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 Leap Wireless (Nasdaq: LEAP) leaped as high as 13% today after Bernstein Research analyst Craig Moffett upgraded the wireless service specialist from market perform to outperform.

So what: Along with the upgrade, Moffett offered a new price target on the stock of $12, representing a whopping 70% worth of upside to yesterday's close. The stock has been battered over the past few months -- down more than 50% since the start of July -- on unexpectedly high churn rates, so today's rally serves as a much-needed boost for embattled Leap bulls.

Now what: I wouldn't get too excited over the stock just yet. While Leap -- as well as close rival MetroPCS (NYSE: PCS) -- may be benefiting somewhat from an industrywide trade-down, its high debt load, steadily declining operating margins, and long history of inefficiency are just too worrisome for a long-term commitment. More short-term pops are certainly possible, especially with all the uncertainty surrounding the proposed AT&T (NYSE: T) and T-Mobile deal, but betting big on them doesn't seem prudent.

Interested in more info on Leap? Add it to your watchlist.

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.