Katz Graduate School of Business. He is a world-renowned expert on social media and digital marketing who taught social media strategy for over five years throughout the United States, Europe, and Asia, and has worked with companies such as American Express, Colgate-Palmolive, Delta Air Lines, and Google, among many others. At the Katz School, Dr. Stephen teaches digital marketing and social media marketing to MBA students and to senior-level managers and executives in the school’s Executive MBA Worldwide program.