Japanese technology giant SoftBank Group has agreed to buy asset manager Fortress Investment Group LLC for $3.3 billion in a continued effort to become one of the world’s largest investment firms, says The Wall Street Journal.

Fortress manages about $70 billion in assets–and invests in real estate and private equity—is considered an “alternative-asset manager”. The firm, which was founded in 1998 and led by Randy Nardone, will continue to operate independently in New York with Nardone, Pete Briger and Wes Edens at the helm, says the article.

Companies such as Fortress are considered attractive acquisition targets, according to WSJ, partly because “they are able to charge higher fees and typically require long-term investments from backers.” Revenue at traditional money management firms, on the other hand, has contracted in recent years due to the increased popularity of index funds. The acquisition, says the article, will make SoftBank one of the biggest alternative-asset managers in the world.

The acquisition will also give Softbank access to Fortress’s global network of investors that, “could help it find and structure deals. It also picks up an asset-management back office—compliance, legal and other functions—that could help as it builds out its own investing business.”