The federal government is trying to get taxpayers off the hook for billions of dollars of potential losses if another mortgage crisis arrives, and in the process, it is quietly giving birth to a new asset class, The Wall Street Journal reported. Under government control, mortgage-finance giants Fannie Mae and Freddie Mac next year plan to ramp up sales of new types of securities that in effect transfer potential losses in a housing downturn to private investors. Called Connecticut Avenue Securities by Fannie Mae and Structured Agency Credit Risk by Freddie Mac, the securities are essentially bonds whose performance is tied to that of a pool of mortgages. If the mortgages default, investors in the bonds could lose some or all of their principal.