Nah. Almost certainly he could lose 100% of that value of the stock without being at risk of anything like this (as in, he probably put up $100m if he wanted a

Nah. Almost certainly he could lose 100% of that value of the stock without being at risk of anything like this (as in, he probably put up $100m if he wanted a $50m loan, etc..) Even if he didn't, the bank would let him move funds in without forcing him to sell.