Mean-risk model for portfolio selection with uncertain returns

This paper discusses the uncertain portfolio selection problem when security returns are hard to be well reflected by historical data. In portfolio selection, risk analysis is one of the most important topics and research on quantitative definition of risk remains core of the topic. A new risk measure is introduced in this paper. Based on the new risk function, a mean risk model is proposed. In addition, the gravitation search algorithm is introduced to solve the proposed model. Finally, a numerical example is given to illustrate the modelling idea and the availability of the algorithm.