The Impact of Market Growth on Delivery Speed: Evidence from JD.com

This paper examines how rapid market expansion in e-commerce platforms can generate disparities in customer experience, focusing on fulfillment speed as a key operational outcome. Using granular order-level data from JD.com, we document a robust negative relationship between customer tenure and delivery time; newer customers systematically receive slower deliveries than legacy customers. We show that this lifetime effect is not explained by differences in customer preferences, order composition, or SKU availability but instead reflects frictions in the supply chain network. In particular, newer customers are more likely to reside in recently entered or logistically peripheral areas, where fulfillment infrastructure is less developed. Even after controlling for routes and urban context, the delivery gap persists, driven primarily by longer last-mile segments. We further show that regions with more centralized hub-and-spoke network structures exhibit larger disparities in delivery performance, whereas more decentralized configurations yield more uniform outcomes across cohorts. Together, these findings highlight the operational challenges of matching fulfillment capacity to demand in a spatially expanding market and underscore the need to align logistics strategy with patterns of customer growth.