The fund invests at least 80% of its net assets in investment-grade quality municipal securities that pay interest that is exempt from regular federal income tax. It may invest up to 20% of its net assets in below investment-grade municipal securities as well as up to 20% of its net assets in securities that produce income subject to federal income tax. The fund may invest up to 20% of its net assets in other investment companies, including closed-end funds and ETFs.