What types of counterparties can borrow from or lend to a central bank, and what kind of collateral must they possess in order to receive a loan? These are two key aspects of a central bank’s monetary policy implementation framework. Since at least the nineteenth century, it has been understood that an important role of central banks is to lend to solvent but illiquid institutions, particularly during a crisis, as this provides liquidity insurance to the financial system. They also provide liqu