Strategy. The Funds investment objective is to provide for its shareholders a high level of current income which is exempt from federal regular income tax. The Fund pursues its objective by investing its assets so that normally distributions of annual interest income are exempt from federal regular income tax. The Funds investment adviser (Adviser) may also invest the Funds assets in securities whose interest (while exempt from the federal regular income tax) may be subject to (or may be a specific preference item for purposes of) the federal alternative minimum income tax (AMT) for individuals. The Adviser may lengthen or shorten the duration of the Funds portfolio from time to time based on its interest rate outlook, but the Fund has … Show more… The Funds investment objective is to provide for its shareholders a high level of current income which is exempt from federal regular income tax. The Fund pursues its objective by investing its assets so that normally distributions of annual interest income are exempt from federal regular income tax. The Funds investment adviser (Adviser) may also invest the Funds assets in securities whose interest (while exempt from the federal regular income tax) may be subject to (or may be a specific preference item for purposes of) the federal alternative minimum income tax (AMT) for individuals. The Adviser may lengthen or shorten the duration of the Funds portfolio from time to time based on its interest rate outlook, but the Fund has no set duration parameters. Duration measures the price sensitivity of a fixed-income security to changes in interest rates. The Fund does not limit itself to securities of a particular maturity range. The Fund will invest at least a majority of its assets in securities rated investment grade (or unrated securities of comparable quality), and may purchase securities rated below investment grade (or unrated securities of comparable quality), which are also known as junk bonds, up to 49% of its assets. Investment-grade securities are securities that receive investment-grade ratings (i.e., generally ratings in the first, second, third or fourth highest rating category) by a nationally recognized statistical rating organization (NRSRO) or unrated securities of comparable quality. For example, securities rated AAA, AA, A or BBB (including modifiers, sub-categories or gradations) by S&P Global Ratings, an NRSRO, would be rated in the first, second, third or fourth ratings category, respectively. Securities rated below investment grade (or noninvestment-grade securities) are securities that do not receive investment-grade ratings (i.e., generally ratings below one of the four highest rating categories) by an NRSRO or unrated securities of comparable quality. For example, securities rated B or BB (including modifiers, sub-categories or gradations) by S&P Global Ratings would be noninvestment-grade securities. The presence of a ratings modifier, sub-category, or gradation (for example, a (+) or (-)) is intended to show relative standing within the major rating categories and does not affect the security credit rating for purposes of the Funds investment parameters. The Fund does not have a specific minimum quality rating. The types of securities in which the Fund may principally invest include tax-exempt securities, such as the following types: general obligation bonds, special revenue bonds, private activity bonds, tax increment financing bonds, municipal leases, zero-coupon securities, inverse floaters, municipal mortgage-backed securities, planned amortization classes, variable rate demand instruments, municipal notes and municipal auction rate securities. Certain of the tax-exempt securities in which the Fund invests may be subject to credit enhancement. The Fund also may principally invest in derivative contracts (such as, for example, futures contracts, options contracts and swap contracts) and hybrid instruments to implement its investment strategies. For example, the Fund may use derivative contracts or hybrid instruments in an attempt to benefit from changes in the value of the underlying instrument(s), to gain exposure to the municipal bond sector, to increase or decrease the effective duration of the Funds portfolio or to hedge against potential losses. There can be no assurance that the Funds use of derivative contracts or hybrid instruments will work as intended. Derivative investments made by the Fund are included within the Funds 80% policy (as described below) and are calculated at market value. The Fund also may invest in certain securities or other investments as described herein (such as market discount bonds, credit default swaps and other derivative transactions) that will likely cause the Fund to realize a limited amount of ordinary income or short-term capital gains (which are treated as ordinary income for federal income tax purposes) and, as a result, may result in taxable distributions to shareholders. The Fund will normally invest its assets so that at least 80% of the income that it distributes will be exempt from federal regular income tax. This policy may not be changed without shareholder approval. Show less