Citigroup (NYSE:C) is one of the world's largest diversified financial services firms, which means that it makes money by loaning out money and receiving interest on the loans. Citi had significant exposure to the subprime mortgage industry and suffered considerable losses in 2007 and 2008 from large write-downs and write-offs on many of its mortgage-backed securities and collateralized debt obligations. Citi posted a loss of $6,733 million in 2009, a 66.6% decrease from a loss of $20,326 million in 2008.[1]