I am talking about a situation where first a contract is signed where the whole bank is being sold including the stash of coins in their possession. A month later the actual change of ownership of the whole bank happens when new owner gets his personnel to take over. During that month the previous owner still has complete control of the bank but he has nothing to lose if the coins in the banks possession collapse in value. He still can transfer the 100 million coins to the new owner of the bank a month later like it says on the contract and he could not care less whether the coins have value or not.

Note that there does not have to be an actual attack. All that is needed is market to know that a big bank is changing ownership and the whole market knows that the stability of the whole economy is hanging by a thread during this month. Maybe somebody else sees this as an perfect opportunity to perform an actual attack and they also do not need to be nothing else than big nasty rumours that cause panic.