Affiliated Managers Group, Inc. 's AMG ratings have been affirmed by Moody's Investors Service. However, the company's rating outlook has been downgraded to negative from stable. The senior unsecured rating has been affirmed at A3, while the junior subordinate rating is at Baa1. Concurrently, Affiliated Managers' new junior subordinated notes maturing in 2060 have been assigned a rating of Baa1.