: Abstract
Every financial crisis raises questions about how the banking market structure affects the real economy. Although low bank concentration may lower markups and foster bank risk-taking, controlled banking concentration systems appear more resilient to financial shocks. We use a nonlinear dynamic stochastic general equilibrium model with financial frictions to compare the transmissions of shocks under different competition and concentration configurations. Oligopolistic competition and concentration amplify the effects of the shocks relative to monopolistic competition. The transmission mechanism works through the markups, which are amplified when banking concentration is increased. According to financial stability and social welfare objectives, the desirable banking market structure is determined. Depending on policymakers' preferences, the banking concentration of five to seven banks balances social welfare and bank stability objectives