Abstract: Blockchain technology is reshaping various industries with its features of decentralization, immutability, openness and transparency. In the retail industry, blockchain applications are in full swing. Walmart, an offline retail giant, has urged its suppliers to join the platform and “put” many fresh products on the blockchain platform. By the end of 2020, Walmart China's traceable fresh meat had accounted for 50% of total packaged meat sales, 40% of traceable vegetables, and 12.5% of traceable seafood. The online Chinese retail giant JD.com has also built a blockchain platform. According to the data shown in JDDigits in 2020, JD's blockchain platform brought about an overall sales growth of 9.97% in 2020. Among them, the sales of nutrition and health products increased by 29.4%, those of maternal and infant milk powder by 10.0%, and those of fresh products by as much as 77.6%. The data shows that the application of blockchain enhances the brand image of retailers and makes consumers have more trust in products on the chain, thereby increasing their willingness to purchase. However, according to the author's research on offline supermarkets (Wal-Mart, Olé boutique supermarkets, etc.), some products are on the chain, but others are not on the chain. In addition to the reasons why suppliers are not willing to put the products on the chain because of the unknown costs and benefits on the chain, for these retailers who have built blockchain platforms, they express their doubts about the products on the chain during the survey: Should they put as many products on the blockchain platform as possible? What's more, these retailers often sell substitute products with different brands at the same time, so putting substitute products on the chain may affect the competition between products and eventually affect sales and revenues of retailers. Therefore, retailers who have already built blockchain platform, should discreetly consider which products to be placed on the blockchain platform and how to set retailing prices. In this paper, we aim to answer the following questions: (1)Considering products with different consumer preferences, what products should the retailer choose to put on the blockchain? (2)How should the retailer price multi-products in the background of blockchain? (3)What is the value of blockchain in multi-product pricing?
We consider a monopoly retailer who has built a blockchain platform. The retailer can choose two substitute products to put on the blockchain and decide their prices. We develop analytical models to explore the impact of blockchain on the retailer's pricing strategies and profits. We consider cases with zero or positive variable cost of deploying blockchain, and cases with putting only one product or both products on the blockchain. In sum, we have six models, including three models with zero cost (BN/NB/BB) and three models with positive cost (BNC/NBC/BBC), where “C” indicates the positive cost, “BN” indicates that the first product is put on the blockchain while the second is not, and “NB/BB” likewise. The model NN in which there is no blockchain at all is introduced as a benchmark.
Our main findings are as follows: 1.(Zero variable cost of blockchain). If the retailer decides to put on only one product (model BN or NB), she should choose a more popular product and set a higher price than other products. The more popular product, even with a higher price, still has higher demand than the less popular product, thanks to the blockchain. Compared with the case of no blockchain (baseline model NN), we find that the less popular product's price also increases. However, its demand remains the same, hence the overall profit of the retailer increases. We call it the spillover effect of the blockchain value. The product without being on the blockchain can also indirectly benefit from the blockchain. Moreover, the retailer should put both products on the blockchain. 2.(Positive variable cost of blockchain). If the retailer puts only one product on the chain (i.e., the BNC or NBC model), compared with the baseline model NN, counterintuitively, the product without being on the chain brings more profits while the product on the chain may not. Moreover, the spillover effect of blockchain value is more evident—the demand for the product without being on the chain increases. When the market potential growth brought by the blockchain is large enough and the variable cost is small enough, it is profitable for the retailer to put products on the chain. Besides that, when the cost is in the appropriate range but still high, when the cost is low (high), the retailer would better put the more (less) popular product on the chain.

Key words: monopoly retailer, blockchain, multi-product pricing, consumer preference

摘要： 考虑一个已搭建区块链追溯平台的垄断型零售商(如区域性的大型超市),其可选择将销售的两种产品加入此平台(简称“上链”)以提升产品的市场潜力。零售商需要决定哪种产品上链及各自的零售价以最大化其总利润。通过求解多产品定价模型,分析对比不同上链情况下两种产品的需求、利润贡献以及零售商总利润的变化,得出零售商定价以及产品上链的策略。研究发现存在一种“区块链价值的溢出效应”,即不仅上链产品的利润贡献增大,未上链产品也能享受区块链带来的价值提升,其利润贡献也增大。当无区块链成本时,零售商将产品上链总是有利的,并且消费者偏好的产品上链带来的利润更大,而两种产品都上链更好。但是,当有区块链成本时,零售商选择产品上链不一定获利。而如果一定要给某一产品上链,则当上链成本低(高)时,零售商应选择给消费者更(不)偏好的产品上链,并且此时“区块链价值的溢出效应”会比无区块链成本时更强。研究结论为垄断决策者在区块链背景下的多产品定价问题提供了有益的管理启示。

关键词: 垄断零售商, 区块链, 多产品定价, 消费者偏好