Many different networks can be defined in Financial Systems. Some of them are of such importance that can be considered as examples of social networks. In our group we work along this different lines.

• Board of Directors. That is we consider all the people sitting in the same board and we connect them as an edge.

• Stock Ownership Networks. That is we consider two companies related if one owns stocks of the other

• Stock Correlation Networks. We can draw a Minimal Spanning tree, by connecting the stocks whose returns are more correlated.

• Bank Lending Network. We study the network made of the various transaction made in the Italian bank system.

— GuidoCaldarelli – 09 Nov 2005