The Diversification and Cost Effects of Interstate Banking.

This study examines recent interstate bank geographic diversification inside the United States. More than 80 holding companies that gradually evolved into interstate banking companies were tested for significant linkages to risk and efficiency indicators. The study finds that while geographic expansion frequently is associated with increases in risk, when banking firms were grouped by threshold levels of geographic diversification more highly diversified interstate banks appear to achieve reductions in risk exposure and operating costs. The study's results suggest the spread of interstate banking may change the industry's risk and cost profile significantly with profound implications for the future of the deposit insurance fund. Copyright 1996 by MIT Press.