
Explanation:
To evaluate how well a VaR model is performing, analysts usually perform backtesting, such as the Kupiec two-tailed test, which looks at the frequency of exceptions (days when the actual loss exceeds the calculated VaR).
For a one-day 95% VaR evaluated over a 250-day period, the expected number of exceptions is 5% of 250, which equals 12.5 exceptions. A statistically sound model should yield exceptions that fall within an acceptable non-rejection confidence interval (typically around 6 to 21 exceptions for a 95% confidence level over 250 days).
Ultimate access to all questions.
Q.14 A large investment firm has a trading book whose size changes depending on the perceived trading opportunities among traders. According to the firm’s chief risk analyst, the one-day VaR, at the 95% confidence level, is GBP 110 million. Suppose you were asked to evaluate how good a job the analyst is doing in estimating the one-day VaR. Assuming that losses are identical and independently distributed, which of the following would serve as convincing evidence that the analyst is performing poorly?
A
Over the past 250 days, there is no exception
B
Over the past 250 days, the mean loss is GBP 132 million
C
Over the past 250 days, the largest loss is GBP 1.1 billion
D
Over the past 250 days, there are seven exceptions
No comments yet.