Average -1.2 stdev = -0.651 Average +1.2 stdev = 5.8751
Current -5.3
So my average of 2.61 is a bit higher than your 1.88 average.
Similarly my 80% boundaries (1.28 stdev) shows top 10% of around 5.87% vs your 3.8 and my lower 10% of -0.65 vs your -0.85
Whilst different the two seem reasonably close generally. And the current -5.3 (your -3.17) certainly is very deeply into the bottom 10%. At over 3 standard deviations down from the average it's in excess of 99.7%
A Black Swan (6 sigma) event would require a 12.6% I-MD value.