Diversification and Systemic Bank Runs

36 Pages Posted: 18 Jul 2018 Last revised: 26 May 2019

See all articles by Xuewen Liu

Xuewen Liu

University of Hong Kong (HKU) - Finance Area, Faculty of Business and Economics

Date Written: April 2019


Diversification through pooling and tranching securities was supposed to mitigate creditor runs in financial institutions by reducing their credit risk, yet many financial institutions holding diversified portfolios experienced creditor runs in the recent financial crisis of 2007-2009. We present a theoretical model to explain this puzzle. In our model, because financial institutions all hold similar (diversified) portfolios, their behavior in the asset market is clustered: they either sell their assets at the same time or collectively do not sell. Such clustering behavior reduces market liquidity after an adverse shock and increases the probability of a panic run by creditors. We show that diversification, while making the financial system more robust against small shocks, increases the possibility of a systemic crisis in the case of a larger shock; diversification, inducing stronger strategic complementarities across institutions, makes a self-fulfilling systemic crisis (multiple equilibria) more likely. Because individual institutions either over-diversify or under-diversity in the competitive equilibrium compared with the social optimum, there is room for regulation.

Keywords: Diversification, market liquidity, panic runs, systemic crises, coordination risk

JEL Classification: G01; G21; D82; D53

Suggested Citation

Liu, Xuewen, Diversification and Systemic Bank Runs (April 2019). Available at SSRN: https://ssrn.com/abstract=3208008 or http://dx.doi.org/10.2139/ssrn.3208008

Xuewen Liu (Contact Author)

University of Hong Kong (HKU) - Finance Area, Faculty of Business and Economics ( email )

Pokfulam Road
Hong Kong

HOME PAGE: http://web.hku.hk/~xuewenl/

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