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: Security fell asleep on the job this morning and shares of Brinks (NYSE: BCO) were robbed, losing 19% of their value.

So what: Revenue grew 13% in the fourth quarter to $997 million, but non-GAAP earnings per share fell to $0.56 from $0.80 a year ago. Analysts had expected earnings of $0.63 per share on $1.05 billion in revenue.

Now what: Higher security costs affected margins leading to the lower-than-expected revenue. The company is hoping that a rapidly growing business in Latin America will help performance in the future. Revenue there grew 34% over last year, driven by an acquisition the company made in Mexico. Shares trade at just 12.7 times adjusted earnings per share for 2011, and considering the company's growth I think that's an attractive value in this business.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.