Once upon a time, the US government set up three agencies to provide home loans to people. The Federal National Mortgage Association (FNMA) was founded by FDR to improve the liquidity of the mortgage market. It sits in between the mortgage borrower and the lender. Its job is to assume the risk of mortgage default, in return for a fee. In the 1960s, part of it was removed from the federal balance sheet by spinning it off into a private corporation.