VaR is not a Bad Risk Measure

VaR has taken a lot of heat in the current financial crisis. Some go so far as to blame the financial crisis on VaR.

But VaR is a good risk measure. The problem is with the word RISK. You see, VaR has a precise definition, RISK does not. There is no way that you could possible measure an ill defined idea as RISK with a precise measure.

VaR is a good measure of one aspect of RISK. Is measures volatility of value under the assumption that the future will be like the recent past. If everyone understands that is what VaR does, then there is no problem.

Unfortunately, some people thought that VaR measured RISK period. What I mean is that they were led to believe that VaR was the same as RISK. In that context VaR (and any other single metric) is a failure. VaR is not the same as RISK.

That is because RISK has many aspects. Here is one partial list of the aspects of risk:

Type A Risk – Short Term Volatility of cash flows in 1 year
Type B Risk – Short Term Tail Risk of cash flows in 1 year
Type C Risk – Uncertainty Risk (also known as parameter risk)
Type D Risk – Inexperience Risk relative to full multiple market cycles
Type E Risk – Correlation to a top 10
Type F Risk – Market value volatility in 1 year
Type G Risk – Execution Risk regarding difficulty of controlling operational losses
Type H Risk – Long Term Volatility of cash flows over 5 or more years
Type J Risk – Long Term Tail Risk of cash flows over 5 years or more
Type K Risk – Pricing Risk (cycle risk)
Type L Risk – Market Liquidity Risk
Type M Risk – Instability Risk regarding the degree that the risk parameters are stable
(excerpted from Risk & Light)

VaR measures Type F risk only.

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Explore posts in the same categories: Correlation, Execution Risk, Risk, Risk and Light, Risk Management, Tail Risk, Value at Risk, VaR, Volatility

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