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Checking expected shortfall with a threshold objective

For the original 90% model, threshold 10 gives 10+E[(L−10)+]/0.10=30.

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Use the original loss probabilities

Original same-horizon loss model
Loss unitsProbabilityCumulative probability
−1030%30%
040%70%
1025%95%
505%100%

Compute amounts beyond the chosen threshold

At t=10, losses −10, 0 and 10 have zero positive excess. Loss 50 has excess 40 with probability 5%. Expected excess loss is therefore 0.05×40=2, rather than 0.05×50=2.5.

Compare selected thresholds

Original 90% threshold objective
Threshold tExpected positive excesst + excess / 0.10
0550
10230
50050

Connect to the exact-tail result

The function is convex and piecewise linear in this finite model. Its slope changes where a threshold passes a loss amount; the minimum occurs at 10 for 90% confidence and equals the previously calculated ES 30. The calculator uses direct tail-mass allocation rather than optimizing thresholds.

Check an exact boundary separately

At 95%, the objective is 50 throughout the threshold interval 10 to 50. The threshold minimizer need not be unique even when the ES value is unique.

Further references