Madoff was a fast talking salesman who cared little for his customers and was only interested in making money. Stacking has many similarities to someone with 10 credit cards. FDIC had nothing to do with the mortgage crisis, AIG did when they in effect reinsured the market with their rating when the tranches were monetized. Read "too big to fail". Any deal can fall through at the last minute. They are usually only conditional approvals.