Coupon promotion and inventory strategies of a supplier considering an e-commerce platform's omnichannel coupons

Omnichannel coupons that are issued by an e-commerce platform and can be used either online or offline have been gaining popularity with the emergence of omnichannel retailing to provide consistent shopping experiences for consumers. This paper investigates the coupon promotion and inventory strategies of a supplier that operates the online-only, store, and BOPS channels considering a platform's omnichannel coupons in the post-pandemic era because consumers are more price-sensitive. The conditions for joint promotional activities where both parties issue coupons are explored. Newsvendor models under six strategies are constructed based on the combination of the two players' coupon promotion strategies to capture the aggregate demand uncertainty. Utilizing the game theory, the optimal decisions of the platform and the supplier are obtained under different strategies. The results indicate that the equilibrium outcome varies from online joint promotion to omnichannel joint promotion that the platform issues omnichannel coupons and the supplier distributes online coupons to only the platform offers omnichannel coupons with the increase in the supplier's loss from returns when consumers' valuation difference is relatively large in a general heterogeneous scenario. Moreover, compared to unilateral promotion, joint promotion allows consumers to receive deeper price discounts and reduces the costs of promotional entities. As the supplier's return loss expands, the platform tends to switch from offering traditional online coupons to issuing omnichannel coupons, resulting in an increase in store inventory.