Keller started his banking career with the Swiss Bank Corporation in New York, then spent time in the Swiss Diplomatic Service, where he was assigned to the Swiss Observer’s Office to the United Nations, the Federal Political Department in Berne, and the Swiss delegation to EFTA in Geneva. He joined Lombard, Odier & Cie in 1961, and has been the partner responsible for institutional clients since 1970, and senior partner from 1990 to 1994. He retired from Lombard, Odier & Cie in 1995. He was also a member of the International Committee of the Red Cross and served as its vice president. Until the end of 2017, he was chairman of the board of trustees of “Europaeum,” an association of leading European Universities initiated by Oxford University. Keller studied law at the University of Geneva and international relations at Yale University, where he obtained the degrees of master’s of arts and doctor of philosophy.