Softbank Corp. aims to strengthen its wireless holdings in the United States as Sprint Nextel Corp. said it reached a deal to acquire 100 per cent ownership of Clearwire Corp. for $2.2 billion US. Sprint, which said in October it would be acquired by Japanese mobile carrier Softbank, said in a release Monday it will purchase its remaining 50 per cent stake in Clearwire for $2.97 US per share and “strengthen its position and increase competitiveness in the U.S. wireless industry.” Sprint, based in Overland Park, Kansas, said it intends to use Clearwire’s 2500 MHz spectrum as the frequency is migrated to LTE. Clearwire is based in Bellevue, Wash. “Today’s transaction marks yet another significant step in Sprint’s improved competitive position and...