $0.37-per-share loss from the year before. The results were driven by railcar shipments of 2,170, up from 950 in the final quarter of 2010.

Unfortunately, during the quarterly earnings dance, investors only jump for joy if results are better than what they expected. In this case, the average EPS estimate from Wall Street was $0.27, so the company's tally fell short.

Now what: It's certainly a good thing to see production ramping up for American Railcar, but for investors who want to get an idea of what the coming quarters are going to look like, it makes sense to take the temperature of orders coming in and the backlog the company has stacked up. Both look very promising. The company noted that orders for all of 2010 were 10,710, the highest level since 2005. And at the end of the year, its backlog was 6,530 railcars, up from just 1,050 at the end of 2010.

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