"Fannie Mae" is a colloquial expression derived from "FNMA", itself standing for the Federal National Mortgage Association. Fannie Mae, created in 1938, is a government-sponsored enterprise that expands the rate of mortgages by creating a secondary mortgage market. Fannie Mae therefore purchases and guarantees mortgages that meet basic funding criteria. Fannie Mae then packages mortgages into mortgage-backed securities, creating an extremely large and fluid market. Fannie Mae purchases somewhere in the neighborhood of one-half of all US mortgages, depending on market conditions. It is a publicly-traded company operating through a congressional charter directing Fannie Mae to increase the availability of mortgages for low-, moderate-, and middle-class Americans.