Cash in a bank isn't "locked up." The bank uses it to make loans. In a sense, it expands the supply of money because a bank isn't required to have 100% cash res

Cash in a bank isn't "locked up." The bank uses it to make loans. In a sense, it expands the supply of money because a bank isn't required to have 100% cash reserves. So $50 billion in bank accounts generates more than $50 billion in loans.