The Fund normally invests at least 80% of its total assets in investments the income from which is exempt from U.S. federal income tax (other than AMT). The Fund is an actively managed exchange-traded fund (ETF) that seeks to achieve its investment objective by investing, under normal circumstances, in investment grade municipal debt securities that fund issuers with operations or projects helping to promote progress towards sustainable development, in alignment with the goals and metrics defined by the United Nations Sustainable Development Goals (SDGs) 9, 11 and 12. The SDGs were adopted by the United Nations General Assembly to achieve sustainable development for all, and the specific goals of SDGs 9, 11 and 12 are as follows: SDG 9 is to build resilient infrastructure promote inclusive and sustainable industrialization and foster innovation SDG 11 is to make cities and human settlements inclusive safe resilient and sustainable and SDG 12 is to ensure sustainable consumption and production patterns. The Fund normally invests at least 80% of its total assets in securities that support sustainable development. The Adviser determines which operations or projects of issuers it believes to be supportive of sustainable development and that promote beneficial environmental and social outcomes in U.S. communities and cities by utilizing the rules-based investment approach described below. The Fund's policy to normally invest at least 80% of its total assets in securities that upport sustainable development is non-fundamental and may be changed without shareholder approval upon 60 days' prior written notice to shareholders.