This paper sets forth a new perspective to address some problems that arise from the mixed governance nature of a state-owned bank. Firstly, it stresses that the principle of subsidiarity is at the root of decision-making processes in which the bank involves itself on the grounds of political demands. Secondly, it focuses on the uses and misuses of the principle of subsidiarity, putting forward the notion of the subsidiarity portfolio to redress misuses and enhance the governance of these institutions. Next, it defines the assets and liabilities portfolios of the bank and, by means of a break-even analysis of those portfolios'returns, inclusive of the costs-benefit structure, it introduces the rate of subsidiarity. Afterwards it moves on to the negative spread to measure up how far the subsidiarity abuse acts upon the return and costs-benefit structure of the bank. Lastly, it enlarges about likages between risk and subsidiarity on the one hand, and quasi-fiscal activities on the other hand.