The fund invests at least 80% of its assets in debt securities whose interest is, in the opinion of bond counsel for the issuer at the time of issuance, exempt from federal income tax ("Municipal Bonds"). It may invest in Fixed Income Instruments which include bonds, debt securities and other similar instruments issued by various U.S. and non-U.S. public- or private-sector entities. The fund may invest in derivative instruments, such as options, futures contracts or swap agreements, and invest in mortgage- or asset-backed securities.