Fannie Mae is a government sponsored enterprise (GSE) of the United States federal government. It is a shareholder-owned corporation authorized to make loans and loan guarantees. It is the leading market-maker in the U.S. secondary mortgage market, which helps to replenish the supply money for mortgages and enables money to be available for housing purchases. As of 2008, Fannie Mae and Freddie Mac (the Federal Home Loan Mortgage Corporation) own or guarantee about half of the U.S.'s $12 trillion mortgage market. As a result, the corporations were affected particularly hard by the subprime mortgage crisis in late 2007 and early 2008.