The purpose of this work is the structural modelling of price competition in a product-differentiated industry in which many firms of varying size compete across many independent small markets, with the target of identifying price behaviour. We apply it to model competition among the more than 79 banks that were active in the Spanish loans market during the period 1983–1991, using micropanel data. A model in which national banks (as opposed to regional and local banks) fully internalize their cross-rate effects in pricing is selected as the model that best fits the data. Our framework allows us to estimate the dead-weight loss due to market power, and to decompose it assessing the part attributable to price coordination.Publicad