Assessing the Common Ownership Hypothesis in the US Banking Industry

The U.S. banking industry is well suited to assess the common ownership hypothesis (COH), because thousands of private banks without common ownership (CO) compete with hundreds of public banks with high and increasing levels of CO. This paper assesses the COH in the banking industry using more comprehensive ownership data than previous studies. In simple comparisons of raw deposit rate averages we document that (i) private banks do offer substantially more attractive deposit rates than public banks, but (ii) the deposit rates of public banks are similar in markets without CO where a single public bank competes only with private rivals, and in markets with CO where multiple public banks compete with each other. Panel regressions of deposit rates on the profit weights implied by the COH are generally consistent with the COH if only quarter FEs (without other controls) are included but not if bank-quarter FEs are included. Estimates with bank-quarter FEs are "precise zeros" with 95% CIs suggesting that the threefold rise in CO among public banks between 2005 and 2022 moved their deposit rates by less than a quarter of a basis point in either direction. To assess the COH along non-price dimensions we also estimate the effect of CO on deposit quantities, and find that the estimates are also not consistent with the COH.