[Photo: Fortress Co-Chairs Pete Briger and Wes Edens]

The 3 leaders of Fortress Investment Group will cash in a combined $1.39 billion from the sale of the alternative-asset manager to SoftBank Group. Co-Chairmen Pete Briger and Wes Edens own stakes worth $510 million and $511 million, respectively, while CEO Randy Nardone’s Class A shares are valued at $371 million. The trio have agreed to remain in charge of the business and invest half of their after-tax proceeds from the sale in the company’s funds.

Buying Fortress is an effort by Japan’s SoftBank to bring investment talent in-house as founder Masayoshi Son works to create a $100 billion Vision Fund with a consortium of backers, making the billionaire one of the world’s biggest technology investors. The deal for Fortress is for both “human capital” and “investment potential,” according to a person with knowledge of the matter, who asked not to be identified because SoftBank’s strategic details aren’t public.

Fortress was founded in 1998 by Edens, Nardone and Robert Kauffman. Briger was hired from Goldman Sachs in 2002. The 3 founders became billionaires when the firm went public in 2007, but shares have slumped by almost 2/3’s since the listing after the company faced volatile performance during the financial crisis and struggled to explain its value to public shareholders.

The payout from the sale to SoftBank will mark the 2nd big windfall for the Fortress partners. Edens, Briger and three other principals extracted $1.7 billion in dividends and private stock sales from Fortress before it went public.