Sprint Nextel (NYSE:S) has found a Japanese sugar daddy.

We've known for a couple of weeks that America's third-largest wireless network provider has been talking to Japanese counterpart Softbank about a cash-infusion deal.

Today, a press release from Softbank shows that the talks have resulted in a solid agreement. It's not an outright acquisition, but a very large equity investment that would give Softbank 70% ownership of Sprint. The deal is expected to breeze through regulatory reviews and close in mid-2013.

If given the go-ahead on both sides of the Pacific, Softbank will pay $8 billion up front for a slug of freshly minted Sprint shares, and then take $12 billion of existing stock off the hands of current shareholders. The company will pay $7.30 per share, a 27% premium to Friday night's closing price.

Sprint shares are surging nearly 10% on the pre-market news, but Clearwire (UNKNOWN:UNKNOWN) is jumping 25%. That company lives and dies with Sprint, but lives much closer to the edge of insolvency, so this deal is seen as a lifesaver for both Sprint and Clearwire. A Sprint on more stable financial footing may even try to acquire Clearwire outright.

Fool contributor Anders Bylund has no positions in the stocks mentioned above. The Motley Fool has no positions in the stocks mentioned above. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.