Time: 3:30 p.m. - 5:00 p.m., Tuesday, March 31, 2026

Venue: Room 303, Starr Building, Guoshun Campus

Host: Professor Lingfang Li

Speaker: Associate Professor Muxin Li (Shanghai Institute of Mathematics and Interdisciplinary Sciences)

Topic: Gatekeepers and Self-Preferencing: Incentives and Welfare Trade-offs in Two-sided Markets

Abstract: We study a two-sided platform where a dominant gatekeeper supplies both a primary product and a complementary ancillary service. By degrading outcomes for users of rival ancillary services, the gatekeeper engages in cross-market self-preferencing. Our theoretical model identifies when such behavior raises or lowers welfare, depending on buyers' and sellers' preferences and the platform's pricing instruments. Analyzing a recent antitrust case against Google, we show that remedies targeting only one side can misalign incentives between different user groups, reducing welfare. Counterfactual simulations highlight when alternative behavioral or structural interventions realign incentives and improve market efficiency.

Bio：Muxin Li has been an Associate Professor jointly appointed at Fudan University and the Shanghai Institute of Mathematics and Interdisciplinary Sciences (SIMIS) since 2026. She was previously a Research Fellow at Bocconi University, Italy, from 2021 to 2025, with visiting positions at Paris SciencesPo in 2024 and the European Commission in 2025. Li earned her PhD in Economics from Indiana University Bloomington in 2019 and was a postdoctoral researcher at UCLouvain, Belgium from 2019 to 2021. Her research focuses on Industrial Organization, particularly antitrust analysis, digital platform competition, and mergers. Her work has appeared in leading journals, including American Economic Journal: Microeconomics, International Journal of Industrial Organization, and Review of Industrial Organization. She has received several awards in competition economy, such as the CIVICA Grant (2023), CPI Young Researchers Award (2024), first place in the Young Talent Competition (2025), the NYU NET Institute Grant (2025), and the Modigliani Grant (2025).