Japan’s SoftBank (Tkyo: 9984) announced plans to acquire 70 percent of Sprint-Nextel Corp. (NYSE: S) in a complex deal that will reward Sprint shareholders with $12 billion in cash.

The deal would make Tokyo-based SoftBnk, Japan’s No. 3 mobile carrier as well as a content provider, in control of the No. 3 U.S. telecommunications carrier.

Sprint, of Overland Park, Kan., hasn’t reported a quarterly profit since 2010 and had been seeking outside assistance.

The deal will require approval from regulators on both sides of the Pacific. Pending Oks, the deal is expected to close in the middle of 2013, the companies said.

Sprint CEO Dan Hesse will remain as head of Sprint, following a complex transaction under which SoftBank will pump cash into a new company, New Sprint, that will purchase current Sprint shares for $5.25 apiece. Later, they’ll have the option to get $7.30 for each share of New Sprint.

In pre-market activity, Sprint shares rose 15 cents to $5.87.

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