The article explores how rules about how much money banks must keep on hand can help control the risks they take. Banks often choose riskier investments because they know they are protected by insurance. The study found that simple rules about how much money banks must keep are not very effective at reducing the risk of banks going bankrupt. Instead, the study suggests using more complex rules that take into account the specific risks of each investment. By doing this, banks can be encouraged to make safer investment choices, which can help prevent financial crises.