Bethany McLean, writing for Reuters, wrote that taking out Fannie Mae and Freddie Mac from the mortgage business was going to be a challenge. These government-sponsored enterprises guarantee 90% of the mortgages in America. While US President Barack Obama's core idea for housing reform centered on private lending to be the backbone of the housing market, this would be difficult to accomplish given the weight that Fannie and Freddie hold in housing finance.

Of the USD 10 trillion mortgage-related outstanding loans today, the nationalized enterprises of Fannie Mae and Freddie Mac secure USD 4.4 trillion of these debts. US commercial banks, the Federal Reserve, foreign central banks, sovereign wealth funds and mutual funds buy these mortgages from Fannie and Freddie because they don't have to worry about credit risk. These two government sponsored enterprises take care of that.

If the government is completely removed from the mortgage market, investors who back the USD 4 trillion- plus securities of Fannie and Freddie would have to be replaced with "investors who want and can take credit risk, and are willing to invest in a far less liquid instrument." It would be a challenge to find these types of investors as USD 4 trillion is a lot of money.