There has been a growing interest in the analysis of the asymmetries in competition in literature. Empirical evidence of its existence in the Spanish diaper market suggests us to study the source of these asymmetries and implications for the brand price decisions and more specifically, in the analysis of the brand's competitive position. Literature suggests that aggregation process of heterogeneous consumers in brand preferences or characteristics of the utility function can explain asymmetric competition. The results do not allow the rejection of any of these causes in the analyzed market. The paper also makes methodological contributions suggesting a different approach to aggregate consumers on the basis of their homogeneity on brand preferences.