On the price of risk in a mean-risk optimization model

Darinka Dentcheva, Gregory J. Stock

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

We investigate a mean-risk model for portfolio optimization where the risk quantifier is selected as a semi-deviation or as a standard deviation of the portfolio return. We analyse the existence of solutions to the problem under general assumptions. When the short positions are not constrained, we establish a lower bound on the cost of risk associated with optimizing the mean–standard deviation model and show that optimal solutions do not exist for any positive price of risk which is smaller than that bound. If the investment allocations are constrained, then we obtain a lower bound on the price of risk in terms of the shadow prices of said constraints and the data of the problem. A Value-at-Risk constraint in the model implies an upper bound on the price of risk for all feasible portfolios. Furthermore, we provide conditions under which using this upper bound as the cost of risk parameter in the model provides a non-dominated optimal portfolio with respect to the second-order stochastic dominance. Additionally, we study the relationship between minimizing the mean–standard deviation objective and maximizing the coefficient of variation and show that both problems are equivalent when the upper bound is used as the cost of risk. Additional relations between the Value-at-Risk constraint and the coefficient of variation are discussed as well. We illustrate the results numerically.

Original languageEnglish
Pages (from-to)1699-1713
Number of pages15
JournalQuantitative Finance
Volume18
Issue number10
DOIs
StatePublished - 3 Oct 2018

Keywords

  • Coefficient of variation
  • Mean-semi-deviation
  • Portfolio optimization
  • Stochastic orders
  • Value-at-risk

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