Problem (Value at Risk) - In finance, VaR does not stand for variance but for "value at risk." It is another measure of risk. It was introduced by J.P. Morgan in the 1980s as a way to answer questions often asked by investors: "How much might I lose?" Let q be a random variable representing the profit on an investment at the end of some time horizon, such as a year. If X is negative, the investment results in a loss. Choose a confidence level, commonly used value is 95%. The 95%-VaR is the value for which P(X < 2) = 0.05. This means that the profit on the investment will be greater than 2 with probability 0.05, and it will be smaller with probability 0.95. In particular, if X is negative and the loss is $1 million or greater, it will occur with probability 0.57.
(1.1) Easy: An investment has a profit at the end of year that is normally distributed with a mean of $1 million and a standard deviation of $0.5 million. What is the 95%-VaR of investment A?
(1.2) Moderate: The investor owning investment A considers the potential loss calculated in (1.1) to be excessive. Risk might be reduced using a hedging strategy. Also available is investment B, with a profit at the end of year that has a mean of $3 million and a standard deviation of $1 million. The correlation between the profits on investments A and B is 0.8. What is the expected profit of investment A+B at the end of year? What is the standard deviation of the profit on investment A+B at the end of year? Assuming that the profit on investment A+B is normally distributed, compute the 95%-VaR of investment A+B.
(1.3) Challenging: The investor is considering hedged portfolios of the form A + B. Can you find the value that minimizes the variance of this portfolio? Assuming that the profit on investment B is normally distributed, compute the 95%-VaR of investment A+B for the value found above.