Interbank markets and multiplex networks: centrality measures and statistical null models

The interbank market is considered one of the most important channels 6 of contagion. Its network representation, where banks and claims/obligations are 7 represented by nodes and links (respectively), has received a lot of attention in 8 the recent theoretical and empirical literature, for assessing systemic risk and 9 identifying systematically important financial institutions. Different types of links, 10 for example in terms of maturity and collateralization of the claim/obligation, can 11 be established between financial institutions. Therefore a natural representation of 12 the interbank structure which takes into account more features of the market, is 13 a multiplex, where each layer is associated with a type of link. In this paper we 14 review the empirical structure of the multiplex and the theoretical consequences of 15 this representation. We also investigate the betweenness and eigenvector centrality 16 of a bank in the network, comparing its centrality properties across different layers 17 and with Maximum Entropy null models.