We consider the dual nature of the banking industry and estimate a structural model that examines market power both in the loan market and the deposit market in Argentina. We find that a substantial concentration of the industry led to reduced competition and higher bank profitability, which based on significant reductions in marginal costs despite lower loan rates and higher deposit rates. We also find that the usual assumption of exogenous deposit interest rates provides a downward assessment of the extent of market power in the loan market, and that banks price deposits above their standalone marginal benefit to take advantage of imperfect competition in the loan market.