Hybrid platform model: monopolistic competition and a dominant firm
研究了平台通过向卖家收取比例费用控制产品种类和价格，并选择是否自营（混合模式），发现混合平台通过提高卖家费用引导消费者购买自营产品，损害消费者福利，除非边缘进入弹性足够低。
Abstract We model a platform controlling the variety and prices of the products it hosts via a percentage fee on sellers and choosing whether to sell its own products (hybrid mode). We derive a mixed market demand system for differentiated products with monopolistically competitive sellers and a sizeable platform product range. The hybrid platform steers consumers toward its products by charging higher seller fees than pure marketplace. This “insidious steering” intensifies the larger the platform's product footprint. Hybrid mode harms consumers compared to pure marketplace unless fringe entry is sufficiently inelastic.