Assuming Robinhood's story was accurate that everyone was trading on margin (at least by default and thus a lot of traders) and that they were approaching some serious questions about if they had enough cash on had to cover the trades / possible losses ... I'm not sure what the right thing to do in that case would be.
Keep everyone trading and possibly run out of cash to cover everything? Or stop trading and possibly hose the folks trying to make trades?
Keep everyone trading and possibly run out of cash to cover everything? Or stop trading and possibly hose the folks trying to make trades?