Sprint Nextel Corp. and Clearwire Corp. said Friday that they had canceled their plan to combine the high-speed wireless networks they are building.
The breakup is a blow to Clearwire, which already has a network in some parts of the country based on the WiMax technology. Sprint's network, using the same technology, would have complemented Clearwire's coverage.
Shares of Clearwire fell $4.54, or 25%, to $13.49 after sliding as low as $13.03, an all-time low. The Kirkland, Wash.-based company went public in March at $25 a share.
The breakup casts a cloud over the future of WiMax, which is seen as a cost-effective alternative to cellular broadband. Reston, Va.-based Sprint is the largest carrier to embrace the technology.