QUALITY COMPETITION IN PLATFORM MARKETS: EVIDENCE FROM THE U.S. VIDEO GAME INDUSTRY CARMELO CENNAMO † Bocconi University Dept. of Management & Technology Roentgen, 1 20136 Milano, Italy (39) 0258363459 (phone) carmelo.cennamo@unibocconi.it JUAN SANTALO ‡ IE Business School Chair, Dept. of Strategy Maria de Molina, 12 28006 Madrid, Spain (34) 91-5689600 (phone) juan.santalo@ie.edu First Version: January 2010 This Version: June 2010 † The author thanks the Spanish MICINN for the generous support through research project number ECO2008-02333-RWC and the PhD Program and the Strategy Department of IE Business School for generous funding on this project. The author also thanks Manuel Becerra, Daniel Fernandez, Luis Gomez- Mejia, and Fernando Suarez for their comments on earlier drafts of the article. ‡ The author thanks financial support from Madrid Regional Government’s research Grant # S2007/HUM- 0413 and the Spanish Ministry of Education’s research Grant # SEJ2007-67582-C02-01.