The fund invests at least 80% of its assets in Government National Mortgage Association (GNMA) pass-through certificates, which are fixed income securities representing part ownership in a pool of mortgage loans supported by the full faith and credit of the U.S. government. It may invest in other types of securities such as U.S. Treasury or other U.S. government agency securities. The fund's dollar-weighted average maturity will normally fall within an intermediate-term range (3 to 10 years).