 He then completed three advanced degrees from the Fletcher School of Law and Diplomacy at Tufts University—a masters in international studies, a masters in international economics from the Graduate Institute of International Studies, Geneva and a doctorate in international economics from Tufts.Before joining McKinsey, Thoman worked in finance at Citicorp and Exxon.Thoman became a longtime protégé of Louis V. Gerstner, Jr., when they first met at McKinsey & Company, and they subsequently worked together at American Express, RJR Nabisco, and IBM.