主讲人：沈吉 副教授（北京大学光华管理学院）

主持人：熊泽源 助理教授（辽宁大学中国经济研究院）

嘉宾介绍：何超 副教授（辽宁大学中国经济研究院）

时间：2026年10月9日（周五）  14：30-16：00（北京时间）

地点：辽宁大学蒲河校区经济学部大楼547会议室

语言：中文/英文

摘要：Social interaction is now often part of the consumption of digital products: in online games, fitness apps, and live streams, users interact while they consume, and interaction enhances or dampens a user’s enjoyment depending on whom she encounters. The firm that sells such a product prices something whose value its own users shape. We ask how the firm should price when the price selects not only who participates but whom every participant meets. In a dynamic model with forward-looking consumers, we characterize the stationary equilibrium and compare participation, the elasticity of demand, profit, and the optimal price with a no-interaction benchmark. In the main model, where a consumer’s willingness to pay and her value as a partner are aligned, interaction never lowers the firm’s profit and raises it whenever upward influence exists, even when downward influence dominates; for weak interaction, whether the optimal price falls depends on the distribution of consumer valuations rather than on the direction of influence. In an extension in which willingness to pay and value as a partner are separate characteristics, the price can drive out the very users who make interaction valuable, and interaction can lower profit. We show that whether interaction raises the firm’s profit is decided not only by how positive it is but, more importantly, by whom the price keeps.

主讲人简介：

沈吉，在伦敦政治经济学院获得金融学博士学位，现任教于北京大学光华管理学院。研究兴趣主要在资产定价理论，数字经济等。论文发表散见于《经济研究》《世界经济》《金融研究》和Review of Financial Studies、Management Science、Journal of Banking and Finance等国内外学术期刊。