Title
Worst-Case Value at Risk of Nonlinear Portfolios
Abstract
Portfolio optimization problems involving value at risk VaR are often computationally intractable and require complete information about the return distribution of the portfolio constituents, which is rarely available in practice. These difficulties are compounded when the portfolio contains derivatives. We develop two tractable conservative approximations for the VaR of a derivative portfolio by evaluating the worst-case VaR over all return distributions of the derivative underliers with given first-and second-order moments. The derivative returns are modelled as convex piecewise linear or---by using a delta--gamma approximation---as possibly nonconvex quadratic functions of the returns of the derivative underliers. These models lead to new worst-case polyhedral VaR WPVaR and worst-case quadratic VaR WQVaR approximations, respectively. WPVaR serves as a VaR approximation for portfolios containing long positions in European options expiring at the end of the investment horizon, whereas WQVaR is suitable for portfolios containing long and/or short positions in European and/or exotic options expiring beyond the investment horizon. We prove that---unlike VaR that may discourage diversification---WPVaR and WQVaR are in fact coherent risk measures. We also reveal connections to robust portfolio optimization. This paper was accepted by Dimitris Bertsimas, optimization.
Year
DOI
Venue
2013
10.1287/mnsc.1120.1615
Management Science
Keywords
Field
DocType
nonlinear portfolios,risk var,var wqvar approximation,derivative portfolio,portfolio constituent,var approximation,derivative underliers,worst-case value,worst-case var,return distribution,investment horizon,var wpvar,var model,second order,semidefinite programming,robust optimization,exotic option,derivatives,piecewise linear,second order cone programming,value at risk,portfolio optimization
Second-order cone programming,Mathematical optimization,Economics,Exotic option,Robust optimization,Portfolio,Portfolio optimization,Quadratic function,Value at risk,Semidefinite programming
Journal
Volume
Issue
ISSN
59
1
0025-1909
Citations 
PageRank 
References 
18
0.84
14
Authors
3
Name
Order
Citations
PageRank
Steve Zymler11374.70
Daniel Kuhn255932.80
Berç Rustem347936.70