Abstract: Online start-ups are the engines of growth, innovation, and wealth creation on electronic marketplaces. Although it is expected that the growth patterns of online start-up swill be different from their offline counterparts, the extant research has not paid sufficient attention to this unique group of firms. In this paper, the typical growth patterns and characteristics of start-up online sellers are explored.Drawing upon Penrose's growth theory, it is theorized that start-up online sellers' growth pattern can be conceptualized by the growth trajectory and the growth volatility. Moreover, their choice of product categories will also shape their growth patterns, leading to diverse performance.Based on a longitudinal clustering analysis, three types of growth trajectories are identified, namely "accelerating", "constant", and "decelerating". Consolidating with the volatility levels(high/low), typology of six types of growth patterns is formulated. The Chi-square test shows that the growth patterns are significantly associated with both the sellers'product types (search/experience good), initial product categories, and their primary product categories. In addition, the ANOVA and Kruskal-Walls analyses show that seller performance (sales and rating levels) significantly differs between growth patterns. The "accelerating/high volatility" sellers' performance is the most prominent distinctive one.Our findings contribute to firm growth pattern research by exploring the context of online start-ups. Moreover, our work provides implications for e-commerce platforms to evaluate the start-up online sellers and supportspecialized service according to their growth patternp/>

Key words: online start-ups, growth patterns, growth trajectory, growth volatility, product category, seller performance