Most flexible and liquid source of funding for savings banks is

Most flexible and liquid source of funding for savings banks is federal funds market. Federal funds, often referred to as fed funds, are excess reserves that commercial banks and other financial institutions deposit at regional Federal Reserve banks; these funds can be lent, then, to other market participants with insufficient cash on hand to meet their lending and reserve needs. The loans are unsecured and are made at a relatively low interest rate, called the federal funds rate or overnight rate, as that is the period for which most such loans are made.