I don't really understand why they would need to put up a margin in order to execute/clear a fully paid buy order on the exchange. Users promised $x in exchange for stock. RH have their $x. RH needs to make good on the exchange or clearing house. Seems to me that risk runs the other way... Other brokers/clearing house participants might be unable to pay RH users because leverage + a unexpectedly high stock price.
I understand why RH would shut down leverage. After that point, I don't understand why/how stock purchases represent a risk to anyone but the buyer. How is the non-leveraged side creating a risk of nonpayment? I really don't know how any of this works though, so let's leave this all aside. Lets grant that RH/users are at risk of being unable to cover trades.
So what? GME buys on RH create a scenario that risks RH running out of money. So what? Why/how does this risk the clearing houses? It's a $20bn stock. A 2% move in any of the big companies is a $20bn.
I understand why RH would shut down leverage. After that point, I don't understand why/how stock purchases represent a risk to anyone but the buyer. How is the non-leveraged side creating a risk of nonpayment? I really don't know how any of this works though, so let's leave this all aside. Lets grant that RH/users are at risk of being unable to cover trades.
So what? GME buys on RH create a scenario that risks RH running out of money. So what? Why/how does this risk the clearing houses? It's a $20bn stock. A 2% move in any of the big companies is a $20bn.