The Federal National Mortgage Association (Fannie Mae) was originated during the Great Depression as a part of the New Deal. The purpose of the Association is to insure or securitize mortgages made by lenders in the form of mortgage backed securities. This relationship with your lender allows them to re-invest their money or assets into other loans. This is a great benefit to the American people as it frees up the bank to lend to more people, creating more borrowers, and ultimately more wealth for our society.
Most of the loans today that are undertaken by banks are sold to or insured by Fannie Mae or the smaller Freddie Mac. In many ways this is good, as the Fannie Mae and Freddie Mac requirements are keeping the banks honest with their guidelines, only buying the safer loans. One negative, which is a big negative, is we are putting a lot of faith in Fannie Mae and Freddie Mac, some would say too much.