The precipitating factor was a high default rate in the subprime home mortgage sector. The expansion of this sector had been encouraged by the Community Reinvestment Act (CRA), a US federal law first passed in 1977 and subsequently revised, which was designed to help poorer American inner-city dwellers get mortgage loans. Many of these subprime (high risk) loans were then bundled and sold, finally accruing to quasi-government agencies (Fannie Mae and Freddie Mac)