Online retailing has seen steady growth over the last decade. According to the Digital Commerce (formerly Internet Retailer) analysis of the US Commerce Department's year-end retail data, online sales constituted 16% of all retail sales in 2019, and is forecast to reach higher levels in the next years due to the impact of COVID-19. For an online retailer, one of the most important decisions is the products' display positioning as it plays a crucial role in shaping customers' shopping behavior. Empirical evidence abounds. Baye et al. [2] find that a consumer's likelihood of purchasing from a firm is strongly related to the order in which the firm is listed on a webpage by a search engine. In the online advertising industry, it has been widely observed that ads placed higher on a webpage attract more clicks from consumers [1]. Given the importance of product ranking positions, the key question for online retailers is how to rank the products to maximize the revenue.