[u678u]

I was wondering about this too then I thought about people trading out of regular stocks and buying GME/AMC. When you sell a stock today you get the cash two days later, but your broker will let you buy today and normally they will settle together. It sounds like the clearing houses were demanding 100% today for any GME buys. So if you had customers selling $1 billion of regular stocks and buying GME the brokerage would have to come up with $1bil today or get closed down. I'm guessing they're scared of that happening.