A government-sponsored enterprise (GSE) is a type of financial services corporation created by the United States Congress. Their intended function is to enhance the flow of credit to targeted sectors of the economy, to make those segments of the capital market more efficient and transparent, and to reduce the risk to investors and other suppliers of capital. The desired effect of the GSEs is to enhance the availability and reduce the cost of credit to the targeted borrowing sectors primarily by reducing the risk of capital losses to investors: agriculture, home finance and education. Well known GSEs are the Federal National Mortgage Association, known as Fannie Mae, and the Federal Home Loan Mortgage Corporation, or Freddie Mac. Congress created the first GSE in 1916 with the creation of the Farm Credit System. It initiated GSEs in the home finance segment of the economy with the creation of the Federal Home Loan Banks in 1932; and it targeted education when it chartered Sallie Mae in 1972 (although Congress allowed Sallie Mae to relinquish its government sponsorship and become a fully private institution via legislation in 1995). The residential mortgage borrowing segment is by far the largest of the borrowing segments in which the GSEs operate. GSEs hold or pool approximately $5 trillion worth of mortgages. Backing of US currency The U.S. Congress has specified that Federal Reserve Banks must hold collateral equal in value to the Federal Reserve notes that the Federal Reserve Bank puts into circulation. This collateral is chiefly held in the form of U.S. Treasury, federal agency, and government-sponsored enterprise securities. Business Congress established GSEs to improve the efficiency of capital markets and to overcome market imperfections which prevent funds from moving easily from suppliers of funds to areas of high loan demand. This is primarily done by some form of guarantee that limits the risk of capital losses to those supplying funds. Presently, GSEs primarily act as financial intermediaries to assist lenders and borrowers in housing and agriculture. Fannie Mae and Freddie Mac, the two most prominent GSEs, purchase mortgages and package them into mortgage-backed securities (MBS), which carry the financial backing of Fannie Mae or Freddie Mac. Because of this GSE financial backing, these MBS are particularly attractive to investors and are also eligible to trade in the "to-be-announced," or "TBA" market. In addition, the GSEs created a secondary market in loans through guarantees, bonding and