Strategy. Under normal circumstances, the High Yield Fund seeks to achieve its objective by investing at least 80% of its assets in municipal bonds. For the purposes of the foregoing 80% policy, assets are the Funds net assets, plus the amount of any borrowings for investment purposes. The Funds investments in derivatives will be counted toward the Funds 80% policy to the extent that they provide investment exposure to the securities included within that policy or to one or more market risk factors associated with such securities. Municipal bonds include debt obligations issued by or on behalf of a governmental entity or other qualifying issuer that pay interest that is, in the opinion of bond counsel to the issuer, generally excludable … Show more… Under normal circumstances, the High Yield Fund seeks to achieve its objective by investing at least 80% of its assets in municipal bonds. For the purposes of the foregoing 80% policy, assets are the Funds net assets, plus the amount of any borrowings for investment purposes. The Funds investments in derivatives will be counted toward the Funds 80% policy to the extent that they provide investment exposure to the securities included within that policy or to one or more market risk factors associated with such securities. Municipal bonds include debt obligations issued by or on behalf of a governmental entity or other qualifying issuer that pay interest that is, in the opinion of bond counsel to the issuer, generally excludable from gross income for Federal income tax purposes (except that the interest may be includable in taxable income for purposes of the Federal alternative minimum tax). Municipal bonds may be obligations of a variety of issuers, including governmental entities or other qualifying issuers. Issuers may be states, territories and possessions of the United States and the District of Columbia and their political subdivisions, agencies and instrumentalities. Municipal bonds also include short-term tax-exempt obligations like municipal notes and variable rate demand obligations. The High Yield Fund may invest in municipal bonds rated in any rating category or in unrated municipal bonds. Although the Fund may invest in municipal bonds in any rating category, Fund management presently intends to invest at least 65% of the Funds net assets in medium- to low-quality bonds as rated by at least one independent rating agency (BBB or lower by S&P Global Ratings (S&P) or Fitch Ratings, Inc. (Fitch) or Baa or lower by Moodys Investors Service, Inc. (Moodys)), or if unrated, judged to be of comparable quality by BlackRock. Obligations rated below BBB or Baa are commonly known as junk bonds. It is possible that the Fund could invest up to 100% of its assets in junk bonds. The Fund may also invest up to 10% of its assets in municipal bonds that are distressed securities. Distressed securities are securities that are the subject of bankruptcy proceedings or otherwise in default as to the repayment of principal and/or payment of interest at the time of acquisition or are rated in the lowest rating categories by at least one independent rating agency (CC or lower by S&P or Fitch or Ca or lower by Moodys), or if unrated, judged to be of comparable quality by BlackRock. The Fund will primarily invest in municipal bonds that have a maturity of five years or longer. Show less