A model to analyse financial fragility

Summary. This paper sets out a tractable model which illuminates problems relating to individual bank behaviour, to possible contagious inter-relationships between banks, and to the appropriate design of prudential requirements and incentives to limit ‘excessive’ risk-taking. Our model is rich enough to include heterogeneous agents, endogenous default, and multiple commodity, and credit and deposit markets. Yet, it is simple enough to be effectively computable and can therefore be used as a practical framework to analyse financial fragility. Financial fragility in our model emerges naturally as an equilibrium phenomenon. Among other results, a non-trivial quantity theory of money is derived, liquidity and default premia co-determine interest rates, and both regulatory and monetary policies have non-neutral effects. The model also indicates how monetary policy may affect financial fragility, thus highlighting the trade-off between financial stability and economic efficiency.Received: 6 November 2003, Revised: 6 October 2004 JEL Classification Numbers: D52, E4, E5, G11, G21.C.A.E. Goodhart, P. Sunirand, D.P. Tsomocos: We are grateful to T.F. Bewley, S. Bhattacharya, F. Hahn, C. Mayer, H.S. Shin and seminar participants at the Bank of Austria, Bank of England, Bank of Norway, Bank for International Settlements, Brown University, the 7th Annual Macroeconomic Conference, Crete, EcoMod-IIOA International Conference, Brussels, the 2nd Oxford Finance Summer Symposium and Nuffield, Oxford, the Hong Kong Institute for Monetary Research, Purdue University, the University of Birmingham, the VI SAET Conference, Rhodes, Yale University, and especially an anonymous referee and H.M. Polemarchakis for helpful comments. The views expressed are those of the authors and do not necessarily reflect those of the Bank of England. Correspondence to: D.P. Tsomocos