Regulators wanted to see if banks with enough money were less likely to fail. They looked at 560 US banks from 2003 to 2009. Banks with less than 6% of the right kind of money were more likely to fail. During the financial crisis, this only mattered if banks had at least 8% of the right kind of money. But, a different measure was even better at predicting bank failure than having enough money. This is important for deciding how much money banks should have during tough times.