Ryan is selling a “significant minority equity interest” in the Dallas tax services firm to one of Wall Street’s most prominent investment firms, Ares Management Corp.

The undisclosed investment amount, announced Thursday, boosts Ryan’s valuation to $2.5 billion, according to a joint statement from Ryan and Onex Corp., an earlier investor in the company.

The companies didn’t address whether Ryan’s management team, Onex or Ares holds the controlling stake. The transaction with Ares, which had $325 billion in assets under management as of March 31, is expected to close later this year.

Toronto-based Onex spent $317 million in 2018 to buy a 42% stake in Ryan, which the company said at the time gave it a $1.1 billion valuation.

Ryan, which generated an estimated $630 million in revenue in 2020, describes itself as the largest firm devoted exclusively to business taxes. It boasts over 18,000 clients in 60 countries and employs 3,500 people.

“Ares is an excellent partner for our firm due to their experience helping great companies drive technology transformations and long-term growth,” said CEO and co-founder G. Brint Ryan in a statement. “We have been on a growth trajectory with recent strategic acquisitions, expansions of several key practice areas, and the addition of some of the world’s most respected companies to our already impressive client roster.”

Ryan’s goal is to build a global tax brand and it’s been growing aggressively through acquisitions.

This year alone, it has closed deals for Boston-area property tax consulting firm Greystone Property Tax Advisors, British-based tax reclaim specialist Catax, property tax consulting firm Marvin F. Poer and Company, historic tax credits consulting firm MacRostie Historic Advisors and Houston-based motor fuels excise tax specialist Tax Advisory Services Group.