The fact that Robinhood had to emergency-raise $3billion to be able to put up the collateral with their clearing houses should be enough indication that a lot of retail traders were engaged in these highly volatile stocks.
"Clearinghouses are SEC-registered organizations that act as the central depository for securities. They keep a record of the stocks owned through a brokerage. Clearing brokerages, like Robinhood Securities, are members of clearinghouses."
"The amount required by clearinghouses to cover the settlement period of some securities rose tremendously this week. How much? To put it in perspective, this week alone, our clearinghouse-mandated deposit requirements related to equities increased ten-fold."
yes, you just verified robinhood is a clearing broker. they are not a clearinghouse. imagine a clearinghouse as almost guilds brokerages set up to get a useful function they needed that banks do not want to provide. so you have a ton of clearing brokers and they all send their money to the clearinghouse and then they can just forget about everything other than order execution and settlement and ignore all of the hard problems in the middle. the clearinghouse is itself an institution that also has incentives, and one of them is “in periods of extreme volatility, i am going to increase the capital i require to be held here in order to be certain all of the middle bits can be executed”.
i have no idea why people think robinhood is a clearinghouse, that doesn’t make sense. they don’t want to do that! they want to do PFOF with execution or make settlement take 0 days so they can further take advantage of retail or whatever. being a clearinghouse sucks. no one likes you. banks don’t want to do your job.
See e.g. https://fortune.com/2021/02/02/robinhood-gamestop-restricted...