Time: 1:30 p.m. - 2:30 p.m., Tuesday, March 24, 2026

Venue: Room 105, Li Dak Sum Building, Guoshun Campus

Speaker: Associate Professor Xueqi Wei (Department of Information Management and Business Intelligence)

Topic: From Crowd-Out to Spill-Over: How the SFPC-CFPC Interaction Drives Third-Party Sellers' Exit–Stay Decisions and Product Variety on B2B Platforms

Abstract: Digital B2B platforms blend substitutive first-party content (SFPC) that competes with third-party sellers and complementary first-party content (CFPC) that empowers them, yet it remains unclear how this mix determines whether third-party sellers exit or persist and, through that behavioral margin, how their product variety evolves. We construct an analytical model in which CFPC lowers seller costs and raises buyer utility while SFPC introduces direct competition as well as spill-over effect, and we test its predictions with a proprietary empirical dataset from a leading Chinese steel-trading platform. The theoretical propositions and empirical results reveal a threshold pattern: when CFPC is weak, an expansion of SFPC drives sellers to exit. The exit response of third-party sellers shrinks their exclusive product categories via negative crowd-out. However, once CFPC surpasses a critical level, the same SFPC expansion encourages sellers to stay via positive demand spill-overs. At this time, third-party sellers' response is fighting back with broadening their exclusive product categories. By unifying SFPC and CFPC in a single framework and pinpointing the tipping point at which SFPC impact flips from crowd-out to spill-over, the study advises platform owners to invest in robust complementary services before scaling self-operated business so as to preserve seller participation and platform's product variety.