If Sprint Nextel is seriously weighing a bid for MetroPCS, its shareholders didn’t appear enthusiastic. Bloomberg News reported Sprint was weighing a potential challenge to T-Mobile USA’s proposed merger with MetroPCS. The deliberations are at an early stage, the report said. MetroPCS shares closed up 3.7 percent, at $12.69. Sprint has been hunting for more wireless spectrum as it builds its Long Term Evolution service, which offers the high speeds new smartphones need.