The continuous growth of e-commerce leads to the emergence of a new supply chain model known as community group buying, which is advantageous to address the inefficiencies and higher costs of intermediate processes. However, its appearance results in fairness concerns for other participating merchants. In this regard, we construct a model with two suppliers, one wholesaler, and two retailers for three different scenarios of the initial status, fairness neutrality, and fairness concern, and comparatively analyze the game equilibria in different scenarios. The results show that the profits of the suppliers and the wholesaler significantly increase after the online retailer enters into the market, whereas the offline retailer's profit has multiple prospects. The online retailer's entry into the marketplace weakens the market position of the offline retailer and significantly erodes its pricing advantage. Additionally, our paper finds that the entry of the online retailer is beneficial for social welfare, and investment conversion efficiency on the platform construction is the core factor for the improvement of social welfare. On the contrary, the influence of fairness concern on social welfare is quite limited and only affects the internal distribution of benefits.

Supply chain greening has become an important direction for sustainable development. This paper develops a two-stage game model involving a traditional manufacturer, a green manufacturer, and a retailer, to investigate the fairness concerns of the green manufacturer in a supply chain. Different from previous fairness concern models that focus on a single comparison relationship, this study incorporates both horizontal fairness concern with the competing traditional manufacturer and vertical fairness concern with the retailer into a unified framework for green supply chains. The results show that when traditional and green consumers hold equal market shares, the demand and profit of the green manufacturer are consistently higher than those of the traditional manufacturer, although this advantage diminishes as green R&D efficiency decreases. Moreover, increasing bidirectional fairness concern reduces the greenness of green products and significantly affects the retailer’s profit, while its impact on manufacturers’ profits is relatively limited. The effects of bidirectional fairness concern on product pricing depend on green R&D efficiency and the competitive relationship between green and traditional products. Based on these findings, managerial insights are provided for supply chain participants.