By Ken Schachter

Shares of Craig McCaw’s WiMAX startup Clearwire bolted higher in its Nasdaq debut Thursday, sagged, then regained ground in afternoon trading.

The Kirkland, Washington, company raised about $600 million as its IPO priced at $25, the top of its range. Shares bolted to $27.25, up 9 percent, at the open, but by late morning had dipped below the offering price before leveling off.

The Clearwire IPO advances the WiMAX vision of wireless broadband service stretching coast to coast. Stitching together the network and deploying next-generation mobile WiMAX equipment, however, is expected to be a tall order, consuming hundreds of millions of dollars more than were raised in the IPO.

In fiscal 2007 alone, the company said it expects to burn through about $800 million, not counting spectrum acquisition.

“Telecom and infrastructure buildup deals went away after the dot-com implosion,” said Tom Taulli, author of Investing in IPOs. “This indicates a willingness to take on some risk. You’re not going to see many of these deals, but it’s interesting that—especially if you have a really good team—the public is willing to take a flier.”

Lucrative Market

In July, Clearwire withdrew a planned $400-million IPO, instead taking a $900-million cash infusion from backers Intel and Motorola. Semiconductor giant Intel sees a potentially lucrative market in supplying WiMAX chips, while Motorola is supplying the wireless equipment mounted on cellular towers for Clearwire’s buildout.

Mr. McCaw, Clearwire’s chairman, founded the company in 2003. In 1997, he sold his company, McCaw Cellular Comunications, to AT&T for $11.4 billion. He later revived wireless carrier Nextel, which merged with Sprint in a $35-billion deal in 2004.

Mr. Taulli said Clearwire is another high-risk bet for Mr. McCaw.

“There’s competition. The cost of marketing is not cheap. Maintaining customers is not cheap,” he said.

WiMAX (worldwide interoperability for microwave access) is a standard designed to extend the range of broadband wireless from Wi-Fi’s 300 feet to several miles, depending upon the geography.

In February, AT&T, in a concession to gain approval of its merger with BellSouth, sold Clearwire a chunk of wireless spectrum for $300 million (see Clearwire: $300M for Spectrum).

“I think that AT&T spectrum deal was very important for them,” Mr. Taulli said. “It was expensive, but it’s all about getting as much coverage as you can.”

A syndicate of 10 underwriters, including Merrill Lynch, Morgan Stanley, and J.P. Morgan, snapped up $36 million on the IPO.

“They had a good day too,” Mr. Taulli said.