  The question we address here is of whether phenomena of collective
bankruptcies are related to self-organized criticality. In order to answer it
we propose a simple model of banking networks based on the random directed
percolation. We study effects of one bank failure on the nucleation of
contagion phase in a financial market. We recognize the power law distribution
of contagion sizes in 3d- and 4d-networks as an indicator of SOC behavior. The
SOC dynamics was not detected in 2d-lattices. The difference between 2d- and
3d- or 4d-systems is explained due to the percolation theory.
