Sprint, led by CEO Dan Hesse, has been bleeding customers for years, and is in the middle of a costly network modernisation project which involves upgrading its Sprint network at the same time as it decommissions the Nextel iDen network - once famous for its walkie-talkie style feature - that it bought in 2005.
"The challenge is not access to capital," said Roe. "The challenge is that they're sub-scale (much smaller than rivals AT&T and Verizon) and going through a very challenging network transition."
Japanese media said buying Sprint - which competes in the United States against Verizon Wireless and AT&T Inc - would make it cheaper for Softbank to procure smartphones and other mobile devices.
"The asset (Sprint-Nextel) represents the only way for a potential new entrant to get a national presence immediately in the U.S., especially given T-Mobile's recent signalling that it will reinvest in the market and no longer seems willing to sell itself near-term," said Wells Fargo analyst Jennifer Fritzsche in a note.
Sprint may be attractive to Softbank as it has a majority interest in Clearwire Corp, which owns 2.5 Ghz spectrum, Fritzsche said, adding that Softbank is one of few global carriers that has an active 2.5GHz TDD / LTE network.
Fritzsche noted regulators would likely look favourably on a deal that would bring in an outside international player to the United States.
Japanese companies made a record 642 cross-border deals last year, according to Thomson Reuters data. Buoyed by a stronger yen, the value of all outbound deals rose to $69.5 billion, up 81 percent from 2010, also a record.
The biggest foreign acquisition by a Japanese company to date was Japan Tobacco's 1.8 trillion yen buy of British-based tobacco firm Gallaher in 2007.
Sprint is considering whether to make a counter-bid for smaller rival MetroPCS Communications, which this month agreed to merge with Deutsche Telekom's T-Mobile USA, a source told Reuters this week.
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