Why anyone would pay $30 per share for a fund whose portfolio value per share is only $10 is not well understood, although irrational exuberance has been mentioned.
Portfolio insurance is an investment strategy where various financial instruments like equities and debts and derivatives are combined in such a way that degradation of portfolio value is protected.
Value at risk is, however, coherent, under the assumption of elliptically distributed losses (e.g. normally distributed) when the portfolio value is a linear function of the asset prices.
