14 people serve on the board of directors of four S&P 500 companies at the same time. Of those 14, four are women, according to BoardEx data. BoardEx is a business unit of TheStreet. American physicist Dr. Shirley Ann Jackson serves on the board of four publicly traded companies: FedEx (FDX) , Public Service Enterprise Group (PEG) , Medtronic (MDT) and International Business Machines (IBM) . Fellow FedEx director Susan Schwab also sits on four boards, including Caterpillar (CAT) , Boeing (BA) and Marriott International (MAR) . Suzanne Nora Johnson serves on the board of directors at Pfizer (PFE) , Visa (V) , American International Group (AIG) and Intuit (INTU) . Former CEO of Lucent Technologies, Patricia Russo is a director for Merck (MRK) , General Motors (GM) , Arconic (ARNC) and is the Chairman of the board for Hewlett Packard Enterprise (HPE) .