This paper shows that the impact of market structure on bank deposit interest rates is complex. Both market size structure and multimarket bank presence have independent effects on rates. There is evidence that mid-size banks were more aggressive competitors than other banks, but that the effect of market structure on deposit rates has evolved over time, with mega-banks recently becoming more aggressive competitors. This may be related to the growth of mega-banks in many markets. These findings have implications for existing theories of deposit pricing and, by extension, antitrust policy in banking.

Market size structure refers to the distribution of shares of different size classes of local market participants, where the sizes are inclusive of assets both within and outside the local market. We apply this new measure of market structure in two empirical analyses of the US banking industry to address concerns regarding the effects of the consolidation in banking. Our quantity analysis of the likelihood that small businesses borrow from large versus small banks and our small business loan price analysis that includes market size structure as well as conventional measures yield very different findings from most of the literature on bank size and small business lending. Our results do not suggest a significant net advantage or disadvantage for large banks in small business lending overall, or in lending to informationally opaque small businesses in particular. We argue that the prior research that excluded market size structure may be misleading and offer some likely explanations of why our results differ.