The author thanks advisors Bart Bronnenberg, Peter Reiss, and Stephan Seiler for exceptional supervision and constant support; Paulo Albuquerque, Kristina Brecko, Robert Donnelly, Liran Einav, Pedro Gardete, Brett Gordon, Wesley Hartmann, Avery Haviv, Han Hong, Megan Hunter, Przemyslaw Jeziorski, Anja Lambrecht, Suraj Malladi, Navid Mojir, Sridhar Moorthy, Sridhar Narayanan, Andres Perlroth, Peter Rossi, Navdeep Sahni, Paulo Somaini, Raluca Ursu, Xavier Warnes, and Ali Yurukoglu, as well as seminar participants at Stanford University, Institut Européen d’Administration des Affaires (INSEAD), Tilburg University, London Business School, Harvard University, Northwestern University, University of Washington, Rochester University, New York University, University of California Berkeley, and University of California Los Angeles (UCLA), for insightful comments and suggestions that have greatly improved the paper; Julie Williamsen, Sean Kaneshiro, and Wonhee Lee for helping me access Comscore data; and Robyn Lockwood for teaching me to write well, although it will take a lifetime to master what she taught me. All errors are my own.