This paper investigates a platform service supply chain composed of a single supplier and a service platform that not only resells products but also may serve as an intermediary that connects the supplier to consumers directly. The service platform can improve the performance of the retail channel by investing in retail service. The supplier decides whether to encroach on the retail market by opening a direct channel on the platform. We analyze the interaction between the platform's service investment strategy and the supplier's encroachment decision by establishing a game model. We then compare the payoffs of the firms under different service investment strategies and find that the platform benefits from supplier encroachment in several cases. The benefit not only comes from the reduction of the double marginal effect but also from the share of profits that the supplier earns from the direct channel. A spillover effect can be observed in the platform's service investment. The spillover effect causes the increased profits generated by such investment to transfer to the supplier, ultimately resulting in that the service investment by the platform does not necessarily create more revenue for itself, but increases the supplier's profit. Results indicate that a platform's investment in retail service is not always intended to prevent supplier encroachment. In some cases, such investment is meant to induce a supplier to encroach through the platform. Robustness analysis shows that the main results derived in the basic model hold. Managerial implications are then discussed and provided.

本文研究了一个平台服务供应链，该平台服务供应链由单个供应商和一个服务平台组成，该服务平台不仅可以转售产品，还可以充当将供应商与消费者直接连接的中介。该服务平台可以通过投资零售服务来提高零售渠道的绩效。供应商通过在平台上打开直接渠道来决定是否入侵零售市场。我们通过建立博弈模型来分析平台的服务投资策略与供应商的侵占决策之间的相互作用。然后，我们比较了不同服务投资策略下公司的收益，发现该平台在某些情况下会受益于供应商的入侵。收益不仅来自双重边际效应的减少，还来自供应商从直接渠道获得的利润份额。可以在平台的服务投资中观察到溢出效应。溢出效应使这种投资所产生的增加的利润转移给供应商，最终导致平台的服务投资不一定为其本身创造更多的收入，而是增加了供应商的利润。结果表明，平台在零售服务上的投资并不总是旨在防止供应商受到侵害。在某些情况下，此类投资旨在诱使供应商蚕食该平台。稳健性分析表明，基本模型中得出的主要结果成立。