The First Trust Flexible Municipal High Income ETF (the "Fund") (formerly First Trust Municipal CEF Income Opportunity ETF) seeks to provide current income. Under normal market conditions, the Fund seeks to achieve its investment objective by investing at least 80% of its net assets (plus any investment borrowings) in municipal debt securities that pay interest that is exempt from regular federal income taxes. Municipal debt securities are generally issued by or on behalf of states, territories or possessions of the United States and the District of Columbia and their political subdivisions, agencies, authorities and other instrumentalities. The Fund may invest in a range of municipal securities, including, but not limited to, municipal lease obligations (and certificates of participation in such obligations),municipal general obligation bonds, municipal revenue bonds, municipal notes, municipal cash equivalents, private activity bonds (including without limitation industrial development bonds), and pre-refunded and escrowed to maturity bonds.