Peter Raupach

Centrality-based Capital Allocations

This paper looks at the effect of capital rules on a banking system that is connected through correlated credit exposures and interbank lending. Keeping total capital in the system constant, the reallocation rules, which combine individual bank characteristics and interconnectivity measures of interbank lending, are to minimize a measure of systemwide losses. Using the detailed German Credit Register for estimation, we find that capital rules based on eigenvectors dominate any other centrality measure, saving about 15 percent in expected bankruptcy costs.

Pitfalls in the Use of Systemic Risk Measures

We examine pitfalls in the use of return-based measures of systemic risk contributions (SRCs). For both linear and non-linear return frameworks, assuming normal and heavy-tailed distributions, we identify non-exotic cases in which a change in a banks systematic risk, idiosyncratic risk, size or contagiousness increases the risk of the system but lowers the measured SRC of the bank. Assessments based on estimated SRCs could thus produce false interpretations and incentives. We also identify potentially adverse side effects: A change in a banks risk structure can make the measured SRC of its competitors increase more strongly than its own one.