Reproduction steps:
1) Wait for a corporation with a bank branch to be almost bankrupt (typically during depression/recession).
2) As soon as you get the pop-up offer to rescue it from bankruptcy borrow as much money as you can from its bank. Do it with your subsidiaries too for maximum effect.
3) After that acquire the corporation with the bank and DO NOT pay its debts.
4) Once you get the pop up that the acquired corporation has run out of money and that its debts needs to be paid, bankrupt it.
5) Together with the company the bank branch bankrupts and all the money you have borrowed are yours to keep for free. Also, you will get all the remaining deposits liquidated from the bank branch.
6) I have been able to acquire many bankrupting companies/banks like this and made billions super-quickly.