New housing finance structures created to increase private capital would leave borrowers with slightly higher interest rates but greatly reduce federal costs, according to a new report from the Congressional Budget Office. The report examined several structures, ranging from a fully federal guarantee on mortgage-backed securities to a largely private market. On a “fair value” basis, it will cost the federal government $19 billion over the next 10 years to backstop an estimated $12 trillion in Fannie Mae and Freddie Mac mortgage-backed securities. The CBO notes the cost “represents the estimated amount that the government would have to pay private guarantors to bear the credit risk of the new guarantees.”