@nikic regarding ES, we do not "consider losses beyond the VaR threshold." Averaging losses is called a conditional VaR (or less often, tail conditional expectation, TCE) which has never been assigned and is ambiguous when the VaR is ambiguous. We use expected shortfall (ES) which is never ambiguous and is delimited by the probability not the quantile.
So, for example, if T = 252 trading days and let's say the worst 10 losses were conveniently sorted and given by {-10, -9, -8, -7, -6, -5, -4, ...}, then the 98.0% ES wants the conditional average of the 2.0% tail, so it's neither the average of the worst five or six but rather it is: [1/252*(10 + 9 + 8 + 7 * 6) + ([2% - 5/252]*5)] / 2.0% = 7.976.
@Jaskarn & @nikic are you sure it was 98.0% and T = 252? because that would require a more difficult calculation than simple average of worst 5 or 6? Much easier is 98.0% ES and T= 250 because that is "squarely" the simple average of the worst five ...
Thanks David. In that case I’m not sure most people are even aware of the method you explained to calculate the ES.
I’m 100% positive it was 98% ES for 252 trading days.