Abstract

With the aim to measure and monitor systemic risk, we present some topological metrics for the interbank exposures and the payments system networks. The evolution of such networks is analyzed, we draw important conclusions from the systemic risk's perspective and propose a measure of interconnectedness. Additionally, we suggest non-topological measures to describe individual behavior of banks in both networks. The main findings of this paper are: the structures of the payments and exposures networks are different (in terms of connectivity); the topology of the exposures network changed after the collapse of Lehman Brothers, whereas the structure of the payments network does not; the proposed measure of interconnectedness can be used to determine the importance of a bank in terms of connectivity. Finally, we found that interconnectedness of a bank is not necessarily related with its assets size but it is linked to the contagion it might cause.

Highlights

  • Despite the importance of systemic risk in the international financial regulatory arena, authorities have failed to reach an agreement on a common widely accepted definition for this concept

  • The data obtained to build the payment system network is relatively easier to access by the authorities and regulators, as generally the central banks are in charge of the management of Large Value Payment Systems

  • To differentiate between inner and outer strength is important, as we are interested in determining which bank is lending the most in the network. Such differentiation is important in the context of systemic risk because a bank can play a specific role in the network; that is, a bank can be very important as a lender or as a borrower in the interbank exposures network and it is important from the regulators’ perspective as the failure of such institutions would have different repercussions depending on the role played in the network

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Summary

Introduction

Despite the importance of systemic risk in the international financial regulatory arena, authorities have failed to reach an agreement on a common widely accepted definition for this concept. The data obtained to build the payment system network is relatively easier to access by the authorities and regulators, as generally the central banks are in charge of the management of Large Value Payment Systems This is not the case for the interbank exposures network. Some relevant findings are reported in this work on dynamic aspects of two well recognized networks for the Mexican banking system: the payment system flows and the interbank exposures networks. In this work we found that the interbank exposures network posses different connectivity to the payments system flows network, with the latter being more intensively connected. The proposed measure of interconnectedness captures the dynamics of the connectivity relevance of a node in terms of low/high value payments or as lender/borrower in the payments system or the interbank exposures network respectively.

Network models and systemic risk
Payment systems
Network formation models
Notation and measures
Topological measures
Clustering coefficient
Other measures
Preference index
Centrality measures
Degree centrality
Betweenness centrality
A principal components unified measure of centrality
Global and individual measures
Individual measures
Centrality and systemic risk
Robustness of centrality measures
Bottom k vertices
Correlation
Overlap k
Findings
Conclusions and further work
Full Text
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