The article discusses a new way to evaluate the stability of banking systems by looking at how banks' assets are connected. They found that the main risk to the system comes from banks having similar investments, rather than one bank failing and causing others to fail. Even though bank failures spreading to others are rare, they can have a big impact. To prevent this, it's important to have low costs for dealing with bankruptcies and a good plan for handling crises. Surprisingly, it wouldn't take much money for a lender of last resort to stop a chain reaction of bank failures.