Abstract: This article investigates the motivations and basic logic behind platforms implementing “exclusive dealing”， and analyzes the impact of “exclusive dealing” on social welfare and market competition landscape
During the rapid growth phase of startups，the primary goal of platforms is to expand user base rather than profit Therefore，platforms do not actively implement “exclusive dealing” However，as the gap among platforms widens，the entire market gradually transitions to a stable and mature stage of monopolistic competition among leading platforms Platforms in dominant positions typically use “exclusive dealing” to generate profits or exclude competitors Specifically，in situations of relatively intense competition，although dominant platforms implementing “exclusive dealing” may lose some multiplatform merchants，they will also cause disadvantaged platforms to lose a higher proportion of multiplatform merchants，ultimately leading to an expansion in the relative merchant ratio between dominant and disadvantaged platforms，and a squeezed market survival space of disadvantaged platforms In situations of relatively mild competition，dominant platforms may proactively reduce their number of merchants through “exclusive dealing” while increasing the fees for merchants In this process，multiplatform merchants and some merchants exclusively living on dominant platforms may migrate to disadvantaged platforms due to costbenefit considerations
Through the use of Hotelling model and numerical simulations，we find that: the implementation of “exclusive dealing” by dominant platforms harms the welfare of consumers，merchants，and overall social welfare，and in situations of relatively intense competition，it leads to a higher proportion of merchant loss for disadvantaged platforms and reduces their profits However，in situations of relatively mild competition，“exclusive dealing” may also have positive effects While enhancing the profits of dominant platforms，it may also increase the profits and number of merchants of disadvantaged platforms
According to the conclusions above，we suggest that regulatory authorities should examine the different impact of “exclusive dealing” on social welfare in different competitive environments，and accordingly improve regulatory concepts and optimize regulatory measures

Key words: platform economy, exclusive dealing, welfare analysis, network externalities, market dominance

摘要： 本文采用霍特林模型和数值模拟方法，揭示了不同竞争环境下平台实行“独家交易”的动机和底层逻辑，以分析其对社会福利和市场竞争格局的影响。研究发现：（1）在高速成长阶段，平台出于扩大规模、扭亏为盈的考虑，一般不会实行“独家交易”。（2）在平稳成熟阶段，优势平台出于提升收益或扩大相对商户规模的目的，有动力单方面实行“独家交易”；而劣势平台出于持续盈利、平稳发展以及维持商户规模（或相对商户规模）的考虑，一般不会主动实行“独家交易”。（3）“独家交易”会损害消费者、商户的福利及社会总福利，并在竞争相对激烈时使劣势平台面临更高比例的商户流失并降低其收益。（4）在竞争相对缓和时，“独家交易”也可能在提升优势平台收益的同时，增加劣势平台收益和商户数量，防止市场格局由“垄断竞争”演变成“完全垄断”。监管部门应考察不同竞争环境下平台“独家交易”对社会福利的差异化影响，并据此完善监管理念、优化监管措施。

关键词: 平台经济, 独家交易, 福利分析, 网络外部性, 市场支配力