Minimal Investment Risk of Portfolio Optimization Problem with Budget   and Investment Concentration Constraints
  In the present paper, the minimal investment risk for a portfolio optimization problem with imposed budget and investment concentration constraints is considered using replica analysis. Since the minimal investment risk is influenced by the investment concentration constraint (as well as the budget constraint), it is intuitive that the minimal investment risk for the problem with an investment concentration constraint be larger than that without the constraint (that is, with only the budget constraint). Moreover, a numerical experiment shows the effectiveness of our proposed analysis. 
Takashi Shinzato
q-fin.PM cond-mat.dis-nn math-ph math.MP