In 1971, he was named to the top position at Morgan Guaranty and served during a period of historic change for banking that was marked by greater flexibility and expanded service, rising to become chairman of the board and chief officer of both Morgan Guaranty Trust Company of New York and its parent holding company, J.P. Morgan & Co., Incorporated. He led the institution with imagination, vision, and discretion, taking it boldly into new approaches and new fields of service, while exercising the prudence that is essential to successful banking.
Patterson served as a member of the Federal Advisory Council of the Federal Reserve System as well as a trustee of the Carnegie Endowment for International Peace, the Alfred P. Sloan Foundation, the Memorial Sloan-Kettering Cancer Center, and the University of Chicago.