The greatest risk we face, therefore, is that of the mis-specification of financial price dynamics by the available models. The two-standard-deviations (and higher) VAR is very sensitive to model specification. The sensitivity is compounded with every additional increase in dimension (that is, in the number of securities included). For portfolios of 75 securities (a small portfolio for a trading room), I have seen frequent seven- and higher standard-deviation variations during quiet markets. Thus VAR is not adapted for the brand of diversified leverage we usually take in trading firms. I call this the risk of incompleteness, or the model risk. A model might show you some risks, but not the risks of using it. Moreover, models are built on a finite set of parameters, while reality affords us infinite sources of risks.