Shares in Leap Wireless (LEAP) rose 8.6% Thursday, its second day of gains after reporting a return to profitability, boosted by a spectrum sale to Verizon Wireless (VZ). Still, Leap's stock is down 35% in 2012, and it's viewed as a possible takeover target. That speculation cooled off recently as one possible suitor, MetroPCS Communications (PCS), agreed to merge with T-Mobile USA. Here was IBD's story. On Thursday, Sprint Nextel (S) cancelled a