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 - Get Report) , Public Service Enterprise Group (PEG - Get Report) , Medtronic (MDT - Get Report)  and International Business Machines  (IBM - Get Report) . Fellow FedEx director Susan Schwab also sits on four boards, including Caterpillar (CAT - Get Report) , Boeing (BA - Get Report)  and Marriott International  (MAR - Get Report) . Suzanne Nora Johnson serves on the board of directors at Pfizer  (PFE - Get Report) , Visa (V - Get Report) , American International Group  (AIG - Get Report)  and Intuit  (INTU - Get Report) . Former CEO of Lucent Technologies, Patricia Russo is a director for Merck (MRK - Get Report) , General Motors (GM - Get Report) , Arconic  (ARNC - Get Report)  and is the Chairman of the board for Hewlett Packard Enterprise  (HPE - Get Report) .