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: Investors hung up on shares of Atlantic Tele-Network (Nasdaq: ATNI) today, sending them down as much as 16% after the company reported fourth-quarter earnings.

So what: As part of Verizon's (NYSE: VZ) purchase of Alltel, the company was required by regulators to spin off certain assets. AT&T (NYSE: T) picked up the majority of the divested assets, but Atlantic Tele-Network swooped in and grabbed a chunk that included roughly 800,000 wireless subscribers mostly in the U.S. Southeast. As a result of the acquisition -- which just closed midway through last year -- the company's top line soared versus the fourth quarter of 2009. Unfortunately, we can't say the same for profits. Revenue of $194.7 million more than tripled versus last year and topped the $191.3 million estimate from Wall Street. Earnings per share of $0.21 -- which was down versus 2009 -- badly missed the $0.36 expectation.

Now what: The question facing investors is whether they should give the company time to get the newly acquired Alltel assets under control. Management says that the "transition" period will last through the second quarter of this year and that results will look better at that point. I couldn't blame investors for being discouraged though, since they've had to watch the subscriber count from the Alltel acquisition drop by more than 100,000 since the beginning of the June quarter.

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Fool contributor Matt Koppenheffer owns shares of AT&T but does not own shares of any of the other 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 on his RSS feed. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.