Its broad holdings include large mobile and broadband subsidiaries, Internet properties such as Yahoo Japan and the Japanese UStream, and big investments in foreign firms such as U.S. social game provider Zynga and China's Alibaba Group. Softbank was founded in 1981 by its current CEO Masayoshi Son, a charismatic entrepreneur who had repeatedly made, and won, multi-billion dollar bets with his company in the past.
Softbank's history as a mobile operator only dates to 2006, when it purchased the struggling Japanese unit of Vodafone. Softbank immediately unleashed a barrage of advertising that included international superstars such as Brad Pitt and offbeat commercials featuring talking cats and aggressive contract plans that set off a price war.
It was also the first of Japan's big three operators to embrace smartphones and made another successful gamble in agreeing to Apple's strict purchasing and profit-sharing requirements to become Japan's exclusive iPhone provider until last year. Since entering the mobile business in April of 2006, Softbank has more than doubled its subscriber base to 30 million, a period in which the Japan's overall number of subscribers has increased only 40 percent.
Softbank remains Japan's third-largest mobile carrier, but earlier this month announced it has agreed to acquire smaller domestic rival eAccess, which could vault it to No. 2 in terms of subscriber contracts.
Rumors of a deal have been swirling since last week, when the companies said they were in negotiations after a host of news reports said Softbank would soon take a significant share of Sprint.
With additional reporting by Mikael Ricknäs in London.