Should banks be allowed to do business across borders? The answer is not obvious. For one, it is beneficial that they have the opportunity to better diversify their risks, but they can do this without having to open branches in other states or countries. The counterpart is that doing business elsewhere increases opportunities for adverse shocks. Finally, regulatory competition in an international banking market leads to a large systemic risk.
Dirk Schoenmark and Wolf Wagner try to sort this out in the case of Europe and come to the conclusion that it depends. They argue that Germany and the UK are well diversified and thus can sustain cross-border banking, even though there appears to be overexposure to the US, as exemplified by the large negative consequences in Europe of the recent crisis in the US. For the countries on the fringes of Europe, though, there seems to be very poor diversification. Indeed, these economies seem to be very dependent on a few large foreign banks, and consequences could be dire if they run into difficulties or decide to pull out.
This analysis is entirely based on asset shares and thus diversification. This neglects a major advantage of foreign banks: they bring lending capital that would otherwise not be available. The case for cross-border banking is thus understated in this paper.