Big Banks and Macroeconomic Outcomes: Theory and Cross‐Country Evidence of Granularity

Does the mere presence of big banks affect macroeconomic outcomes? We develop a theory of granularity for the banking sector by modeling heterogeneous banks charging variable markups. Using data for a large set of countries, we show that the banking sector is indeed “granular,” as the right tail of the bank size distribution follows a power law. We demonstrate empirically that the presence of big banks, measured by a high degree of market concentration, is associated with a positive and significant relationship between bank‐level credit growth and aggregate growth of credit or GDP.