This paper by Douglas W. Diamond and Philip H. Dybvig analyzes the role of banks in providing liquidity and the mechanisms that prevent bank runs. It shows that bank deposit contracts can offer better risk sharing than exchange markets, allowing banks to attract deposits despite the risk of runs. Bank runs occur due to multiple equilibria, one of which is a panic-driven withdrawal. The paper argues that bank runs cause real economic damage, not just reflecting other problems. It examines contracts that can prevent runs and shows that government deposit insurance can provide superior contracts in certain circumstances. The model demonstrates that banks can improve risk sharing by transforming illiquid assets into liquid liabilities. However, this creates multiple equilibria, one of which is a bank run. Bank runs are costly and reduce social welfare by disrupting production and destroying optimal risk sharing. The paper also shows that deposit insurance can prevent runs without reducing the ability of banks to transform assets. It argues that deposit insurance is a natural provider of insurance due to the government's taxation authority, although there may be a competitive fringe of private insurance. The paper also discusses the role of the Federal Reserve discount window as a lender of last resort, which can provide services similar to deposit insurance. However, if the technology is risky, the lender of last resort may not be as credible as deposit insurance. The paper concludes that deposit insurance is a binding commitment that can punish bank owners, directors, and officers in the case of failure. It also suggests that the potential for multiple equilibria applies more generally, not just to banks. The paper highlights the importance of financial intermediaries in managing liquidity risk and suggests that most of the aggregate liquidity risk in the U.S. economy is channeled through insured financial intermediaries. The paper concludes that deposit insurance is a key policy tool for preventing bank runs and ensuring the stability of the financial system.This paper by Douglas W. Diamond and Philip H. Dybvig analyzes the role of banks in providing liquidity and the mechanisms that prevent bank runs. It shows that bank deposit contracts can offer better risk sharing than exchange markets, allowing banks to attract deposits despite the risk of runs. Bank runs occur due to multiple equilibria, one of which is a panic-driven withdrawal. The paper argues that bank runs cause real economic damage, not just reflecting other problems. It examines contracts that can prevent runs and shows that government deposit insurance can provide superior contracts in certain circumstances. The model demonstrates that banks can improve risk sharing by transforming illiquid assets into liquid liabilities. However, this creates multiple equilibria, one of which is a bank run. Bank runs are costly and reduce social welfare by disrupting production and destroying optimal risk sharing. The paper also shows that deposit insurance can prevent runs without reducing the ability of banks to transform assets. It argues that deposit insurance is a natural provider of insurance due to the government's taxation authority, although there may be a competitive fringe of private insurance. The paper also discusses the role of the Federal Reserve discount window as a lender of last resort, which can provide services similar to deposit insurance. However, if the technology is risky, the lender of last resort may not be as credible as deposit insurance. The paper concludes that deposit insurance is a binding commitment that can punish bank owners, directors, and officers in the case of failure. It also suggests that the potential for multiple equilibria applies more generally, not just to banks. The paper highlights the importance of financial intermediaries in managing liquidity risk and suggests that most of the aggregate liquidity risk in the U.S. economy is channeled through insured financial intermediaries. The paper concludes that deposit insurance is a key policy tool for preventing bank runs and ensuring the stability of the financial system.