Systemically Important Accounts, Network Topology and Contagion in Artis

Abstract

The purpose of this study is the investigation of the relevance of network topology for the stability of payment systems in the face of operational shocks. The analysis is based on a large number of simulations of the Austrian large-value payment system ARTIS that quantify the contagion impact of operational shocks at participants' sites. The analysis uncovers that only few accounts are systemically important. We also find that network indicators at the node level can have some explanatory power. Their explanatory power is higher when the analysis focuses on the contagion measured by the number of banks with unsettled payments than in the case of the measure based on the value of unsettled payments. It is lower though than that of the more traditional measures of node activity (value and volume of payments). At this stage, network indicators at the network level seem to be of limited use for stability analysis.

Keywords: Payment systems, operational risk, network topology, stress tests

JEL Classification: E50, G10