Strategy. Under normal circumstances, the Fund seeks to achieve its objective by investing at least 80% of its net assets, plus any borrowings for investment purposes, in municipal bonds and derivatives with similar economic characteristics. 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 … Show more… Under normal circumstances, the Fund seeks to achieve its objective by investing at least 80% of its net assets, plus any borrowings for investment purposes, in municipal bonds and derivatives with similar economic characteristics. 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 Fund will seek to invest in municipal bonds that BlackRock believes have the potential to produce attractive Federal tax-free income and the proceeds of which, in BlackRocks view, can provide positive and measurable impacts. BlackRock considers a number of criteria when selecting portfolio securities, including, but not limited to, whether the activities supported by the investment are expected to include positive social externalities, responsible use of proceeds, measurable and clear impacts, benefit to undercapitalized or high social opportunity areas, and alignment with broadly endorsed public policy goals. The Funds investments will be focused across themes that align with certain United Nations Sustainable Development Goals (SDGs), including, but not limited to, good health and well-being; quality education; clean water and sanitation; affordable and clean energy; industry, innovation, and infrastructure; and sustainable cities and communities. The SDGs are a series of goals published by the United Nations that recognize that ending poverty and other deprivations must go hand-in-hand with improvements in health, education, and economic growth, and reduction in inequalities, while tackling climate change and working to preserve the planets oceans and forests. The Fund intends to focus its investments in municipal bond issuers within certain sectors, including but not limited to the education, healthcare, housing, water and sewer, low-carbon public power issuers, mass transit, and state and local governments sectors. Within these sectors, Fund management applies BlackRocks proprietary municipal impact framework to seek to invest in bonds whose proceeds, in BlackRocks view, generate positive, measurable social and/or environmental impacts. BlackRocks proprietary framework abides by the Operating Principles for Impact Management, which is a third-party framework for investors for the design and implementation of their impact management systems to ensure that impact considerations are integrated throughout the investment lifecycle. Fund management looks to key performance indicators to measure the impact of the Funds investments, and the nature of such assessments may vary by sector and over time. For example, within the education sector, Fund management may seek opportunity for impact through projects that aim to improve educational attainment and learning outcomes, innovations in technology to help close learning gaps, providing alternative learning methods and expanded early childhood programs for underserved populations. Within the healthcare sector, Fund management may seek investments that fund projects that work to achieve health equity, provide access to quality healthcare and improved outcomes, reduce the cost of healthcare, increase the capacity of, and improve the resiliency of, healthcare infrastructure. The foregoing examples are for illustration only, and the nature of the impact outcomes sought in a particular sector may vary. The impact-related criteria described above are not the sole considerations when making investment decisions for the Fund, and the Fund will make investments that do not meet the impact-related criteria. In addition, the Fund may gain indirect exposure (through, including but not limited to, derivatives and investments in other investment companies) to issuers with exposures that are inconsistent with the impact-related criteria used by Fund management. The Fund may invest in municipal bonds rated in any rating category or in unrated municipal bonds. The Fund may invest up to 50% of its assets in junk bonds or in unrated bonds that Fund management believes are of comparable quality. The Fund will primarily invest in municipal bonds that have a maturity of five years or longer. The Fund may also invest up to 10% of its assets in taxable securities under normal market conditions. The Fund may engage in transactions in certain derivatives, such as financial futures contracts and options thereon, indexed and inverse floating rate obligations and swap agreements, including credit default swap agreements. The Fund may use derivative instruments to hedge its investments or to seek to enhance returns. The Fund may leverage up to 10% of its assets through the use of proceeds received through tender option bond transactions. In a tender option bond transaction, the Fund transfers municipal bonds or other municipal securities into a special purpose entity (a TOB Trust). A TOB Trust typically issues two classes of beneficial interests: short-term floating rate interests (TOB Floaters), which are sold to third party investors, and residual inverse floating rate interests (TOB Residuals), which are generally issued to the Fund. The Fund may invest in TOB Residuals and may also invest in TOB Floaters. The Fund will look through to the underlying municipal bond held by a TOB Trust for purposes of the Funds 80% policy. The Fund may also invest in variable and floating rate instruments, and transact in securities on a when-issued, delayed delivery or forward commitment basis. Show less