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 wireless services provider Leap Wireless International (Nasdaq: LEAP) are losing their connection with shareholders today, down as much as 12% earlier in the trading session, following an update on its fourth-quarter subscribership.

So what: Very similar to MetroPCS Communications, which reported subscriber growth of 197,000 today, Leap Wireless guided the Street to an expected gain of 175,000 customers for the fourth quarter. With estimates ranging from as low as 115,000 to as high as 195,000 Leap's growth seems pretty decent. For the year, Leap added approximately 413,000 customers to finish the year with 5.9 million subscribers. "So what's wrong?" you might be wondering. The company's churn rate is expected to be 3.7% to 3.9%, significantly higher than anyone had anticipated.

Now what: Companies like Leap and MetroPCS don't exactly have an easy go of things -- especially right now. With the release of the iPhone 4S still fresh in consumers' minds, rival AT&T has cleaned up by selling more than 6 million units in the first two months of the fourth quarter. Verizon Wireless, the joint venture of Verizon and Vodafone Group, is also expecting strong fourth-quarter iPhone sales, but at the expense of its gross margin. For a company like Leap to add subscribers in an environment where technological shifts can occur on the drop of a dime is encouraging. Still, with Leap expecting very steep losses in 2012 and the company buried under $3.2 billion in debt, I'd advise passing on the stock despite today's sizable haircut.

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