The fund normally invests at least 80% of its net assets in U.S. government securities. It invests substantially all of its assets in Government National Mortgage Association obligations (Ginnie Maes). The mortgage loans may have either fixed or adjustable interest rates. As the underlying mortgage loans are paid off, Ginnie Maes provide investors with monthly payments of interest and principal as well as any unscheduled prepayments on the underlying mortgage loans.