Affiliated Managers Group, a global asset management company, completed the acquisition of a majority stake in Parnassus Investments, an investment management firm. Financial terms were not disclosed. "Given our longstanding relationship with AMG, and its three-decade history of successful partnerships with independent active investment firms, we are excited about our new partnership. We believe it provides long-term certainty for our clients and enhances the competitive positioning of our business," Benjamin Allen, Parnassus Investments CEO.