Because there were no offenders. DTCC raising collateral requirements on an ultravoltile stock with a high chance of price collapse is just... a reasonable thing to do?
Do they have a prepublished volatility-collateral chart that applies for this and all similar scenarios or was this an adhoc rule change made arbitrarily this one time? Can you show another volatile time where similar action was taken?
Can you point to a GME like price action of a non-penny stock ticker? Of course we both know the answer is no. Things shot up, things shot down, of course people who bought the hype lost money. There is nothing surprising here.
Evidently you don't know what you're talking about - of course I can. $VW 2008, $ACB 2019, $TLRY 2018 to name a few. There is much more, simply go through tickers on D1 chart and you'll see.
Evidently you don’t understand difference in the size of this run up?
VW, the mother of short squeezes driven on unexpected Porsche purchase went from $200 to $1000, eg 5x
$ACB had no short squeeze, they had some run ups, with biggest in 2018 of $66 to $194
$TLRY peaked at $300 with historic low of $21 and it took months.
$GME went from $4.2 to $482 in about 5 months, none of the previous tickets you mentioned moved literally >100x. Even in 2021 GME went from $17, so over 25x in one month, this has no precedent. It leaves VW and TLRY entirely in the dust, they are not even close.
Then why disable buying and not selling, if things were volatile the exchange could have stepped in and stop the trading. There was really no reason for DTCC to increase the margin to 100%.
They disabled buying because they need to put up collateral on buys, not on sells (on sells you just pledge the shares you hold). They increased collateral because if a bunch of people buy and go bust by the time settlement time hits (because of GME price collapse) then dtcc would be on a huge hook.