David Nadler has been an academic, a consultant, and a senior executive. He served on the faculty at the Graduate School of Business, Columbia University. In 1980, he founded the Delta Consulting Group and was CEO of the firm for 20 years. In 2000, he managed the acquisition of Delta by Mercer, a Marsh & McLennan Company, and continued to run Mercer Delta through 2005. In 2007, he was appointed vice chairman of the Marsh and McLennan Companies, a global professional services firm.