Short answer is: There used to be a PPT, nowadays there are circuit breakers built into the system that simply just suspends trading after a certain % drop.
If a person wants to understand markets, and in particular the equities market, they can not do better than to read Soros.
'No' simply doesn't cut it as an answer. The government certainly has stepped in & bailed banks out last time, how's that not PPT? Please let's have some fact based info to back your opinion that PPT does not exist. Otherwise, it's nothing more than an opinion of which there are plenty.
%% Anything is possible; as far as vol error, even if 20% or 55% of it is HFT, the remainder is still important.We know the Fed sold silver........................................................
Of course it's a stretch cause people would notice. Central Banks are pretty transparent, even when they try not to be.
And look how that's turned out. All time high was 28 friggen years ago. Or 100% higher than current levels.