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 Neutral Tandem (Nasdaq: TNDM) were stuck in reverse today as they slipped as much as 19% in intraday trading after a disappointing fourth-quarter earnings report.

So what: When does growth not get investors excited? When that growth doesn't lead to more profit. For the fourth quarter, Neutral Tandem's revenue -- boosted in large part by the acquisition of Tinet -- leapt 43% from the prior year. Billed minutes jumped 25% to 29.9 billion. However, earnings per share for the quarter clocked in at $0.18, down from $0.31 last year and well short of the $0.29 that Wall Street was looking for. Adjusted EBITDA -- which allows the company to add back healthy amounts of share-based compensation -- was up slightly, but the adjusted EBITDA margin plummeted from 50% to 36%.

Now what: To truly bum out investors, it also takes a lower-than-expected forecast, and Neutral Tandem provided that as well. For 2011, management gave guidance for adjusted EBITDA of $91 million to $95 million. According to Capital IQ, analysts on average had projected EBITDA of nearly $99 million. To be sure, there are some bright spots for this Motley Fool Hidden Gems pick. The company reported increased cash flow for 2010, and it still sports a debt-free balance sheet. And based on 2010 earnings per share of $0.97, the stock trades at less than 15 times earnings -- not overly cheap, but not expensive either. However, it would seem that the company has some work ahead to jump-start its bottom line.

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