关键词: 双目标, 网络零售商, 利润分成比例, 消费者剩余

Abstract: On e-commerce sites such as Walmart marketplace and Dangdang.com, retailers offer their competitors the opportunity to sell the same products on their sites. This behavior is called “e-tailer referral”. It is often assumed that companies will make optimal decisions by raising trade barriers and gaining more market share in a competitive market. However, one-way or two-way referral between retailers can promote implicit collusion, jointly setting higher retail prices and thus gaining higher profits, but the behavior harms the consumers' surplus. Nowadays, as the corporate social responsibility (CSR) increases, more and more retailers consider their own interests as well as consumer surplus, transforming into dual-purpose companies. This raises a new question: does the dual-purpose retailer change its referral strategy among other retailers?
We consider a duopoly market consisting of two e-retailers (Retailer 1 and Retailer 2), who mitigate the long-standing fierce competition by providing links to their competitors' products in their own stores. Four different strategy combinations can occur: both with referral, one without referral but the other with referral, one with referral but the other without referral, and both without referral. In addition, with an increase in corporate social responsibility in the market, retailers pay more attention to the change in consumer surplus in their decision-making process rather than just pursuing their own profit maximization. When a retailer incorporates consumer surplus into its decision making, defining it as a dual-purpose retailer, it will be a question to think about what kind of referral strategy the dual-purpose retailer will adopt. Based on previous research, we categorize consumers into three groups, G1, G2, and G. G1 and G2 are partially informed consumers who are only aware of their corresponding retailers, and G is the fully informed consumers who are aware of both retailers. The Hotelling model is used to characterize the utility that a consumer obtains from purchasing products in different markets from which demand is derived.
First, the equilibrium referral strategy is affected by the profit-sharing ratio in a benchmark model of retailers without dual purpose. As the profit-sharing ratio increases, the equilibrium referral strategies are: one without referral, one without pure strategy Nash equilibrium, and both with referral. This is because when the profit-sharing ratio is low, they cannot compensate for the loss of profits due to referral; when the profit-sharing ratio is medium, retailers prefer to adopt the same referral strategy; when the profit-sharing ratio is sufficiently high, retailers will choose referral strategy and jointly set higher prices. Second, in the single dual-purpose retailer model (Retailer 1 is dual-purpose), compared to the benchmark model, as Retailer 1 reduces retail price taking into account consumer surplus, it forces Retailer 2 to reduce its price as well. Both the demands of Retailer 1 and Retailer 2 will increase when only Retailer 1 implements referral but decreases under another referral scenario. At the same time, as Retailer 1's consumer surplus concerns increase, Retailer 1's willingness to choose the referral strategy decreases, and the space for both with referral strategy decreases, but for both without referral strategy increases, because high retail prices under the referral strategy are detrimental to consumer surplus. Finally, in both the dual-purpose retailer models, the fact that retailer 2 is also a dual-purpose retailer leads to a further reduction in retail prices for both retailers. In addition, consumer surplus will be optimal in equilibrium when both retailers are dual-purpose, followed by single dual-purpose, and the lowest when there is no dual-purpose retailer.

Key words: dual-purpose, e-tailer referral, profit-sharing ratio, consumer surplus