IB claimed to have hiked margin to 100% which is a reasonable response. However, I have heard from many sources that they in fact rejected buy orders even with

IB claimed to have hiked margin to 100% which is a reasonable response. However, I have heard from many sources that they in fact rejected buy orders even with cash - which, if true, and I have every reason to believe so, makes any explanation about margins and technical reasons seem ridiculous. 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.