I think the wording in the FDIC order was that customers were "initiating 42bn of withdrawals."[0] Doesn't mean those went through (in fact many from what I heard didn't.)
Still certainly very possible that the analysis is incorrect.
"The yield they wanted to see on this capital" I imagine is some combination of money needed to run operations of the bank, interest paid on the deposits and profit.
They could have just stored the money in the proverbial vault. But if they do that, then they have to charge the depositors a fee to be a customer. And competition has pushed in the other direction.
And probably more importantly that whole "profit" goal.
I thought the follwoing was an interesting analysis: Aside from the fact that those assets don't seem to be valued at the current price (i.e. are marked at cost basis, not market,) much of it is already pledged as collateral.