But it was all retail brokers who imposed restrictions for 4 days
Yes. Because their CLEARING FIRMS WOULD NOT ACCEPT THEIR RISK. WHAT is so hard to understand about this? You think Apex should have agreed to be disciplined and fined by FINRA for letting Robinhood screw up??
Robinhood's 3+ billion probably barely covered its requirements. And now it'll have to deal with the consequences of the loans it took. If I were a Robinhood client, I'd be wondering whether the firm will survive.