This study examines the causal effects of bank size on banks' survival, asset quality and leverage. Two forces drive these effects: increasing returns to scale derived from banks' expertise and competition. The first enables bigger banks to survive competition better, have higher asset quality and be more leveraged. It drives banks into a race for expansion. This race toughens competition between banks, which edges out small banks and may worsen all banks' asset quality. Consequently, the banking industry will be dominated by a small number of highly leveraged banks. In this study, financial intermediation arises endogenously and co-exists with direct finance.