The Efficiency Cost of Market Power in the Banking Industry : A Test of the `Quiet Life' and Related Hypotheses

Traditional concerns about concentration in product markets have centered on the social losses associated with the mispricing that occur when market power is exercised. This paper focuses on a potentially greater loss from market power -- a reduction in cost efficiency brought about by the lack of market discipline in concentrated markets. We employ data from the commercial banking industry, which produces very homogeneous products in multiple markets with differing degrees of market concentration. We find the estimated efficiency cost of concentration to be several times larger than the social losses from mispricing as traditionally measured by the welfare triangle