As investors grow increasingly critical of Wall Street and its offerings, companies with business models that require high levels of debt are receiving no mercy. Clearwire's (Nasdaq: CLWR) capital-intensive launch of its broadband wireless network has been taking on more and more skeptics as losses continue to flow.

Clearwire disappointed Wall Street in its fourth-quarter earnings today, reporting high customer defection rates and a lower revenue outlook for the coming year. Shares dropped as much as 13% in the morning before recovering this afternoon to a decline of 5%. Clearwire noted that it expected 2008 revenues of $205 million to $215 million, a growth rate of only 36% to 42%. 

Clearwire mentioned a strong competitive response from cable companies and others, which appears to have taken hold. Monthly churn is up to 2.4% this quarter, above the 1.9% level last year. Cable companies such as Comcast (Nasdaq: CMCSA) and Time Warner Cable, as well as telcos Verizon (NYSE: VZ) and AT&T (NYSE: T), certainly will not let their customers go without a fight. Verizon even recently introduced new pricing plans for its wireless broadband service, aiming to snag and retain more customers.

But Clearwire is making strides in its business evolution -- 24 of its 46 domestic markets have turned positive on an adjusted EBITDA basis -- and the company believes early market financials show that the business model is scalable. Clearwire also holds cash and equivalents of more than $1 billion on the books, giving it a nice cash cushion to continue to develop new markets.

In addition, Clearwire plans to deploy a fully mobile version of the WiMAX broadband platform later this year. But all eyes are still on just who in the industry will cover Clearwire's back in WiMAX. Sprint Nextel (NYSE: S) isn't a surety any more, although Clearwire says it's still in active discussions with its one-time partner. WiMax fans Intel (Nasdaq: INTC) and Motorola (NYSE: MOT) have already sunk hundreds of millions in the nascent platform, but some investors are clearly betting that Clearwire is on its own at this point.

With lots of money still in the bank, we're in the early chapters of a long book for Clearwire. I expect the company to be around for the long haul, but shares will certainly be volatile going forward, just as they have been in the past.

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