It is theoretical and managerial significant to explore the determinants of retailers' decisions between a combined price structure and a partitioned price structure and the effect of their decisions on a manufacturer's product sales in competitive markets. Based on the structure–conduct–performance framework, we reveal that market structure‐related characteristics, such as the number of retailers, the degree of retailer differentiation, whether a dominant retailer in the market, and the number of product substitutes, significantly affect retailers' price structure decisions. Furthermore, more retailers adopting a combined price structure decrease the product sales, although the size of retailers mitigates this effect.