[Photo:  Masayoshi Son with Donald Trump;  by Hilary Swift for NYTimes]

Japanese conglomerate SoftBank, which is known for its technology and telecommunications holdings, is acquiring the Fortress Investment Group, an American private equity giant that oversees around $70 billion in assets. SoftBank will be paying $3.3 billion for Fortress, a premium to the company’s public market value of $2.3 billion.

The acquisition is intended to bolster SoftBank’s enormous new endeavor - a $100 billion technology investment fund that threatens to roil the private equity world. And it plays into the promise made by SoftBank founder, Masayoshi Son, to Donald Trump to create jobs in the United States.

The move also highlights the immense ambitions of SoftBank’s brash founder, Mr. Son. The mogul, who is one of Japan’s richest men, has sought to shake up the American telecommunications industry. Over the past three decades, SoftBank has become one of Japan’s most formidable technology companies. It is perhaps best known for its telecommunications empire, which stretches from Japan to Sprint in the United States.

Rajeev Misra, a former top derivatives expert at Deutsche Bank, … formulated the strategy to purchase Fortress, a prominent private equity firm with a specialty in investing in distressed assets,. He has taken a leading role in setting investment strategy for the vision fund.

The Japanese company now oversees assets under management of $170 billion, making it one of the largest private investors in the world after the Blackstone Group, which manages about $330 billion.