Since mortgages can take up to 30 years to pay off, mortgage lenders typically can’t afford to wait for a full mortgage term to get that money back; they need cash flow to continue to lend new mortgages to home buyers.
To provide that cash flow, investors purchase mortgage notes from lenders. The investor may keep a small number of mortgages in its portfolio, and the rest will be securitized and sold on the bond market.
The largest buyers of conventional mortgages are Fannie Mae and Freddie Mac. These two companies are government-sponsored enterprises. This means that, while they operate independently of the government, they are subject to some supervision that ensures that they’re operating in a responsible way. The government agency that supervises Fannie and Freddie is called the Federal Housing Finance Agency.