Here’s the part that makes no sense to me: why can’t Robinhood use customer funds for their deposit? Imagine a degenerate case: all but one client make no trades at all. One client has $100k deposited and buys $100k worth of GME. Prior to settlement, GME drops by 50%. That client is (effectively) out the entire $100k, and they are owed $50k worth of GME. Robinhood needs to post somewhere between $50k and $100k of collateral to the clearinghouse.

This all seems entirely reasonable with one giant of exception: apparently Robinhood may not draw on the client’s deposit for this. Never mind that, at settlement, the client will be debited the entire $100k. Somehow Robinhood is expected to temporarily come up with an additional $50k-$100k for a two day period. This seems bizarre to me.