Hierarchical contagions in the interdependent financial network

We model hierarchical cascades of failures among banks linked through an interdependent network. The interaction among banks includes not only direct cross-holding, but also indirect dependency by holding mutual assets outside the banking system. Using data extracted from the European Banking Authority, we present the interdependency network composed of 48 banks and 21 asset classes. Since interbank exposures are not public, we first reconstruct the asset/liability cross-holding network using the aggregated claims. For the robustness, we employ 3 reconstruction methods, called "Anan, Hal‚a and Maxe". Then, we combine the external portfolio holdings of each bank to compute the interdependency matrix. The interdependency network is much more dense than the direct cross-holding network, showing the complex latent interaction among banks. Finally, we perform macro-prudential stress tests for the Euro- pean banking system, using the adverse scenario in EBA stress test as the initial shock. For different reconstructed networks, we illustrate the hierarchical cascades and show that the failure hierarchies are roughly the same except for a few banks, reflecting the overlapping portfolio holding accounts for the majority of defaults. Understanding the interdependency network and the hierarchy of the cascades should help to improve policy intervention and implement rescue strategy.