Since 2002 I have been a professor in the Computer and Information Science Department at the University of Pennsylvania, where I hold the National Center Chair. I have secondary appointments in the department of Economics, and in the departments of Statistics and Data Science and Operations, Information and Decisions (OID) in the Wharton School. I am the Founding Director of the Warren Center for Network and Data Sciences, where my Co-Director is Rakesh Vohra. I am the faculty founder and former director of Penn Engineering's Networked and Social Systems Engineering (NETS) Program, whose current directors are Andreas Haeberlen and Aaron Roth. I am a faculty affiliate in Penn's Applied Math and Computational Science graduate program. Until July 2006 I was the co-director of Penn's interdisciplinary Institute for Research in Cognitive Science.
Since June 2020, I am an Amazon Scholar, focusing on fairness and privacy in machine learning and related topics within Amazon Web Services.
I have worked extensively in quantitative and algorithmic trading on Wall Street (including at Lehman Brothers, Bank of America, SAC Capital and Morgan Stanley; see further details below). I often serve as an advisor to technology companies and venture capital firms, and sometimes invest in early-stage technology startups. I occasionally serve as an expert witness or consultant on technology-related legal and regulatory cases.
I am an elected Member/Fellow of the National Academy of Sciences, the American Academy of Arts and Sciences, the Association for Computing Machinery, the Association for the Advancement of Artificial Intelligence, and the Society for the Advancement of Economic Theory.
