MainStay DefinedTerm Municipal Opportunities Fund (the Fund), formerly MainStay DefinedTerm Municipal High Income Fund, is a diversified, closed-end management investment company. The Fund's primary investment objective is to seek current income exempt from regular the United States Federal income taxes. The Fund's secondary objective is total return. The Fund seeks to achieve its investment objectives by investing, under normal market conditions, at least 80% of its Managed Assets in municipal bonds, the interest on which is, in the opinion of bond counsel to the issuers, generally excludable from gross income for regular the United States Federal income tax purposes. The Fund may invest in other registered investment companies, including open- and closed-end funds and exchange-traded funds (ETFs). New York Life Investment Management LLC (New York Life Investments) will administer the Fund's business affairs and manage the investment operations of the Fund.