Value at Risk (VaR) is a statistical technique used to measure and quantify the level of financial risk within a firm or investment portfolio over a specific time frame. This metric is most commonly used by investment and commercial banks to determine the extent and occurrence rate of potential losses in their institutional portfolios. VaR modeling determines the potential for loss in the entity being assessed, and the probability of occurrence for the defined loss. Unlike historical returns, VaR is a forward-looking measure of risk. Historical returns, on the other hand, are purely retrospective and do not provide a timely measurement of risk. Therefore, while VaR measures are appropriate for bank trading portfolios characterized by a short horizon, rapid turnover, and high leverage, historical returns are not. This is because historical returns do not account for the current positions and the potential future losses that could occur in the portfolio.

Choice A is incorrect. The short horizon of trading portfolios necessitates the daily application of VaR measures. This is because the value of these portfolios can change significantly in a short period, and therefore, it's crucial to assess the risk on a daily basis.

Choice B is incorrect. Rapid turnover also requires daily application of VaR measures. Trading portfolios often involve frequent buying and selling of securities, which can lead to significant changes in portfolio value from day to day. Therefore, it's important to measure risk on a daily basis.

Choice D is incorrect. High leverage implies that small changes in asset prices can have large effects on the value of the portfolio due to borrowed funds being used for investment purposes. This makes it necessary for banks' trading portfolios to apply VaR measures daily.

Things to Remember

• Value at Risk (VaR) is a measure of the potential loss in an investment portfolio over a specific time frame.
• VaR is commonly used by banks to assess and manage risk in their trading portfolios.
• VaR is a forward-looking measure of risk, unlike historical returns which are retrospective.