Sprint is being acquired by Japanese carrier SoftBank in a deal worth $20.1 billion, the company announced here at a press event in Tokyo. As previously reported, SoftBank will purchase $8 billion in newly-issued shares from Sprint along with $12.1 billion in existing shares, giving the company a 70 percent stake overall. Sprint confirmed late last week that negotiations were ongoing, but it appears that discussions were already at an advanced stage.

The two companies' combined subscriber base will be one of the largest in the world, and will have the third highest mobile service revenue of any company worldwide. In a press release, Sprint CEO Dan Hesse (who was in attendance) said of the acquisition:

“This is a transformative transaction for Sprint that creates immediate value for our stockholders, while providing an opportunity to participate in the future growth of a stronger, better capitalized Sprint going forward. Our management team is excited to work with SoftBank to learn from their successful deployment of LTE in Japan as we build out our advanced LTE network, improve the customer experience and continue the turnaround of our operations.”

Hesse will become the CEO of New Sprint, a newly-constructed company which, between outstanding public shares and the 70 percent stake owned by SoftBank, will control 100 percent of the existing Sprint. As he took the stage, Hesse tried to allay the fears of those in attendance, saying, "we have a lot of lawyers and their core competency is adding words to everything." He moved on to discuss Sprint's market position — it's the third largest postpaid and second largest prepaid operator in the US, before pointing out that the company is first place in revenue growth and average revenue per customer (ARPU) growth. Moving on to the benefits of the deal, the CEO said Sprint will gain an extra $8 billion in equity financing to do things like build out its 4G LTE network and improve its balance sheet. The timing of the investment is key, said the CEO, at a time when Sprint is financially constrained in its ability to improve its networks.

On that note, Hesse commended SoftBank on its successes in Japan, including its rollout of TD-LTE, which he noted is coming to the USA, although he was quiet on Sprint's plans for the 2.5GHz band. However, Sprint is a minority owner and strategic partner of Clearwire, which announced plans to begin rolling out TD-LTE in early 2013. Throughout the presentation, SoftBank CEO Masayoshi Son repeatedly pointed to the benefits of his company's 4G (its branding for TD-LTE) network, saying "speed is everything."

As the presentation drew to a close, Son asked rhetorically how he knew the investment was going to pay off. "Sprint is recovering on its own at an incredible pace," he said, pointing to the company's recent improvements. He then drew a comparison to his company's own acquisitions of Vodafone's Japanese operations and PHS service provider Willcom, pointing out his company's "proven turn-around track record." He also pointed out synergies in devices — including Apple's iPhone and "the very best" Android handsets, and in infrastructure — both companies use Ericsson and Nokia Siemens networking equipment. Before the confirmation it was speculated that SoftBank was pursuing the deal in part to improve its buying power for both, something the CEOs confirmed today.

When faced with questions about the possibility of further acquisitions (say, of the rumored Metro PCS), Son explained that he wanted to dominate the industry, joking, "I'm a man, so I want to be number one. There's always a possibility. There's a possibility we'll acquire Docomo," pointing to Japan's first-place carrier. Hesse then took the mic to add, "consolidation outside of [AT&T and Verizon] is very good for the industry," but failed to give specifics about any hypothetical Metro PCS acquisition. "This deal gives Sprint a better position to participate in the consolidation at some point in the future, but I wouldn't want to speculate," he said.

Sam Byford contributed to this report.