  Interbank deposits (loans and credits) are quite common in banking system all
over the world. Such interbank co-operation is profitable for banks but it can
also lead to collective financial failures. In this paper we introduce a new
model of directed percolation as a simple representation for contagion process
and mass bankruptcies in banking systems. Directed connections that are
randomly distributed between junctions of bank lattice simulate flows of money
in our model. Critical values of a mean density of interbank connections as
well as static and dynamic scaling laws for the statistic of avalange
bankruptcies are found. Results of computer simulations for the universal
profile of bankruptcies spreading are in a qualitative agreement with the third
wave of bank suspensions during The Great Depression in the USA.
