FRM Part II · FRM Exam Part II · Beyond Exceedance-Based Backtesting of Value-at-Risk Models
A bank's PIT backtest over 500 days produces a histogram of PIT values that is U-shaped, with excess frequency near 0 and near 1 and too few values near 0.5. What does this most likely indicate about the VaR model's forecast distributions?
A U-shaped PIT histogram means realized outcomes land in the forecast tails too often, so the model's distributions are too narrow and understate risk. An overly wide forecast would instead produce a hump centered near 0.5.
- AThe forecast distributions are too narrow, understating the tails and riskCorrect
- BThe forecast distributions are too wide, overstating risk
- CThe forecasts are unbiased with correct dispersion
- DThe forecasts consistently overestimate profits, causing PIT values to cluster near 0 only
Explanation
Realized outcomes fall in the extreme tails of the forecast distribution more often than expected, so PIT values pile up near 0 and 1. This means the forecast has too little dispersion (underestimates variance). Too-wide forecasts would give a hump-shaped histogram concentrated near 0.5.
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