Interlocking directorates in Italy: persistent links in network dynamics

In this work we study the time evolution of interlocking directorates in Italy from 1998 to 2011 by means of dynamical networks. Our purpose is to assess if in Italy there is a connected and stable structure, due to the presence of directors with multiple mandates, like it happens in the German case. We find a very cohesive network structure, due to the presence of a few directors with multiple assignments and, unlike the German case, this structure is stable, but not connected. Moreover we propose an alternative approach to investigate the dynamics, based on temporal networks, in order to quantify the variation of links in a certain time period. We construct a unique cumulative network, where nodes are companies and the existence of an edge is related with the persistence in time of an interlock between two companies. This persistence is due on the one hand to the ownership of a few family firms, and on the other hand to cross-shareholdings between companies. To complete the analysis we also investigate whether the link stability results from the appointments of the same director or from the stepping in/out of different directors.