FRM Part II · FRM Exam Part II · Parametric Approaches (II): Extreme Value
A risk analyst fits a generalized extreme value (GEV) distribution to the monthly maximum daily losses of a trading portfolio. The estimated tail index ξ is 0.30. Which statement correctly describes the implied behavior of the loss distribution?
A positive tail index of 0.30 indicates the Fréchet type of GEV distribution. Its tail decays as a power law, so it is heavy and unbounded. Gumbel corresponds to a zero tail index and Weibull to a negative one, which would imply thinner or bounded tails.
- AThe tail is thin and bounded, which corresponds to the Weibull type
- BThe tail follows a power law with heavy tails, which corresponds to the Fréchet typeCorrect
- CThe tail declines exponentially, which corresponds to the Gumbel type
- DThe tail is bounded above, so extreme losses cannot exceed a finite maximum
Explanation
In the GEV framework, ξ > 0 corresponds to the Fréchet case, where the tail decays as a power law and is heavy. Financial return losses typically fall into this category. Gumbel arises when ξ = 0 and Weibull when ξ < 0.
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