Optimal capital allocation principles considering capital shortfall and surplus risks in a hierarchical corporate structure

Abstract

When allocating a given total capital among main business lines and their sub-business lines, a decision maker will face both capital shortfall risk and capital surplus risk for each business line. There is a trade-off between the two kinds of risks. To balance such two kinds of risks in main business lines and their sub-business lines, we propose a capital allocation model considering both capital shortfall risks and capital surplus risks in a hierarchical corporate structure. We derive optimal allocation principles as solutions that minimize a general loss function that balances the shortfall and surplus risks. As applications of the proposed model, a general proportional allocation principle in the presence of a hierarchical corporate structure is derived. It is illustrated that the general proportional allocation can be viewed as the unique solution minimizing a specified loss function in the proposed model. Connections between this proposed model and some risk factors, such as dependence, extreme events, exogenous risks, and risk measures, are discussed.