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 cellphone service provider MetroPCS (NYSE: PCS) were getting hammered by investors today, losing as much as 14% in intraday trading after the company reported first-quarter results.

So what: Getting right down to the brass tacks, MetroPCS simply didn't deliver during the first quarter. Revenue came in roughly on par with what Wall Street was expecting, but that was on net subscriber additions that were much lower than anticipated. Meanwhile, costs rose, which ate away at profits. Earnings per share finished at $0.06, down from $0.15 last year and well below the $0.17 that analysts were looking for. Adjusted EBITDA -- a form of cash-flow measurement -- fell as well, declining 8% year over year to $262 million.

Now what: MetroPCS' guidance doesn't do much for investors looking for a prediction on annual profit. The company simply reaffirmed its prior view that capital expenditures for 2012 will be between $900 million and $1 billion. Prior to the release of first-quarter numbers, analysts were expecting $0.88 for the full year, though they may revise that now.

Can the company rebound from a rough first quarter? On a sequential basis that's very possible -- after all, just last quarter investors were celebrating better-than-expected numbers. Competition continues to heat up in the industry, though, and looking out at the longer term there will be plenty of challenges ahead for the company.

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