We consider the optimal portfolio selection problem subject to a maximum value-at-Risk (MVaR) constraint when the price dynamics of the risky asset are governed by a Markov-modulated geometric Brownian motion (GBM). Here, the market parameters including the market interest rate of a bank account, th
Optimal portfolios under a value-at-risk constraint
β Scribed by K.F.C. Yiu
- Publisher
- Elsevier Science
- Year
- 2004
- Tongue
- English
- Weight
- 568 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0165-1889
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β¦ Synopsis
This paper looks at the optimal portfolio problem when a value-at-risk constraint is imposed. This provides a way to control risks in the optimal portfolio and to fulΓΏl the requirement of regulators on market risks. The value-at-risk constraint is derived for n risky assets plus a risk-free asset and is imposed continuously over time. The problem is formulated as a constrained utility maximization problem over a period of time. The dynamic programming technique is applied to derive the Hamilton-Jacobi-Bellman equation and the method of Lagrange multiplier is used to tackle the constraint. A numerical method is proposed to solve the HJB-equation and hence the optimal constrained portfolio allocation. Under this formulation, we ΓΏnd that investments in risky assets are optimally reduced by the imposed value-at-risk constraint.
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