There is surely some deeper non public reason that every single retail broker - but no single institutional broker - stopped accepting GME buys but kept honoring sells. It might or might not be a call from hedge fund buddies, but it is still likely illegal.
When I was working at a hedge fund, I once executed a few hundred mil notional on a supposedly anonymous exchange, taking advantage of an obvious counterparty mistake.
Within 10 minutes, I got a call from said counterparty, telling me that next time I do that, they’ll make sure I’m kicked off the exchange.
Anonymous my ass. Legal my ass. And yet, it happened - I’m sure I wasn’t the first or the last - the other side kept making those mistakes. I stopped taking advantage of them. This kind of behavior is rampant in Wall Street. Only difference is it has been done now in the open, very visibly, and with thousands - perhaps tens of thousands - identifiable victims.
> whether shorting 136% of the stock counts as outright manipulation
I refer you to the snarky top comment about how all the Dunning-Kruger victims who claim manipulation do not actually know what manipulation is. Shorting a stock is not manipulation and neither is lots of people deciding to short a stock. 136% of the stock is shorted because a lot of people were shorting it, not because Some Guy decided to single-handedly short 136% of the float.
> Reddit kids have done nothing but pop an artificial bubble
So GameStop was an artificial bubble at $10 but not at $500? Really?