portvrisk (Financial Toolbox)

Portfolio value at risk

Syntax

ValueAtRisk = portvrisk(PortReturn, PortRisk, RiskThreshold, 
PortValue)

Arguments


`PortReturn`	Number of portfolios (`NPORTS`)-by-`1` vector or scalar of the expected return of each portfolio over the period.
`PortRisk`	`NPORTS`-by-`1` vector or scalar of the standard deviation of each portfolio over the period.
`RiskThreshold`	`NPORTS`-by-`1` vector or scalar specifying the loss probability. Default = `0.05` (5%).
`PortValue`	`NPORTS`-by-`1` vector or scalar specifying the total value of asset portfolio. Default = `1`.

Description

ValueAtRisk = portvrisk(PortReturn, PortRisk, RiskThreshold, 
PortValue)

returns the maximum potential loss in the value of a portfolio over one period of time, given the loss probability level RiskThreshold.

ValueAtRisk is an NPORTS-by-1 vector of the estimated maximum loss in the portfolio, predicted with a confidence probability of 1- RiskThreshold.

If PortValue is not given, ValueAtRisk is presented on a per-unit basis. A value of 0 indicates no losses.

Examples

This example computes ValueAtRisk on a per-unit basis.

PortReturn = 0.29/100;
PortRisk = 3.08/100;
RiskThreshold = [0.01;0.05;0.10];
PortValue = 1;
ValueAtRisk = portvrisk(PortReturn,PortRisk,... 
RiskThreshold,PortValue)
ValueAtRisk =

    0.0688
    0.0478
    0.0366

This example computes ValueAtRisk with actual values.

PortReturn = [0.29/100;0.30/100];
PortRisk = [3.08/100;3.15/100];
RiskThreshold = 0.10;
PortValue = [1000000000;500000000];
ValueAtRisk = portvrisk(PortReturn,PortRisk,... 
RiskThreshold,PortValue)
ValueAtRisk =

  1.0e+007 *
    3.6572
    1.8684