In this work we examine the relationship between satisfaction, comparison and customer retention in transactions involving clients and suppliers of retail banking services. We conducted 522 structured interviews with clients of a bank, covering ten different kinds of services, such as credit operations, insurance, savings and investment funds. We bring the theoretical support of Information Economics and Transaction Cost Economics to understand why clients decide to stay with their current banking services supplier. Results from multiple regression analysis support the hypothesis that postulate the existence of a moderate mediation relationship between satisfaction, complexity and the continuity of the transaction. Furthermore, these results indicate that the customer, who usually has limited knowledge in finance, is susceptible to the complexity of the offer in such a way that this complexity seems to have a higher impact on retention than satisfaction; which is partially opposite to what others have found in Brazil. Key words: customer retention, satisfaction, switch cost, moderate mediation, retail banking services.