  This work explores the characteristics of financial contagion in networks
whose links distributions approaches a power law, using a model that defines
banks balance sheets from information of network connectivity. By varying the
parameters for the creation of the network, several interbank networks are
built, in which the concentrations of debts and credits are obtained from links
distributions during the creation networks process. Three main types of
interbank network are analyzed for their resilience to contagion: i)
concentration of debts is greater than concentration of credits, ii)
concentration of credits is greater than concentration of debts and iii)
concentrations of debts and credits are similar. We also tested the effect of a
variation in connectivity in conjunction with variation in concentration of
links. The results suggest that more connected networks with high concentration
of credits (featuring nodes that are large creditors of the system) present
greater resilience to contagion when compared with the others networks
analyzed. Evaluating some topological indices of systemic risk suggested by the
literature we have verified the ability of these indices to explain the impact
on the system caused by the failure of a node. There is a clear positive
correlation between the topological indices and the magnitude of losses in the
case of networks with high concentration of debts. This correlation is smaller
for more resilient networks.
