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: Clearwire Corp. (Nasdaq: CLWR) dropped 10% in intraday trading today after Bloomberg published an article suggesting the company may be facing competitive pressure at partner Sprint Nextel (NYSE: S).

So what: Clearwire sells "4G" wireless network capacity to Sprint. Cellular providers are investing huge sums in 4G, the newest and fastest wireless networking equipment, to get the high-speed capacity needed to support pricy data services for Web surfing on mobile devices such as smartphones and tablets.

Now what: LightSquared Inc. is in talks with Sprint about working together to build out a 4G network. Should this occur, Sprint would be able to play Clearwire off against LightSquared on pricing, and Clearwire could lose a share of Sprint's business. With Clearwire's history of losses and the potential downside risk from competitive pressures, investors need a strong bull counterthesis to like this stock.

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