From Bloomberg: Sprint Nextel plans to end a network-sharing agreement with LightSquared, two people familiar with the matter told Bloomberg News.

Sprint and LightSquared struck an 11-year deal to share network expansion costs and equipment in June provided LightSquared secure regulatory approvals for its wireless service by December. Though Sprint pushed the deadline back to March 15, it doesn’t plan more extensions, said the people, who wouldn’t be identified because the information isn’t public.

The loss of Sprint would fuel concerns about the viability of LightSquared and mark another setback for Phillip Falcone. The hedge fund manager has invested about $3 billion from his Harbinger Capital Partners in LightSquared in an effort to create a national wireless carrier to compete against AT&T and Verizon.

Terry Neal, a LightSquared spokesman, and Scott Sloat, a Sprint spokesman, declined to comment. Lew Phelps, a spokesman for Falcone, said he had no immediate comment.