MainStay MacKay DefinedTerm Municipal Opportunities Fund (MMD) N-CSRS Certified semi-annual shareholder report (management investment company)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT

INVESTMENT COMPANIES

Investment Company Act File Number 811-22551

MAINSTAY DEFINEDTERM

MUNICIPAL OPPORTUNITIES FUND

(Exact name of Registrant as specified in charter)

51 Madison Avenue, New York, NY 10010

(Address of principal executive offices) (Zip code)

J. Kevin Gao, Esq.

30 Hudson Street

Jersey City, New Jersey 07302

(Name and address of agent for service)

Registrant’s telephone number, including area code: (212) 576-7000

Date of fiscal year end: May 31

Date of reporting period: November 30, 2017

FORM N-CSR

Item 1. Reports to Stockholders.

MainStay DefinedTerm Municipal Opportunities Fund

Message from the President and Semiannual Report

Unaudited  |  November 30, 2017  |  NYSE Symbol MMD

This page intentionally left blank

Message from the President

The six months ended November 30, 2017, brought strong performance to equity markets in the United States and abroad.

According to FTSE-Russell data for the U.S. market, stocks at all capitalization levels earned solid double-digit overall returns during the reporting period, and growth stocks were particularly strong. These results reflected raised hopes that the new U.S. administration might provide business tax incentives and possible tax cuts for consumers that could stimulate economic growth.

Developed international markets and emerging markets provided strong positive total returns during the reporting period, boosted by positive macroeconomic data and growing confidence that Europe was well on its way to financial recovery. Despite wide variations among emerging markets, many saw solid appreciation in local-currency terms and benefited from a weaker U.S. dollar.

During the reporting period, the Federal Open Market Committee raised the federal funds target range in June of 2017. This incremental increase raised the federal funds target range to 1.00% to 1.25% by the end of the reporting period. The tightening move was followed by higher yields for U.S. Treasury securities at all maturities except 30-year bonds, whose yields slightly declined.

As interest rates rise, bond prices tend to decline (and vice versa). As a result, various portions of the U.S. Treasury market recorded negative returns during the reporting period. Municipal bonds also suffered setbacks from shifting interest rates and

supply-and-demand dynamics. Although insured credits, longer-maturity bonds and taxable municipal securities helped provide positive total returns for municipal bonds overall, municipal bonds with shorter maturities tended to provide negative total returns during the reporting period.

Agency securities posted positive total returns, as did asset-backed securities and most portions of the mortgage-backed securities market. Other bond categories, including high-yield bonds, leveraged loans and corporate bonds generally provided positive returns, while emerging-market debt was generally strong. Convertible bonds, which are closely tied to the performance of underlying stocks, provided some of the strongest overall returns of any fixed-income sector during the reporting period.

The report that follows provides more detailed information on the specific markets, investment strategies and portfolio decisions that affected MainStay DefinedTerm Municipal Opportunities Fund during the six months ended November 30, 2017. We encourage you to read the report carefully and use it to help you evaluate your progress toward your financial goals.

Sincerely,

Kirk C. Lehneis

President

The opinions expressed are as of the date of this report and are subject to change. There is no guarantee that any forecast made will come to pass. This material does not constitute investment advice and is not intended as an endorsement of any specific investment. Past performance is no guarantee of future results.

Not part of the Semiannual Report

Table of Contents

Semiannual Report
Fund Performance and Statistics	5
Portfolio Management Discussion and Analysis	7
Portfolio of Investments	9
Financial Statements	16
Notes to Financial Statements	21
Dividend Reinvestment Plan	29
Proxy Results	30
Proxy Voting Policies and Procedures and Proxy Voting Record	30
Shareholder Reports and Quarterly Portfolio Disclosure	30

Certain material in this report may include statements that constitute “forward-looking statements” under the U.S. securities laws. Forward-looking statements include, among other things, projections, estimates and information about possible or future results or events related to the Fund, market or regulatory developments. The views expressed herein are not guarantees of future performance or economic results and involve certain risks, uncertainties and assumptions that could cause actual outcomes and results to differ materially from the views expressed herein. The views expressed herein are subject to change at any time based upon economic, market, or other conditions and the Fund undertakes no obligation to update the views expressed herein.

Fund Performance and Statistics (Unaudited)

Performance data quoted represents past performance of Common shares of the Fund. Past performance is no guarantee of future results. Because of market volatility and other factors, current performance may be lower or higher than the figures shown. Investment return and principal value will fluctuate, and as a result, when shares are redeemed, they may be worth more or less than their original cost. For performance information current to the most recent month-end, please visit mainstayinvestments.com/mmd.

Total Returns	Six Months			One Year			Five Years			Since Inception 6/26/12
Net Asset Value (“NAV”)1		1.89	%		10.55	%		5.90	%		7.41	%
Market Price1		1.01			13.00			5.74			6.33
Bloomberg Barclays Municipal Bond Index2		0.40			5.58			2.55			3.15
Morningstar Muni National Long Category Average3		1.32			8.00			4.00			5.38

Fund Statistics (as of November 30, 2017)
NYSE Symbol	MMD	Premium/Discount4		–1.95	%
CUSIP	56064K100	Total Net Assets (millions)	$	551.1
Inception Date	6/26/12	Total Managed Assets (millions)5	$	859.2
Market Price	$19.60	Leverage6		35.7	%
NAV	$19.99	Percent of AMT Bonds7		2.22	%

1. Total returns assume dividends and capital gains distributions are reinvested. For periods of less than one year, total return is not annualized.

2. The Bloomberg Barclays Municipal Bond Index is considered representative of the broad market for investment-grade, tax-exempt bonds with a maturity of at least one year. Bonds subject to the alternative minimum tax or with floating or zero coupons are excluded. An investment cannot be made directly in an index.

3. The Morningstar Muni National Long Category Average is representative of funds that invest in bonds issued by various state and local governments to fund public projects. The income from these bonds is generally free from federal taxes. These portfolios have durations of more than 7.0 years. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.

4. Premium/Discount is the percentage (%) difference between the market price and the NAV. When the market price exceeds the NAV, the Fund is

trading at a premium. When the market price is less than the NAV, the Fund is trading at a discount.

5. “Managed Assets” is defined as the Fund’s total assets, minus the sum of its accrued liabilities (other than Fund liabilities incurred for the purpose of creating effective leverage (i.e. tender option bonds) or Fund liabilities related to liquidation preference of any Preferred shares issued).

6. Leverage is based on the use of proceeds received from tender option bond transactions, issuance of Preferred shares, funds borrowed from banks or other institutions or derivative transactions, expressed as a percentage of Managed Assets.

7. Alternative Minimum Tax (“AMT”) is a separate tax computation under the Internal Revenue Code that, in effect, eliminates many deductions and credits and creates a tax liability for an individual who would otherwise pay little or no tax.

5

Portfolio Composition as of November 30, 2017^† (Unaudited)

Puerto Rico (a)	15.3	%
Illinois	14.9
Michigan	10.9
California	10.1
Florida	5.0
Virginia	3.9
New York	3.6
Maryland	2.7
Nebraska	2.6
Texas	2.6
Kansas	2.5
Washington	2.5
Utah	2.4
Pennsylvania	2.2
Guam	2.0
New Jersey	2.0
U.S. Virgin Islands	2.0

Ohio	1.9	%
Rhode Island	1.9
Nevada	1.5
Oklahoma	0.6
Alabama	0.5
District of Columbia	0.4
New Hampshire	0.4
Arizona	0.3
Colorado	0.3
Missouri	0.3
Minnesota	0.2
South Carolina	0.1
Wisconsin	0.1
Georgia	0.0	‡
Other Assets, Less Liabilities	4.3
	100.0	%

See Portfolio of Investments beginning on page 9 for specific holdings within these categories.

Top Ten Holdings or Issuers Held as of November 30, 2017^# (Unaudited)

1. Great Lakes Water Authority, Sewage Disposal System, Revenue Bonds, 5.00%–5.25%, due 7/1/31–7/1/39 (b)

2. Commonwealth of Puerto Rico, Public Improvement, Unlimited General Obligation, 4.50%–6.00%, due 7/1/19–7/1/37 (b)

3. Puerto Rico Highway & Transportation Authority, Revenue Bonds, 4.95%–5.50%, due 7/1/18–7/1/34 (b)

4. County of Orange FL Tourist Development Tax Revenue, Revenue Bonds, 4.00%, due 10/10/33

5. University of California, Regents Medical Center, Revenue Bonds Series J, 5.00%, due 5/15/43

  6. Chicago Board of Education, Unlimited General Obligation, 5.50%–7.00%, due 12/1/39–12/1/44 (b)

  7. Michigan Finance Authority, Trinity Health Corp., Revenue Bonds Series 2016, 5.25%, due 12/1/41

  8. Maryland Health & Higher Educational Facilities Authority, Johns Hopkins Health System Obligated Group, Revenue Bonds Series C, 5.00%, due 5/15/43

  9. Virginia Commonwealth Transportation Board, Capital Projects, Revenue Bonds, 5.00%, due 5/15/31

10. Central Plains Energy, Project No. 3, Revenue Bonds, 5.25%, due 9/1/37

† As a percentage of Managed Assets.

‡ Less than one-tenth of a percent.

# Some of these holdings have been transferred to a Tender Option Bond (“TOB”) Issuer in exchange for the TOB residuals and cash.

(a) As of November 30, 2017, 96% of the Puerto Rico municipal securities held by the Fund were insured and all bonds continue to pay full principal and interest.

(b) Municipal security may feature credit enhancements, such as bond insurance.

6 MainStay DefinedTerm Municipal Opportunities Fund

Portfolio Management Discussion and Analysis (Unaudited)

Questions answered by portfolio managers Robert DiMella, CFA, John Loffredo, CFA, Michael Petty, Scott Sprauer and David Dowden of MacKay Shields LLC, the Fund’s Subadvisor.

How did MainStay DefinedTerm Municipal Opportunities Fund perform relative to its benchmark and peers during the six months ended November 30, 2017?

For the six months ended November 30, 2017, MainStay DefinedTerm Municipal Opportunities Fund returned 1.89% based on net asset value applicable to Common shares and 1.01% based on market price. At net asset value and at market price, the Fund outperformed the 0.40% return of the Bloomberg Barclays Municipal Bond Index.¹ At net asset value, the Fund outperformed—and at market price, the Fund underperformed—the 1.32% return of the Morningstar Muni National Long Category Average² for the six months ended November 30, 2017.

What factors affected the Fund’s relative performance during the reporting period?

The Fund’s performance relative to the Bloomberg Barclays Municipal Bond Index benefited from underweight positions in the tobacco, hospital and local general obligation (G.O.) sectors. The Fund’s relative overweight position in the water/sewer sector also helped performance. Bonds from the Virgin Islands and Puerto Rico came under pressure after two devastating hurricanes hit the region and questions arose about the willingness of issuers to pay debt service amid reconstruction efforts. The Fund’s overweight positions in these two U.S. territories along with its underweight position in the housing sector detracted from the Fund’s relative performance.

What were the most significant factors and risks that influenced the markets in which the Fund invested during the reporting period?

The municipal bond market was broadly influenced during the reporting period by factors that occurred during the six months prior to the reporting period, including the surprise election win of President Trump. His campaign promises to roll back regulation, institute health care reform, reduce corporate and personal taxes, and increase infrastructure spending signaled a dramatic shift in government policy. This policy change was widely interpreted by investors as having a strong impact on future economic growth and inflation, which resulted in an increase in rate volatility immediately following the election. The sell-off that ensued saw the yield curve³ steepen and credit

spreads⁴ widen as investors sought the safety of short-maturing bonds and cash, which led to industrywide redemptions. These redemptions weighed on the most liquid credits as fund managers scrambled to raise cash to meet daily investor withdrawals. Once the calendar year changed to 2017, however, the market began to settle down as industry inflows increased and investors sought to put cash to work. Increasing skepticism over the new president’s ability to affect change in Washington also helped provide positive returns during most of the reporting period as the market began to adjust to a slower-growth trajectory than investors had previously projected and longer-term yields on municipal and U.S. Treasury securities began to trend lower. Toward the end of the reporting period, supply remained manageable and early tax reform proposals benefited municipals, as investors sought to get invested ahead of anticipated strong seasonal demand in the fourth quarter of 2017 and first quarter of 2018.

How was the Fund’s leverage strategy implemented during the reporting period?

The Fund maintained its leverage utilizing tender option bonds (TOBs)⁵ during the reporting period. While the municipal market has witnessed volatility, the yield curve continues to benefit common stock shareholders with an attractive carry on levered assets. The Fund successfully extended its Series A FMTP Shares with Citibank N.A. during the reporting period.

During the reporting period, how was the Fund’s performance materially affected by investments in derivatives?

The Fund employed a duration⁶ hedge utilizing 10-year U.S. Treasury futures. The hedge was used to manage the Fund’s overall duration in relation to the Bloomberg Barclays Municipal Bond Index. The hedge contributed positively to performance.

What was the Fund’s duration strategy during the reporting period?

The Fund’s duration was targeted to remain in a neutral range relative to the Fund’s investable universe as outlined in the prospectus. At the end of the reporting period, the Fund’s

1. See footnote on page 5 for more information on the Bloomberg Barclays Municipal Bond Index.

2. See footnote on page 5 for more information on the Morningstar Muni National Long Category Average.

3. The yield curve is a line that plots the yields of various securities of similar quality—typically U.S. Treasury issues—across a range of maturities. The U.S. Treasury yield curve serves as a benchmark for other debt and is used in economic forecasting.

4. The terms “spread” and “yield spread” may refer to the difference in yield between a security or type of security and comparable U.S. Treasury issues. The terms may also refer to the difference in yield between two specific securities or types of securities at a given time. The term “credit spread” typically refers to the difference in yield between corporate or municipal bonds (or a specific category of these bonds) and comparable U.S. Treasury issues.

5. Tender option bonds are obligations that grant the bondholder the right to require the issuer or a third party (e.g., a tender agent) to purchase the bonds, usually at par, at certain times or under certain conditions prior to maturity. The tender option right is usually available to the investor on a periodic basis. Often, these are floating-rate securities, with the put option exercisable on the dates when the floating rate changes.

6. Duration is a measure of the price sensitivity of a fixed-income investment to changes in interest rates. Duration is expressed as a number of years and is considered a more accurate sensitivity gauge than average maturity.

7

modified duration to worst⁷ was 3.94 years unlevered, or 6.14 years leveraged.

What specific factors, risks or market forces prompted significant investment decisions for the Fund during the reporting period?

During the reporting period, tobacco bonds rallied on strong demand. Well before the reporting period began, the Fund had reduced its exposure to the tobacco sector because of its negative convexity⁸ characteristics. After the municipal market came under significant pressure following the U.S. presidential election, however, the Fund had increased its exposure in tobacco bonds at prices that we believed were much more attractive. As tobacco bonds rallied during the reporting period, they were sold, which added to the Fund’s performance.

Which market segments were the strongest contributors to the Fund’s performance, and which market segments were particularly weak?

The Fund was positioned with a longer-maturity, lower-rating profile than the Bloomberg Barclays Municipal Bond Index, which is entirely made up of investment-grade bonds. (The Fund can invest up to 25% in below-investment-grade bonds.) This strategy underperformed during the first quarter of the reporting period as credit spreads for A, BBB & non-investment-grade rated bonds widened more than those on bonds rated AA and AAA during the municipal bond sell-off.⁹ This trend was broad-based across the entire municipal universe of sectors. During the reporting period these securities outperformed as spreads on lower-rated investment-grade bonds tightened and the yield curve began to flatten. Specifically, the Fund’s exposure to resource recovery bonds and bonds issued in Puerto Rico and the Virgin Islands detracted from performance during the

reporting period. The Fund’s underweight exposure to tobacco-backed, hospital and local G.O. bonds, as well as its overweight position in water/sewer bonds, contributed to the Fund’s performance for the period. (Contributions take weightings and total returns into account.)

Did the Fund make any significant purchases or sales during the reporting period?

As the Fund remains focused on diversification and liquidity, no individual purchase or sale would have been considered significant, although overweight sector positions or positions along the yield curve, in their entirety, would have an impact. Those areas of emphasis have already been discussed.

How did the Fund’s sector weightings change during the reporting period?

As Fund strategy did not materially change from the prior reporting period, there were no major changes to the sector weightings of the Fund.

How was the Fund positioned at the end of the reporting period?

As of November 30, 2017, the Fund held an overweight position relative to the Bloomberg Barclays Municipal Bond Index in bonds with maturities of 10 years or longer. As of the same date, the Fund also held an overweight position relative to the Index in credits rated AA and credits rated BBB and below. As of November 30, 2017, the Fund held approximately 14.7% of its net assets in below-investment-grade municipal credits. At the end of the reporting period, the Fund held underweight positions relative to the Index in securities rated AAA and single A, and in bonds with maturities of less than 10 years.

7. Modified duration is inversely related to the approximate percentage change in price for a given change in yield. Duration to worst is the duration of a bond computed using the bond’s nearest call date or maturity, whichever comes first. This measure ignores future cash flow fluctuations due to embedded optionality.

8. Convexity is a mathematical measure of the sensitivity of an interest-bearing bond to changes in interest rates.

9. An obligation rated ‘AAA’ has the highest rating assigned by Standard & Poor’s (“S&P”), and in the opinion of S&P, the obligor’s capacity to meet its financial commitment on the obligation is extremely strong. An obligation rated ‘AA’ by S&P is deemed by S&P to differ from the highest-rated obligations only to a small degree. In the opinion of S&P, the obligor’s capacity to meet its financial commitment on the obligation is very strong. An obligation rated ‘A’ by S&P is deemed by S&P to be somewhat more susceptible to the adverse effects of changes in circumstances and economic conditions than obligations in higher-rated categories. In the opinion of S&P, however, the obligor’s capacity to meet its financial commitment on the obligation is still strong. An obligation rated ‘BBB’ by S&P is deemed by S&P to exhibit adequate protection parameters. In the opinion of S&P, however, adverse economic conditions or changing circumstances are more likely to lead to a weakened capacity of the obligor to meet its financial commitment on the obligation. When applied to Fund holdings, ratings are based solely on the creditworthiness of the bonds in the portfolio and are not meant to represent the security or safety of the Fund.

The opinions expressed are those of the portfolio managers as of the date of this report and are subject to change. There is no guarantee that any forecasts will come to pass. This material does not constitute investment advice and is not intended as an endorsement of any specific investment.

8 MainStay DefinedTerm Municipal Opportunities Fund

Portfolio of Investments November 30, 2017 (Unaudited)

	Principal Amount		Value
Municipal Bonds 149.2%†
Alabama 0.8% (0.5% of Managed Assets)
Jefferson County, Public Building Authority, Revenue Bonds Insured: AMBAC 5.00%, due 4/1/26	$	4,500,000	$	4,507,560
Arizona 0.4% (0.3% of Managed Assets)
Phoenix Industrial Development Authority, Downtown Phoenix Student LLC, Revenue Bonds Series A, Insured: AMBAC 4.50%, due 7/1/42		150,000		150,006
Phoenix Industrial Development Authority, Espiritu Community Development Corp., Revenue Bonds Series A 6.25%, due 7/1/36		2,000,000		1,999,900
				2,149,906
California 15.8% (10.1% of Managed Assets)
California Health Facilities Financing Authority, Children’s Hospital, Revenue Bonds Series A 5.00%, due 8/15/47		5,000,000		5,700,250
California Municipal Finance Authority, Southwestern Law School, Revenue Bonds 6.50%, due 11/1/41		2,165,000		2,451,819
Ceres Unified School District, Unlimited General Obligation Series A (zero coupon), due 8/1/43		6,375,000		1,143,038
City of Sacramento, California, Water, Revenue Bonds 5.00%, due 9/1/42 (a)		19,500,000		21,984,365
Golden State Tobacco Securitization Corp., Asset-Backed, Revenue Bonds Series A-2 5.30%, due 6/1/37		5,225,000		5,269,726
Riverside County Transportation Commission, Limited Tax, Revenue Bonds Series A 5.25%, due 6/1/39 (a)		19,100,000		22,017,460
Stockton Public Financing Authority, Parking & Capital Projects, Revenue Bonds Insured: NATL-RE 4.80%, due 9/1/20		105,000		105,164

	Principal Amount		Value
California 15.8% (10.1% of Managed Assets) (continued)
Stockton Public Financing Authority, Water System, Capital Improvement Projects, Revenue Bonds Series A, Insured: NATL-RE 5.00%, due 10/1/31	$	140,000	$	140,375
¨University of California, Regents Medical Center, Revenue Bonds Series J 5.00%, due 5/15/43 (a)		23,260,000		26,417,138
Westminster School District, Unlimited General Obligation Series B, Insured: BAM (zero coupon), due 8/1/48		10,000,000		1,575,800
				86,805,135
Colorado 0.5% (0.3% of Managed Assets)
Dominion Water & Sanitation District, Revenue Bonds 6.00%, due 12/1/46		2,500,000		2,605,725
E-470 Public Highway Authority, Revenue Bonds Series B, Insured: NATL-RE (zero coupon), due 9/1/29		660,000		375,118
				2,980,843
District of Columbia 0.6% (0.4% of Managed Assets)
Metropolitan Washington Airports Authority, Revenue Bonds Series C, Insured: AGC 6.50%, due 10/1/41		2,400,000		3,107,400
Florida 7.8% (5.0% of Managed Assets)
Celebration Pointe Community Development District, Special Assessment Revenue Bonds 5.00%, due 5/1/32 (b)		1,400,000		1,464,092
¨County of Orange FL Tourist Development Tax Revenue, Revenue Bonds 4.00%, due 10/10/33 (a)		25,000,000		26,901,797
JEA Electric System, Revenue Bonds Series C 5.00%, due 10/1/37 (a)		12,980,000		14,344,456
				42,710,345
Georgia 0.0%‡ (0.0%‡ of Managed Assets)
Marietta Development Authority, University Facilities-Life University, Inc. Project, Revenue Bonds 6.25%, due 6/15/20		220,000		225,762

† Percentages indicated are based on Fund net assets applicable to Common Shares, unless otherwise noted.

¨ Among the Fund’s 10 largest holdings or issuers held, as of November 30, 2017. May be subject to change daily.

The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements. 9

Portfolio of Investments November 30, 2017 (Unaudited) (continued)

	Principal Amount		Value
Municipal Bonds (continued)
Guam 3.2% (2.0% of Managed Assets)
Guam Government, Business Privilege Tax, Revenue Bonds
5.00%, due 11/15/34	$	1,000,000	$	1,092,380
5.00%, due 1/1/42		3,800,000		3,980,766
Guam Government, Waterworks Authority, Revenue Bonds 5.50%, due 7/1/43		7,550,000		8,460,832
Guam International Airport Authority, Revenue Bonds Series C, Insured: AGM 6.00%, due 10/1/34 (c)		3,425,000		3,964,300
				17,498,278
Illinois 23.2% (14.9% of Managed Assets)
Chicago Board of Education Dedicated Capital Improvement, Special Tax 5.75%, due 4/1/34		8,000,000		9,248,800
Chicago Board of Education Dedicated Capital Improvement, Unlimited General Obligation (b)
Series B 7.00%, due 12/1/42		3,500,000		4,232,480
Series A 7.00%, due 12/1/46		4,000,000		4,822,720
¨Chicago Board of Education, Unlimited General Obligation
Series A, Insured: AGM 5.50%, due 12/1/39 (a)		20,000,000		21,925,100
Series A 7.00%, due 12/1/44		2,880,000		3,382,042
Chicago O’Hare International Airport, Revenue Bonds Insured: AGM 5.75%, due 1/1/38		5,000,000		5,834,750
Chicago, Illinois Wastewater Transmission, Revenue Bonds
Series B. Insured: AGM 5.00%, due 1/1/31		4,140,000		4,733,345
Series C 5.00%, due 1/1/32		7,120,000		7,821,462
Chicago, Illinois, Sales Tax, Revenue Bonds Series A 5.25%, due 1/1/38		7,515,000		7,989,647
Chicago, Unlimited General Obligation
Series C 5.00%, due 1/1/23		300,000		306,840
Series C 5.00%, due 1/1/25		885,000		941,905
Series D 5.00%, due 1/1/29		500,000		509,475

	Principal Amount		Value
Illinois 23.2% (14.9% of Managed Assets) (continued)
Chicago, Unlimited General Obligation (continued)
Series C 5.00%, due 1/1/40	$	10,000,000	$	10,182,100
Series A 5.25%, due 1/1/27		3,000,000		3,304,680
Series A 6.00%, due 1/1/38		2,700,000		3,100,842
Illinois Sports Facilities Authority, Revenue Bonds
Insured: AMBAC (zero coupon), due 6/15/21		410,000		363,231
Insured: AGM 5.00%, due 6/15/29		350,000		383,834
Insured: AGM 5.25%, due 6/15/32		150,000		165,482
Metropolitan Pier & Exposition Authority, McCormick Place Expansion, Revenue Bonds
Series B 5.00%, due 12/15/28		5,000,000		5,370,150
Series A 5.50%, due 6/15/50		8,835,000		9,239,643
Public Building Commission of Chicago, Chicago Transit Authority, Revenue Bonds Insured: AMBAC 5.25%, due 3/1/31		600,000		683,862
Rock Island County IL, Unlimited General Obligation Insured: BAM 4.00%, due 12/1/27		1,730,000		1,862,899
State of Illinois, Unlimited General Obligation 5.25%, due 7/1/31 (a)		20,000,000		21,493,280
				127,898,569
Kansas 3.9% (2.5% of Managed Assets)
Kansas Development Finance Authority, Adventist Health Sunbelt Obligated Group, Revenue Bonds Series A 5.00%, due 11/15/32 (a)		19,290,000		21,518,290
Maryland 4.2% (2.7% of Managed Assets)
¨Maryland Health & Higher Educational Facilities Authority, Johns Hopkins Health System Obligated Group, Revenue Bonds Series C 5.00%, due 5/15/43 (a)		20,870,000		23,296,669

10 MainStay DefinedTerm Municipal Opportunities Fund The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements.

	Principal Amount		Value
Municipal Bonds (continued)
Michigan 16.9% (10.9% of Managed Assets)
¨Great Lakes Water Authority, Sewage Disposal System, Revenue Bonds
Senior Lien-Series C, Insured: AGM 5.00%, due 7/1/31	$	7,500,000	$	8,484,450
Senior Lien-Series A 5.00%, due 7/1/32		1,500,000		1,634,685
Series B, Insured: AGM 5.00%, due 7/1/34 (a)		24,940,000		28,503,801
Senior Lien-Series A 5.25%, due 7/1/39		5,000,000		5,464,050
Great Lakes Water Authority, Water Supply System, Revenue Bonds
Senior Lien-Series C 5.00%, due 7/1/41		1,005,000		1,066,677
Senior Lien-Series A 5.25%, due 7/1/41		2,385,000		2,593,425
Senior Lien-Series A 5.75%, due 7/1/37		5,000,000		5,566,850
Michigan Finance Authority, Public School Academy, University Learning, Revenue Bonds
7.375%, due 11/1/30		2,920,000		3,068,394
7.50%, due 11/1/40		2,745,000		2,880,905
¨Michigan Finance Authority, Trinity Health Corp., Revenue Bonds Series 2016 5.25%, due 12/1/41 (a)		21,630,000		25,153,815
Michigan Public Educational Facilities Authority, Dr. Joseph F. Pollack, Revenue Bonds
8.00%, due 4/1/30		1,195,000		1,269,676
8.00%, due 4/1/40		500,000		529,235
Michigan Tobacco Settlement Finance Authority, Revenue Bonds Series A 6.00%, due 6/1/48		5,000,000		5,013,500
Wayne County Michigan, Capital Improvement, Limited General Obligation Series A, Insured: AGM 5.00%, due 2/1/38		2,135,000		2,144,544
				93,374,007
Minnesota 0.4% (0.2% of Managed Assets)
Blaine Minnesota Senior Housing & Healthcare, Crest View Senior Community Project, Revenue Bonds Series A 5.75%, due 7/1/35		2,000,000		2,050,440

	Principal Amount		Value
Missouri 0.4% (0.3% of Managed Assets)
St. Louis County Industrial Development Authority, Nazareth Living Center, Revenue Bonds 6.125%, due 8/15/42	$	2,120,000	$	2,282,816
Nebraska 4.1% (2.6% of Managed Assets)
¨Central Plains Energy, Project No. 3, Revenue Bonds 5.25%, due 9/1/37 (a)		20,000,000		22,324,800
Nevada 2.3% (1.5% of Managed Assets)
City of Sparks, Tourism Improvement District No. 1, Senior Sales Tax Anticipation, Revenue Bonds Series A 6.75%, due 6/15/28 (b)		12,500,000		12,678,375
New Hampshire 0.6% (0.4% of Managed Assets)
Manchester Housing & Redevelopment Authority, Inc., Revenue Bonds Series B. Insured: ACA (zero coupon), due 1/1/24		4,740,000		3,568,082
New Jersey 3.0% (2.0% of Managed Assets)
New Jersey Economic Development Authority, Continental Airlines, Inc. Project, Revenue Bonds (c)
5.25%, due 9/15/29		6,120,000		6,697,300
Series B 5.625%, due 11/15/30		2,500,000		2,841,650
New Jersey Tobacco Settlement Financing Corp., Revenue Bonds Series 1A 5.00%, due 6/1/41		7,500,000		7,248,525
				16,787,475
New York 5.7% (3.6% of Managed Assets)
New York Liberty Development Corp., World Trade Center, Revenue Bonds Class 3 7.25%, due 11/15/44 (b)		5,500,000		6,596,865
New York Transportation Development Corp., LaGuardia Airport Terminal B Redevelopment Project, Revenue Bonds Series A, Insured: AGM 4.00%, due 7/1/36 (a)		20,000,000		20,857,000
Riverhead Industrial Development Agency, Revenue Bonds 7.00%, due 8/1/43		3,395,000		3,725,741
				31,179,606

The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements. 11

Portfolio of Investments November 30, 2017 (Unaudited) (continued)

	Principal Amount		Value
Municipal Bonds (continued)
Ohio 3.0% (1.9% of Managed Assets)
Buckeye Tobacco Settlement Financing Authority, Asset-Backed, Senior Turbo, Revenue Bonds
Series A-2 5.125%, due 6/1/24	$	2,550,000	$	2,390,268
Series A-2 5.75%, due 6/1/34		2,425,000		2,273,437
Series A-2 5.875%, due 6/1/30		12,200,000		11,617,938
				16,281,643
Oklahoma 1.0% (0.6% of Managed Assets)
Oklahoma Development Finance Authority, Provident OK Educational Resources, Inc. Cross Village Student Housing Project, Revenue Bonds Series A 5.00%, due 8/1/47		5,000,000		5,468,350
Pennsylvania 3.5% (2.2% of Managed Assets)
Harrisburg, Unlimited General Obligation Series F, Insured: AMBAC (zero coupon), due 9/15/21		305,000		260,165
Pennsylvania Economic Development Financing Authority, Capitol Region Parking System, Revenue Bonds Series B 6.00%, due 7/1/53 (a)		14,260,000		16,709,681
Philadelphia Authority for Industrial Development, Nueva Esperanza, Inc., Revenue Bonds 8.20%, due 12/1/43		2,000,000		2,258,800
				19,228,646
Puerto Rico 23.8% (15.3% of Managed Assets)
Children’s Trust Fund Puerto Rico Tobacco Settlement, Revenue Bonds 5.50%, due 5/15/39		5,465,000		5,317,336
Commonwealth of Puerto Rico, Aqueduct & Sewer Authority, Revenue Bonds
Series A, Insured: AGC 5.00%, due 7/1/25		310,000		312,176
Series A, Insured: AGC 5.125%, due 7/1/47		3,340,000		3,358,737
¨Commonwealth of Puerto Rico, Public Improvement, Unlimited General Obligation (d)
Insured: AGM 4.50%, due 7/1/23		280,000		280,784
Series A, Insured: AGM 5.00%, due 7/1/35		19,665,000		20,074,032

	Principal Amount		Value
Puerto Rico 23.8% (15.3% of Managed Assets) (continued)
Commonwealth of Puerto Rico, Public Improvement, Unlimited General Obligation (continued)
Insured: AGM 5.125%, due 7/1/30	$	1,365,000	$	1,373,040
Series A, Insured: AGC 5.25%, due 7/1/23		145,000		147,053
Series A-4, Insured: AGM 5.25%, due 7/1/30		4,425,000		4,663,331
Series A, Insured: AGM 5.375%, due 7/1/25		840,000		899,766
Series A, Insured: AMBAC 5.50%, due 7/1/19		55,000		56,271
Series A, Insured: AGM 5.50%, due 7/1/27		2,230,000		2,390,203
Series A, Insured: AGC 5.50%, due 7/1/32		255,000		260,199
Series C, Insured: AGM 5.50%, due 7/1/32		1,520,000		1,536,477
Series C, Insured: AGM 5.75%, due 7/1/37		5,440,000		5,540,694
Series C-7, Insured: NATL-RE 6.00%, due 7/1/27		2,615,000		2,632,416
Series A, Insured: AGM 6.00%, due 7/1/33		875,000		899,763
Series A, Insured: AGM 6.00%, due 7/1/34		755,000		823,192
Puerto Rico Convention Center District Authority, Revenue Bonds (d)
Series A, Insured: AGC 4.50%, due 7/1/36		8,210,000		8,199,491
Series A, Insured: AGC 5.00%, due 7/1/27		635,000		636,772
Puerto Rico Electric Power Authority, Revenue Bonds (d)
Series DDD, Insured: AGM 3.625%, due 7/1/23		670,000		670,074
Series DDD, Insured: AGM 3.65%, due 7/1/24		2,055,000		2,055,493
Series SS, Insured: NATL-RE 5.00%, due 7/1/19		5,200,000		5,210,712
Series PP, Insured: NATL-RE 5.00%, due 7/1/24		1,100,000		1,100,000
Series PP, Insured: NATL-RE 5.00%, due 7/1/25		165,000		163,160
Series TT, Insured: AGM 5.00%, due 7/1/27		210,000		210,586
Series VV, Insured: AGM 5.25%, due 7/1/27		1,040,000		1,150,344

12 MainStay DefinedTerm Municipal Opportunities Fund The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements.

	Principal Amount		Value
Municipal Bonds (continued)
Puerto Rico 23.8% (15.3% of Managed Assets) (continued)
¨Puerto Rico Highway & Transportation Authority, Revenue Bonds (d)
Series AA-1, Insured: AGM 4.95%, due 7/1/26	$	6,195,000	$	6,429,667
Series K, Insured: AGC, AGM 5.00%, due 7/1/18		560,000		561,887
Series N, Insured: AMBAC 5.25%, due 7/1/30		3,150,000		3,081,299
Series N, Insured: AMBAC 5.25%, due 7/1/31		2,895,000		2,809,308
Series CC, Insured: AGM 5.25%, due 7/1/32		1,570,000		1,730,548
Series N, Insured: NATL-RE 5.25%, due 7/1/32		4,050,000		3,816,234
Series CC, Insured: AGM 5.25%, due 7/1/34		1,950,000		2,138,721
Series N, Insured: AGC 5.25%, due 7/1/34		1,665,000		1,826,139
Series N, Insured: AGC, AGM 5.50%, due 7/1/25		360,000		401,335
Series CC, Insured: AGM 5.50%, due 7/1/29		115,000		129,324
Series N, Insured: AGC, AGM 5.50%, due 7/1/29		5,000,000		5,622,800
Series N, Insured: AMBAC 5.50%, due 7/1/29		965,000		967,422
Series CC, Insured: AGM 5.50%, due 7/1/30		3,185,000		3,584,144
Puerto Rico Infrastructure Financing Authority, Revenue Bonds (d)
Series C, Insured: AMBAC 5.50%, due 7/1/23		1,500,000		1,559,685
Series C, Insured: AMBAC 5.50%, due 7/1/24		235,000		243,413
Series C, Insured: AMBAC 5.50%, due 7/1/25		1,805,000		1,858,825
Series C, Insured: AMBAC 5.50%, due 7/1/26		1,320,000		1,349,396
Puerto Rico Municipal Finance Agency, Revenue Bonds
Series A, Insured: AGM 5.00%, due 8/1/20		590,000		591,870
Series A, Insured: AGM 5.00%, due 8/1/21		810,000		812,568
Series A, Insured: AGM 5.00%, due 8/1/22		810,000		812,568
Series A, Insured: AGM 5.00%, due 8/1/27		2,720,000		2,727,589
Series A, Insured: AGM 5.00%, due 8/1/30		1,205,000		1,207,663

	Principal Amount		Value
Puerto Rico 23.8% (15.3% of Managed Assets) (continued)
Puerto Rico Municipal Finance Agency, Revenue Bonds (continued)
Series A, Insured: AGM 5.25%, due 8/1/21	$	230,000	$	233,981
Series C, Insured: AGC 5.25%, due 8/1/21		3,775,000		4,046,762
Puerto Rico Public Buildings Authority, Government Facilities, Revenue Bonds (d)
Series F, Insured: AGC 5.25%, due 7/1/21		2,000,000		2,140,900
Series M-3, Insured: NATL-RE 6.00%, due 7/1/25		250,000		261,885
Series M-3, Insured: NATL-RE 6.00%, due 7/1/27		10,000,000		10,066,600
Puerto Rico Sales Tax Financing Corp., Revenue Bonds (d) Series A, Insured: NATL-RE (zero coupon), due 8/1/42		870,000		187,337
				131,161,972
Rhode Island 3.0% (1.9% of Managed Assets)
Narragansett Bay Commission Wastewater System, Revenue Bonds Series A 5.00%, due 9/1/38 (a)		15,000,000		16,734,600
South Carolina 0.2% (0.1% of Managed Assets)
South Carolina Public Service Authority, Revenue Bonds Series A 5.00%, due 12/1/31		825,000		940,310
Texas 4.0% (2.6% of Managed Assets)
Harris County-Houston Sports Authority, Revenue Bonds
Series H, Insured: NATL-RE (zero coupon), due 11/15/28		50,000		32,901
Series A, Insured: AGM, NATL-RE (zero coupon), due 11/15/38		175,000		66,420
Series H, Insured: NATL-RE (zero coupon), due 11/15/38		260,000		95,950
Texas Municipal Gas Acquisition & Supply Corp. III, Revenue Bonds 5.00%, due 12/15/32 (a)		20,000,000		21,988,260
				22,183,531

The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements. 13

Portfolio of Investments November 30, 2017 (Unaudited) (continued)

	Principal Amount		Value
Municipal Bonds (continued)
U.S. Virgin Islands 3.1% (2.0% of Managed Assets)
Virgin Islands Public Finance Authority, Gross Receipts Taxes Loan, Revenue Bonds
Series A 5.00%, due 10/1/32	$	3,020,000	$	1,355,225
Series A. Insured: AGM 5.00%, due 10/1/32 (b)		2,590,000		2,733,434
Virgin Islands Public Finance Authority, Matching Fund Loan, Revenue Bonds
Senior Lien-Series A-1 5.00%, due 10/1/24		1,030,000		625,725
Senior Lien-Series B 5.00%, due 10/1/24		700,000		425,250
Series A 5.00%, due 10/1/25		770,000		467,775
Series B 5.25%, due 10/1/29		1,765,000		948,688
Series A 6.625%, due 10/1/29		2,000,000		1,095,000
Virgin Islands Public Finance Authority, Revenue Bonds
Series A 5.00%, due 10/1/29		2,980,000		1,344,725
Series A, Insured: AGM 5.00%, due 10/1/32		5,350,000		5,646,283
Virgin Islands Public Finance Authority, Senior Lien-Matching Fund Loan Note, Revenue Bonds Senior Lien-Series B 5.00%, due 10/1/25		3,890,000		2,363,175
				17,005,280
Utah 3.7% (2.4% of Managed Assets)
County of Utah UT, IHC Health Services, Inc., Revenue Bonds Series B 4.00%, due 5/15/47 (a)		20,000,000		20,655,194
Virginia 6.0% (3.9% of Managed Assets)
Tobacco Settlement Financing Corp., Revenue Bonds Series B1 5.00%, due 6/1/47		5,000,000		4,839,600
¨Virginia Commonwealth Transportation Board, Capital Projects, Revenue Bonds 5.00%, due 5/15/31 (a)		20,315,000		22,912,784
Virginia Small Business Financing Authority, Transform I-66 P3 Project, Revenue Bonds 5.00%, due 12/31/56 (c)		5,000,000		5,541,050
				33,293,434

	Principal Amount			Value
Washington 4.0% (2.5% of Managed Assets)
Washington Health Care Facilities Authority, Multicare Health System, Revenue Bonds Series A 5.00%, due 8/15/44 (a)	$	19,665,000		$	21,860,531
Wisconsin 0.1% (0.1% of Managed Assets)
Public Finance Authority, Bancroft NeuroHealth Project, Revenue Bonds Series A 5.00%, due 6/1/36 (b)		500,000			505,860
Total Investments (Cost $772,838,824)		149.2	%		822,263,709
Floating Rate Note Obligations (e)		(42.9	)		(236,340,000	)
Fixed Rate Municipal Term Preferred Shares, at Liquidation Value		(12.7	)		(70,000,000	)
Other Assets, Less Liabilities		6.4			35,161,762
Net Assets Applicable to Common Shares		100.0	%	$	551,085,471

‡ Less than one-tenth of a percent.

(a) All or portion of principal amount transferred to a Tender Option Bond (“TOB”) Issuer in exchange for TOB Residuals and cash.

(b) May be sold to institutional investors only under Rule 144A or securities offered pursuant to Section 4(a)(2) of the Securities Act of 1933, as amended.

(c) Interest on these securities was subject to alternative minimum tax.

(d) Bond insurance is paying principal and interest, since the issuer is in default.

(e) Face value of Floating Rate Notes issued in TOB transactions.

“Managed Assets” is defined as the Fund’s total assets, minus the sum of its accrued liabilities (other than Fund liabilities incurred for the purpose of creating effective leverage (i.e. tender option bonds) or Fund liabilities related to liquidation preference of any Preferred shares issued), which was $859,200,934 as of November 30, 2017.

The following abbreviations are used in the preceding pages:

ACA—ACA Financial Guaranty Corp.

AGC—Assured Guaranty Corp.

AGM—Assured Guaranty Municipal Corp.

AMBAC—Ambac Assurance Corp.

BAM—Build America Mutual Assurance Co.

NATL-RE—National Public Finance Guarantee Corp.

14 MainStay DefinedTerm Municipal Opportunities Fund The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements.

As of November 30, 2017, the Fund held the following futures contracts¹:

Type	Number of Contracts (Short)			Expiration Date		Value at Trade Date			Current Notional Amount			Unrealized Appreciation (Depreciation)2
10-Year United States Treasury Note		(1,004	)		March 2018	$	(125,215,316	)	$	(124,543,063	)	$	672,253

1. As of November 30, 2017, cash in the amount of $1,054,200 was on deposit with a broker for futures transactions.

2. Represents the difference between the value of the contracts at the time they were opened and the value as of November 30, 2017.

The following is a summary of the fair valuations according to the inputs used as of November 30, 2017, for valuing the Fund’s assets and liabilities.

Asset Valuation Inputs

Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Investments in Securities (a)
Municipal Bonds	$	—	$	822,263,709	$	—	$	822,263,709
Total Investments in Securities		—		822,263,709		—		822,263,709
Other Financial Instruments
Futures Contracts (b)		672,253		—		—		672,253
Total Investments in Securities and Other Financial Instruments	$	672,253	$	822,263,709	$	—	$	822,935,962

(a) For a complete listing of investments and their industries, see the Portfolio of Investments.

(b) The value listed for these securities reflects unrealized appreciation (depreciation) as shown on the Portfolio of Investments.

The Fund recognizes transfers between the levels as of the beginning of the period.

For the period ended November 30, 2017, the Fund did not have any transfers among levels. (See Note 2)

As of November 30, 2017, the Fund did not hold any investments with significant unobservable inputs (Level 3). (See Note 2)

The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements. 15

Statement of Assets and Liabilities as of November 30, 2017 (Unaudited)

Assets
Investment in securities, at value (identified cost $772,838,424)	$	822,263,709
Cash		25,290,540
Cash collateral on deposit at broker for futures contracts		1,054,200
Receivables:
Interest		12,958,944
Investment securities sold		3,008,912
Variation margin on futures contracts		423,563
Other assets		5,663
Total assets		865,005,531
Liabilities
Payable for Floating Rate Note Obligations		236,340,000
Fixed Rate Municipal Term Preferred Shares, at liquidation value, Series A (a)		35,000,000
Fixed Rate Municipal Term Preferred Shares, at liquidation value, Series B (a)		35,000,000
Payables:
Investment securities purchased		5,156,535
Manager (See Note 3)		424,613
Professional fees		46,636
Shareholder communication		17,836
Transfer agent		2,481
Custodian		981
Trustees		44
Accrued expenses		641
Interest expense and fees payable		1,775,463
Common share dividend payable		154,830
Total liabilities		313,920,060
Net assets applicable to Common shares	$	551,085,471
Common shares outstanding		27,562,111
Net asset value per Common share (Net assets applicable to Common shares divided by Common shares outstanding)	$	19.99
Net assets applicable to Common Shares consist of
Common shares, $0.001 par value per share, unlimited number of shares authorized	$	27,562
Additional paid-in capital		524,721,235
		524,748,797
Undistributed net investment income		1,936,091
Accumulated net realized gain (loss) on investments and futures transactions		(25,696,955	)
Net unrealized appreciation (depreciation) on investments and futures contracts		50,097,538
Net assets applicable to Common shares	$	551,085,471

(a) 350 authorized shares, $0.01 par value, liquidation preference of $100,000 per share (See Note 2).

16 MainStay DefinedTerm Municipal Opportunities Fund The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements.

Statement of Operations for the six months ended November 30, 2017 (Unaudited)

Investment Income (Loss)
Income
Interest	$	20,189,361
Expenses
Interest expense and fees		2,641,398
Manager (See Note 3)		2,599,095
Professional fees		62,871
Shareholder communication		22,487
Transfer agent		19,320
Trustees		7,027
Custodian		3,542
Miscellaneous		73,337
Total expenses		5,429,077
Net investment income (loss)		14,760,284
Realized and Unrealized Gain (Loss) on Investments and Futures Contracts
Net realized gain (loss) on:
Investment transactions		(2,148,332	)
Futures transactions		311,541
Net realized gain (loss) on investments and futures transactions		(1,836,791	)
Net change in unrealized appreciation (depreciation) on:
Investments		(3,573,801	)
Futures contracts		1,395,046
Net change in unrealized appreciation (depreciation) on investments and futures contracts		(2,178,755	)
Net realized and unrealized gain (loss) on investments and futures transactions		(4,015,546	)
Net increase (decrease) in net assets to Common shares resulting from operations	$	10,744,738

The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements. 17

Statement of Changes in Net Assets

	Six months ended November 30, 2017*			Year ended May 31, 2017
Net Increase (Decrease) in Net Assets Applicable to Common Shares
Operations:
Net investment income (loss)	$	14,760,284		$	29,615,984
Net realized gain (loss) on investments and futures transactions		(1,836,791	)		11,782,610
Net change in unrealized appreciation (depreciation) on investments and futures contracts		(2,178,755	)		(24,321,046	)
Net increase (decrease) in net assets applicable to Common shares resulting from operations		10,744,738			17,077,548
Dividends to Common shareholders:
From net investment income		(14,882,181	)		(29,979,365	)
Capital share transactions (Common shares):
Net proceeds issued to shareholders resulting from reinvestment of dividends		151,997			—
Increase (decrease) in net assets applicable to Common shares from capital share transactions		151,997			—
Net increase (decrease) in net assets applicable to Common shares		(3,985,446	)		(12,901,817	)
Net Assets Applicable to Common Shares
Beginning of period		555,070,917			567,972,734
End of period	$	551,085,471		$	555,070,917
Undistributed net investment income at end of period	$	1,936,091		$	2,057,988

* Unaudited.

18 MainStay DefinedTerm Municipal Opportunities Fund The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements.

Statement of Cash Flows

for the six months ended November 30, 2017 (Unaudited)

Cash flows used in operating activities:
Net increase in net assets resulting from operations	$	10,744,738
Adjustments to reconcile net increase in net assets resulting from operations to net cash provided by operating activities:
Investments purchased		(54,674,069	)
Investments sold		56,342,897
Amortization (accretion) of discount and premium, net		(586,764	)
Increase in dividends and interest receivable		(636,575	)
Decrease in cash collateral on deposit at broker for future contracts		248,400
Decrease in other assets		26,084
Decrease in professional fees payable		(46,526	)
Increase in custodian payable		275
Decrease in shareholder communication payable		(7,727	)
Increase in due to Trustees		44
Decrease in due to manager		(10,923	)
Decrease in due to transfer agent		(3,715	)
Decrease in variation margin payable on futures contracts		(564,469	)
Decrease in accrued expenses		(5,876	)
Increase in interest expense and fees payable		107,281
Net change in unrealized (appreciation) depreciation on investments		3,573,801
Net realized (gain) loss from investments		2,148,332
Net cash provided by operating activities		16,655,208
Cash flows from financing activities:
Net proceeds resulting from reinvestment of dividends		151,997
Cash distributions paid, net of change in Common share dividend payable		(14,886,926	)
Net cash used in financing activities		(14,734,929	)
Net increase in cash:		1,920,279
Cash at beginning of period		23,370,261
Cash at end of period	$	25,290,540

The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements. 19

Financial Highlights selected per share data and ratios

	Six months ended November 30,			Year ended May 31,												June 26, 2012** through May 31,
	2017*			2017			2016			2015			2014			2013
Net asset value at beginning of period applicable to Common shares	$	20.14		$	20.61		$	19.03		$	18.76		$	19.99		$	19.06	(a)
Net investment income (loss)		0.54			1.08			1.11			1.19			1.16			0.92
Net realized and unrealized gain (loss) on investments		(0.15	)		(0.46	)		1.65			0.25			(0.89	)		1.11
Total from investment operations		0.39			0.62			2.76			1.44			0.27			2.03
Less dividends and distributions to Common shareholders:
From net investment income		(0.54	)		(1.09	)		(1.18	)		(1.17	)		(1.15	)		(0.86	)
From net realized gain on investments		—			—			—			—			(0.35	)		(0.20	)
Dilution effect on net asset value from overallotment issuance		—			—			—			—			—			(0.04	)
Net asset value at end of period applicable to Common shares	$	19.99		$	20.14		$	20.61		$	19.03		$	18.76		$	19.99
Market price at end of period applicable to Common shares	$	19.60		$	19.94		$	19.66		$	18.43		$	17.93		$	18.91
Total investment return (b)		1.89	%		3.21	%		15.02	%		7.78	%		2.36	%		10.52	%
Total investment return on market price (b)		1.01	%		7.22	%		13.66	%		9.60	%		3.81	%		(0.36	%)
Ratios (to average net assets of Common shareholders)/Supplemental Data:
Net investment income (loss)		5.29	%††		5.35	%		5.73	%		6.17	%		6.67	%		5.01	% ††
Net expenses (excluding interest expense and fees)		1.00	%††		0.98	%		0.99	%		0.99	%		1.02	%		0.89	% ††(c)
Expenses (including interest expense and fees)		1.95	%††		1.83	%		1.58	%		1.56	%		1.67	%		1.32	% ††(c)
Interest expense and fees (d)		0.95	%††		0.85	%		0.59	%		0.57	%		0.65	%		0.43	% ††
Portfolio turnover rate		6	%		26	%		30	%		27	%		83	%		64	%
Net assets applicable to Common shareholders end of period (in 000’s)	$	551,085		$	555,071		$	567,973		$	524,395		$	516,960		$	550,767
Preferred shares outstanding at $100,000 liquidation preference, end of period (in 000’s)	$	70,000		$	70,000		$	70,000		$	70,000		$	70,000		$	70,000
Assets coverage per Preferred share, end of period (e)	$	887,265		$	892,958		$	911,390		$	849,136		$	838,514		$	886,811
Average market value per Preferred share:
Series A	$	100,012		$	100,012		$	100,015		$	100,010		$	100,006		$	100,008
Series B	$	100,000		$	100,000		$	100,087		$	100,012		$	100,006		$	100,007

* Unaudited.

** Inception date.

†† Annualized.

(a) Net asset value at beginning of period reflects the deduction of the sales load of $0.90 per share and offering costs of $0.04 per share from the $20.00 offering price.

(b) Total investment return assumes the reinvestment of dividends and distributions. For periods less than one year, total return is not annualized.

(c) The Manager has agreed to reimburse all organizational expenses.

(d) Interest expense and fees relate to the costs of tender option bond transactions (See Note 2 (I)) and the issuance of fixed rate municipal term preferred shares (See Note 2 (J)).

(e) Calculated by subtracting the Fund’s total liabilities (not including the Preferred shares) from the Fund’s total assets, and dividing the result by the number of Preferred shares outstanding.

20 MainStay DefinedTerm Municipal Opportunities Fund The notes to the financial statements are an integral part of,
and should be read in conjunction with, the financial statements.

Notes to Financial Statements (Unaudited)

Note 1–Organization and Business

MainStay DefinedTerm Municipal Opportunities Fund (the “Fund”) was organized as a Delaware statutory trust on April 20, 2011, pursuant to an agreement and declaration of trust, which was amended and restated on May 16, 2012 (“Declaration of Trust”). The Fund is registered under the Investment Company Act of 1940, as amended (the “1940 Act”), as a “diversified”, closed-end management investment company, as those terms are defined in the 1940 Act, as interpreted or modified by regulatory authorities having jurisdiction, from time to time. The Fund first offered Common shares through an initial public offering on June 26, 2012.

Pursuant to the terms of the Declaration of Trust, the Fund will commence the process of liquidation and dissolution at the close of business on December 31, 2024 (the “Termination Date”) unless otherwise extended by a majority of the Board of Trustees (the “Board”) (as discussed in further detail below). During the six-month period preceding the Termination Date or Extended Termination Date (as defined below), the Board may, without shareholder approval unless such approval is required by the 1940 Act, determine to (i) merge or consolidate the Fund so long as the surviving or resulting entity is an open-end registered investment company that is managed by the same investment adviser which serves as the investment adviser to the Fund at that time or is an affiliate of such investment adviser; or (ii) convert the Fund from a closed-end fund into an open-end registered investment company. Upon liquidation and termination of the Fund, shareholders will receive an amount equal to the Fund’s net asset value (“NAV”) at that time, which may be greater or less than the price at which Common shares were issued. The Fund’s investment objectives and policies are not designed to return to investors who purchased Common shares in the initial offering of such shares their initial investment on the Termination Date and such initial investors may receive more or less than their original investment upon termination.

Prior to the commencement of the six-month period preceding the Termination Date, a majority of the Board may extend the Termination Date for a period of not more than two years or such shorter time as may be determined (the “Extended Termination Date”), upon a determination that taking such actions as described in (i) or (ii) above would not, given prevailing market conditions, be in the best interests of the Fund’s shareholders. The Termination Date may be extended an unlimited number of times by the Board prior to the first business day of the sixth month before the next occurring Extended Termination Date.

The Fund’s primary investment objective is to seek current income exempt from regular U.S. Federal income taxes (but which may be includable in taxable income for purpose of the Federal alternative minimum tax). Total return is a secondary objective.

Note 2–Significant Accounting Policies

The Fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (“FASB”) Accounting Standard Codification Topic 946 Financial Services—Investment Companies. The Fund prepares its financial statements in accordance with generally accepted accounting principles (“GAAP”) in the United States of America and follows the significant accounting policies described below.

(A)  Securities Valuation.  Investments are usually valued as of the close of regular trading on the New York Stock Exchange (the “Exchange”) (usually 4:00 p.m. Eastern time) on each day the Fund is open for business (“valuation date”).

The Board adopted procedures establishing methodologies for the valuation of the Fund’s securities and other assets and delegated the responsibility for valuation determinations under those procedures to the Valuation Committee of the Fund (the “Valuation Committee”). The Board authorized the Valuation Committee to appoint a Valuation Subcommittee (the “Subcommittee”) to deal in the first instance with establishing the prices of securities for which market quotations are not readily available or the prices of which are not otherwise readily determinable under these procedures. The Subcommittee meets (in person, via electronic mail or via teleconference) on an as-needed basis. Subsequently, the Valuation Committee meets to ensure that actions taken by the Subcommittee were appropriate. The procedures state that, subject to the oversight of the Board and unless otherwise noted, the responsibility for the day-to-day valuation of portfolio assets (including fair value measurements for the Fund’s assets and liabilities) rests with New York Life Investment Management LLC (“New York Life Investments” or the “Manager”), aided to whatever extent necessary by the Subadvisor (as defined in Note 3(A)).

To assess the appropriateness of security valuations, the Manager, the Subadvisor or the Fund’s third party service provider, who is subject to oversight by the Manager, regularly compares prior day prices, prices on comparable securities, and the sale prices to the prior and current day prices and challenges prices with changes exceeding certain tolerance levels with third party pricing services or broker sources. For those securities valued through either a standardized fair valuation methodology or a fair valuation measurement, the Subcommittee deals in the first instance with such valuation and the Valuation Committee reviews and affirms, if appropriate, the reasonableness of the valuation based on such methodologies and measurements on a regular basis after considering information that is reasonably available and deemed relevant by the Valuation Committee. Any action taken by the Subcommittee with respect to the valuation of a portfolio security or other asset is submitted for review and ratification (if appropriate) to the Valuation Committee and the Board at the next regularly scheduled meeting.

“Fair value” is defined as the price the Fund would reasonably expect to receive upon selling an asset or liability in an orderly transaction to an independent buyer in the principal or most advantageous market for the asset or liability. Fair value measurements are determined within a framework that establishes a three-tier hierarchy which maximizes the use of observable market data and minimizes the use of unobservable inputs to establish a classification of fair value measurements for disclosure purposes. “Inputs” refer broadly to the assumptions that market participants would use in pricing the asset or liability, including assumptions about risk, such as the risk inherent in a particular valuation technique used to measure fair value using a pricing model and/or the risk inherent in the inputs for the valuation technique. Inputs may be observable or unobservable. Observable inputs reflect the assumptions market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Fund. Unobservable inputs reflect the Fund’s own assumptions about the assumptions market participants would use in pricing the asset or

21

Notes to Financial Statements (Unaudited) (continued)

liability based on the information available. The inputs or methodology used for valuing assets or liabilities may not be an indication of the risks associated with investing in those assets or liabilities. The three-tier hierarchy of inputs is summarized below.

• Level 1—quoted prices in active markets for an identical asset or liability

• Level 2—other significant observable inputs (including quoted prices for a similar asset or liability in active markets, interest rates and yield curves, prepayment speeds, credit risk, etc.)

• Level 3—significant unobservable inputs (including the Fund’s own assumptions about the assumptions that market participants would use in measuring fair value of an asset or liability)

The level of an asset or liability within the fair value hierarchy is based on the lowest level of an input, both individually and in the aggregate, that is significant to the fair value measurement. As of November 30, 2017, the aggregate value by input level of the Fund’s assets and liabilities is included at the end of the Fund’s Portfolio of Investments.

The Fund may use third-party vendor evaluations, whose prices may be derived from one or more of the following standard inputs, among others:

•    Benchmark yields	•    Reported trades
•    Broker/dealer quotes	•    Issuer spreads
•    Two-sided markets	•    Benchmark securities
•    Bids/offers	•    Reference data (corporate actions or material event notices)
•    Industry and economic events	•    Comparable bonds
•    Monthly payment information

An asset or liability for which market values cannot be measured using the methodologies described above is valued by methods deemed reasonable in good faith by the Valuation Committee, following the procedures established by the Board, to represent fair value. Under these procedures, the Fund generally uses a market-based approach which may use related or comparable assets or liabilities, recent transactions, market multiples, book values, and other relevant information. The Fund may also use an income-based valuation approach in which the anticipated future cash flows of the asset or liability are discounted to calculate fair value. Discounts may also be applied due to the nature and/or duration of any restrictions on the disposition of the asset or liability. Fair value represents a good faith approximation of the value of a security. Fair value determinations involve the consideration of a number of subjective factors, an analysis of applicable facts and circumstances and the exercise of judgment. As a result, it is possible that the fair value for a security determined in good faith in accordance with the Fund’s valuation procedures may differ from valuations for the same security determined by other funds using their own valuation procedures. Although the Fund’s valuation procedures are designed to value a security at the price the Fund may reasonably expect to receive upon the security’s sale in an orderly transaction, there can be no assurance that any fair value determination thereunder would, in fact, approximate the amount that the Fund would actually realize upon the sale of the security or the price at which the security would trade if a reliable market price were readily available. During the six-month period

ended November 30, 2017, there were no material changes to the fair value methodologies.

Securities which may be valued in this manner include, but are not limited to: (i) a security for which trading has been halted or suspended; (ii) a debt security that has recently gone into default and for which there is not a current market quotation; (iii) a security of an issuer that has entered into a restructuring; (iv) a security that has been de-listed from a national exchange; (v) a security for which the market price is not readily available from a third-party pricing source or, if so provided, does not, in the opinion of the Manager or Subadvisor, reflect the security’s market value; (vi) a security subject to trading collars for which no or limited trading takes place; and (vii) a security whose principal market has been temporarily closed at a time when, under normal conditions, it would be open. Securities for which market quotations or observable inputs are not readily available are generally categorized as Level 3 in the hierarchy. As of November 30, 2017, there were no securities held by the Fund that were fair valued in such a manner.

Futures contracts are valued at the last posted settlement price on the market where such futures are primarily traded and are generally categorized as Level 1 in the hierarchy.

Municipal debt securities are valued at the evaluated mean prices supplied by a pricing agent or broker selected by the Manager, in consultation with the Subadvisor. Those values reflect broker/dealer supplied prices and electronic data processing techniques, if the evaluated bid or mean prices are deemed by the Manager, in consultation with the Subadvisor, to be representative of market values, at the regular close of trading of the Exchange on each valuation date. Debt securities purchased on a delayed delivery basis are marked to market daily until settlement at the forward settlement date. Municipal debt securities are generally categorized as Level 2 in the hierarchy.

Temporary cash investments acquired in excess of 60 days to maturity at the time of purchase are valued using the latest bid prices or using valuations based on a matrix system (which considers such factors as security prices, yields, maturities and ratings), both as furnished by independent pricing services. Other temporary cash investments which mature in 60 days or less at the time of purchase (“Short-Term Investments”) are valued using the amortized cost method of valuation, unless the use of such method would be inappropriate. The amortized cost method involves valuing a security at its cost on the date of purchase and thereafter assuming a constant amortization to maturity of the difference between such cost and the value on maturity date. Amortized cost approximates the current fair value of a security. Securities valued using the amortized cost method are not valued using quoted prices in an active market and are generally categorized as Level 2 in the hierarchy.

The information above is not intended to reflect an exhaustive list of the methodologies that may be used to value portfolio investments. The valuation procedures permit the use of a variety of valuation methodologies in connection with valuing portfolio investments. The methodology used for a specific type of investment may vary based on the market data available or other considerations. The methodologies summarized above may not represent the specific means by which portfolio investments are valued on any particular business day.

22 MainStay DefinedTerm Municipal Opportunities Fund

(B)  Income Taxes.  The Fund’s policy is to comply with the requirements of the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”), applicable to regulated investment companies and to distribute all of its taxable income to the shareholders of the Fund within the allowable time limits. Therefore, no federal, state and local income tax provisions are required.

Management evaluates the Fund’s tax positions to determine if the tax positions taken meet the minimum recognition threshold in connection with accounting for uncertainties in income tax positions taken or expected to be taken for the purposes of measuring and recognizing tax liabilities in the financial statements. Recognition of tax benefits of an uncertain tax position is permitted only to the extent the position is “more likely than not” to be sustained assuming examination by taxing authorities. Management has analyzed the Fund’s tax positions taken on federal, state and local income tax returns for all open tax years (for up to three tax years), and has concluded that no provisions for federal, state and local income tax are required in the Fund’s financial statements. The Fund’s federal, state and local income and federal excise tax returns for tax years for which the applicable statutes of limitations have not expired are subject to examination by the Internal Revenue Service and state and local departments of revenue.

(C)  Dividends and Distributions to Common Shareholders.   Dividends and distributions are recorded on the ex-dividend date. The Fund intends to declare dividends from net investment income, after payment of any dividends on any outstanding Preferred shares, if any, at least monthly and declares and pays distributions from net realized capital gains, if any, at least annually. To the extent that the Fund realizes any capital gains or ordinary taxable income, it will be required to allocate such income between the Common shares and Preferred shares issued by the Fund, in proportion to the total dividends paid to each share class for the year in which the income is realized.

(D)  Security Transactions and Investment Income.  The Fund records security transactions on the trade date. Realized gains and losses on security transactions are determined using the identified cost method. Interest income is accrued as earned using the effective interest rate method. Discounts and premiums on securities purchased, other than Short-Term Investments, for the Fund are accreted and amortized, respectively, on the effective interest rate method over the life of the respective securities. Discounts and premiums on Short-Term Investments are accreted and amortized, respectively, on the straight-line method. The straight-line method approximates the effective interest method for Short-Term Investments.

The Fund may place a debt security on non-accrual status and reduce related interest income by ceasing current accruals and writing off all or a portion of any interest receivables when the collection of all or a portion of such interest has become doubtful. A debt security is removed from non-accrual status when the issuer resumes interest payments or when collectability of interest is reasonably assured.

(E)  Expenses.  Expenses of the Fund are recorded on the date the expenses are incurred. The expenses borne by the Fund, including those of related parties to the Fund, are shown in the Statement of Operations.

(F)  Use of Estimates.  In preparing financial statements in conformity with GAAP, management makes estimates and assumptions that

affect the reported amounts and disclosures in the financial statements. Actual results could differ from those estimates.

(G)  Futures Contracts.  A futures contract is an agreement to purchase or sell a specified quantity of an underlying instrument at a specified future date and price, or to make or receive a cash payment based on the value of a financial instrument (e.g., foreign currency, interest rate, security or securities index). The Fund is subject to risks such as market price risk and/or interest rate risk in the normal course of investing in these transactions. Upon entering into a futures contract, the Fund is required to pledge to the broker or futures commission merchant an amount of cash and/or U.S. Government securities equal to a certain percentage of the collateral amount, known as the “initial margin.” During the period the futures contract is open, changes in the value of the contract are recognized as unrealized appreciation or depreciation by marking to market such contract on a daily basis to reflect the market value of the contract at the end of each day’s trading. The Fund agrees to receive from or pay to the broker or futures commission merchant an amount of cash equal to the daily fluctuation in the value of the contract. Such receipts or payments are known as “variation margin.” When the futures contract is closed, the Fund records a realized gain or loss equal to the difference between the proceeds from (or cost of) the closing transaction and the Fund’s basis in the contract.

The use of futures contracts involves, to varying degrees, elements of market risk in excess of the amount recognized in the Statement of Assets and Liabilities. The contract or notional amounts and variation margin reflect the extent of the Fund’s involvement in open futures positions. There are several risks associated with the use of futures contracts as hedging techniques. There can be no assurance that a liquid market will exist at the time when the Fund seeks to close out a futures contract. If no liquid market exists, the Fund would remain obligated to meet margin requirements until the position is closed. Futures may involve a small initial investment relative to the risk assumed, which could result in losses greater than if they had not been used. Futures may be more volatile than direct investments in the instrument underlying the futures and may not correlate to the underlying instrument, causing a given hedge not to achieve its objectives. The Fund’s activities in futures contracts have minimal counterparty risk as they are conducted through regulated exchanges that guarantee the futures against default by the counterparty. In the event of a bankruptcy or insolvency of a futures commission merchant that holds margin on behalf of the Fund, the Fund may not be entitled to the return of the entire margin owed to the Fund, potentially resulting in a loss. The Fund may invest in futures contracts to seek enhanced returns or to reduce the risk of loss by hedging certain of its holdings. The Fund’s investment in futures contracts and other derivatives may increase the volatility of the Fund’s NAV and may result in a loss to the Fund. As of November 30, 2017, all open futures contracts are shown in the Portfolio of Investments.

(H)  Securities Lending.  In order to realize additional income, the Fund may engage in securities lending, subject to the limitations set forth in the 1940 Act and relevant guidance by the staff of the Securities and Exchange Commission (“SEC”). In the event the Fund does engage in securities lending, the Fund will lend through its custodian, State Street Bank and Trust Company (“State Street”). State Street will

23

Notes to Financial Statements (Unaudited) (continued)

manage the Fund’s collateral in accordance with the lending agreement between the Fund and State Street, and indemnify the Fund against counterparty risk. The loans will be collateralized by U.S. Treasury securities at least equal at all times to the market value of the securities loaned. The Fund may bear the risk of delay in recovery of, or loss of rights in, the securities loaned should the borrower of the securities experience financial difficulty. The Fund may also record a realized gain or loss on securities deemed sold due to a borrower’s inability to return securities on loan. The Fund bears the risk of any loss on investment of the collateral. The Fund will receive compensation for lending its securities in the form of fees or it will retain a portion of interest on the investment of any cash received as collateral. The Fund will also continue to receive interest and dividends on the securities loaned and any gain or loss in the market price of the securities loaned that may occur during the term of the loan will be for the account of the Fund. During the six-month period ended November 30, 2017, the Fund did not have any portfolio securities on loan.

(I)  Tender Option Bonds.  The Fund may leverage its assets through the use of proceeds received from tender option bond (“TOB”) transactions. In a TOB transaction, a tender option bond trust (a “TOB Issuer”) is typically established, which forms a special purpose trust into which the Fund, or an agent on behalf of the Fund, transfers municipal bonds or other municipal securities (“Underlying Securities”). A TOB Issuer typically issues two classes of beneficial interests: short-term floating rate notes (“TOB Floaters”) with a fixed principal amount representing a senior interest in the Underlying Securities, and which are sold to third party investors, and residual interest municipal tender option bonds (“TOB Residuals”) representing a subordinate interest in the Underlying Securities, and which are generally issued to the Fund. The interest rate on the TOB Floaters resets periodically, usually weekly, to a prevailing market rate, and holders of the TOB Floaters are granted the option to tender their TOB Floaters back to the TOB Issuer for repurchase at their principal amount plus accrued interest thereon periodically, usually daily or weekly. The Fund may invest in both TOB Floaters and TOB Residuals. The Fund may not invest more than 5% of its Managed Assets (as defined in Note 3(A)) in any single TOB Issuer. The Fund may invest in both TOB Floaters and TOB Residuals issued by the same TOB Issuer.

Historically, the TOB Issuers in which the Fund has invested have been sponsored by banking entities. However, it is no longer practical for banking entities to perform this role due to Section 619 of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the rules thereunder (collectively, the “Volcker Rule”). The Volcker Rule generally prohibits banking entities from engaging in proprietary trading or from acquiring or retaining an ownership interest in, or sponsoring, a hedge fund or private equity fund (“covered fund”), subject to certain exemptions and limitations on those exemptions, as defined in the Rule. TOB programs generally are considered to be covered funds under the Volcker Rule, and, thus, may not be sponsored by a banking entity absent an applicable exemption. The Volcker Rule does not provide for any exemption that would allow banking entities to sponsor TOBs in the same manner as they did prior to the Volcker Rule’s effectiveness and compliance date, which was July 21, 2017.

As a result of the Volcker Rule, a new structure for TOBs has been designed wherein a banking entity does not serve as the sponsor of the

TOB Issuer, but rather a fund serves as the sponsor of the TOB issuer (“Fund-sponsored TOB”). Under this structure, a fund establishes, structures and “sponsors” the TOB Issuer in which it holds TOB Residuals. Certain responsibilities that previously belonged to a third-party banking entity are performed by, or on behalf of, the fund sponsoring the Fund-sponsored TOB. The Fund’s investments in TOBs that were sponsored by banking entities, have been restructured using this Fund-sponsored structure. The Fund uses this or a similar structure for any TOB in which it invests. In connection with Fund-sponsored TOBs, the Fund may contract with a third-party to perform some or all of the Fund’s duties as sponsor. Regardless of whether the Fund delegates any of its sponsorship duties to a third party, the Fund’s expanded role under the Fund-sponsored TOB structure may increase its operational and regulatory risk. If the third-party is unable to perform its obligations as an administrative agent, the Fund itself would be subject to such obligations or would need to secure a replacement agent. The obligations that the Fund may be required to undertake could include reporting and recordkeeping obligations under the Internal Revenue Code and federal securities laws and contractual obligations with other TOB service providers. The effectiveness of the new Fund-sponsored TOB structure is uncertain. There is a risk that the Fund-sponsored TOB structure will not prove as effective a source of leverage for the Fund, which could adversely affect Fund performance.

Under the Fund-sponsored TOB structure, the TOB Issuer receives Underlying Securities from the Fund through (or as) the sponsor and then issues TOB Floaters to third party investors and TOB Residuals to the Fund. The Fund is paid the cash (less transaction expenses, which are borne by the Fund) received by the TOB Issuer from the sale of TOB Floaters and typically will invest the cash in additional municipal bonds or other investments permitted by its investment policies. TOB Floaters may have first priority on the cash flow from the securities held by the TOB Issuer and are enhanced with a liquidity support arrangement from a bank or an affiliate of the sponsor (the “liquidity provider”), which allows holders to tender their position back to the TOB Issuer at par (plus accrued interest). The Fund, in addition to receiving cash from the sale of TOB Floaters, also receives TOB Residuals. TOB Residuals provide the Fund with the right to (1) cause the holders of TOB Floaters to tender their notes to the TOB Issuer at par (plus accrued interest), and (2) acquire the Underlying Securities from the TOB Issuer. In addition, all voting rights and decisions to be made with respect to any other rights relating to the Underlying Securities deposited in the TOB Issuer are passed through to the Fund, as the holder of TOB Residuals. Such a transaction, in effect, creates exposure for the Fund to the entire return of the Underlying Securities deposited in the TOB Issuer, with a net cash investment by the Fund that is less than the value of the Underlying Securities deposited in the TOB Issuer. This multiplies the positive or negative impact of the Underlying Securities’ return within the Fund (thereby creating leverage). Income received from TOB Residuals will vary inversely with the short term rate paid to holders of TOB Floaters and in most circumstances, TOB Residuals present substantially all of the Underlying Securities’ downside investment risk and also benefits disproportionately from any potential appreciation of the Underlying Securities’ value. The amount of such increase or decrease is a function, in part, of the amount of TOB Floaters sold by the TOB Issuer of these securities relative to the amount of TOB Residuals that it sells. The greater the amount of TOB Floaters sold relative to TOB Residuals,

24 MainStay DefinedTerm Municipal Opportunities Fund

the more volatile the income paid on TOB Residuals will be. The price of TOB Residuals will be more volatile than that of the Underlying Securities because the interest rate is dependent on not only the fixed coupon rate of the Underlying Securities, but also on the short-term interest rate paid on TOB Floaters.

For TOB Floaters, generally, the interest rate earned will be based upon the market rates for municipal securities with maturities or remarketing provisions that are comparable in duration to the periodic interval of the tender option, which may vary from weekly, to monthly, to extended periods of one year or multiple years. Since the option feature has a shorter term than the final maturity or first call date of the Underlying Securities deposited in the TOB Issuer, the Fund, if it is the holder of the TOB Floaters, relies upon the terms of the agreement with the financial institution furnishing the option as well as the credit strength of that institution. As further assurance of liquidity, the terms of the TOB Issuer provide for a liquidation of the Underlying Security deposited in the TOB Issuer and the application of the proceeds to pay off the TOB Floaters.

The TOB Issuer may be terminated without the consent of the Fund upon the occurrence of certain events, such as the bankruptcy or default of the issuer of the Underlying Securities deposited in the TOB Issuer, a substantial downgrade in the credit quality of the issuer of the securities deposited in the TOB Issuer, the inability of the TOB Issuer to obtain liquidity support for the TOB Floaters, a substantial decline in the market value of the Underlying Securities deposited in the TOB Issuer, or the inability of the sponsor to remarket any TOB Floaters tendered to it by holders of the TOB Floaters. In such an event, the TOB Floaters would be redeemed by the TOB Issuer at par (plus accrued interest) out of the proceeds from a sale of the Underlying Securities deposited in the TOB Issuer. If this happens, the Fund would be entitled to the assets of the TOB Issuer, if any, that remain after the TOB Floaters have been redeemed at par (plus accrued interest). If there are insufficient proceeds from the sale of these Underlying Securities to redeem all of the TOB Floaters at par (plus accrued interest), the liquidity provider or holders of the TOB Floaters would bear the losses on those securities and there would be no recourse to the Fund’s assets (unless the Fund held a recourse TOB Residual).

Pursuant to the Volcker Rule, to the extent that the remarketing agent is a banking entity, it would not be able to repurchase tendered TOB Floaters for its own account upon a failed remarketing. In the event of a failed remarketing, a banking entity serving as liquidity provider may loan the necessary funds to the TOB Issuer to purchase the tendered TOB Floaters. The TOB Issuer, not the Fund, would be the borrower and the loan from the liquidity provider will be secured by the purchased TOB Floaters now held by the TOB Issuer. However, the Fund would bear the risk of loss with respect to any liquidity shortfall to the extent it entered into a reimbursement agreement with the liquidity provider.

For financial reporting purposes, Underlying Securities that are deposited into a TOB Issuer are treated as investments of the Fund, and are presented in the Fund’s Portfolio of Investments. Outstanding TOB Floaters issued by a TOB Issuer are presented as a liability at their face value as “Payable for Floating Rate Note Obligations” in the Fund’s Statement of Assets and Liabilities. The face value of the TOB Floaters approximates their fair value of the floating rate notes. Interest income from the Underlying Securities are recorded by the Fund on an accrual basis. Interest expense incurred on the TOB Floaters and other

expenses related to remarketing, administration and trustee services to a TOB Issuer are recognized as a component of “Interest expense and fees” in the Statement of Operations.

At November 30, 2017, the aggregate value of the Underlying Securities transferred to the TOB Issuer and the related liability for TOB Floaters were as follows:

Underlying Securities Transferred to TOB Issuers	Liability for Floating Rate Note Obligations
$417,599,022	$236,340,000

During the six-month period ended November 30, 2017, the Fund’s average TOB Floaters outstanding and the daily weighted average interest rate, including fees, were as follows:

Average Floating Rate Note Obligations Outstanding	Daily Weighted Average Interest Rate
$236,340,000	0.82%

(J)  Fixed Rate Municipal Term Preferred Shares.  On October 4, 2012, the Fund issued and has outstanding, two series of Fixed Rate Municipal Term Preferred Shares (“Series A FMTP Shares” and “Series B FMTP Shares”, collectively, “FMTP Shares”), each with a liquidation preference of $100,000 per share (“Liquidation Preference”). Dividends on FMTP Shares, which are recognized as interest expense for financial reporting purposes, are paid semiannually at a fixed annual rate, subject to adjustments in certain circumstances. The FMTP Shares were issued in a private offering exempt from registration under the Securities Act of 1933, as amended.

The Fund is obligated to redeem its FMTP Shares by the date as specified in its offering document (“Term Redemption”), unless redeemed earlier by the Fund. FMTP Shares are subject to optional and mandatory redemption in certain circumstances. FMTP Shares will be subject to redemption, at the option of the Fund (“Optional Redemption”), in whole or in part at any time only for the purposes of decreasing leverage of the Fund. The Fund may be obligated to redeem certain of the FMTP Shares if the Fund fails to maintain certain asset coverage and leverage ratio requirements and such failures are not cured by the applicable cure date. The Optional Redemption price per share is equal to the sum of the Liquidation Preference per share plus any accrued but unpaid dividends.

As of November 30, 2017, the number of FMTP Shares outstanding and annual dividend rate were as follows:

Series	Dates of Issuance	Shares Outstanding		Annual Dividend Rate
A	October 4, 2012 (a)		350		2.78	%
B	October 4, 2012		350		1.89	%

(a) Effective November 30, 2017, the Board agreed to extend the Term Redemption date and revise the annual dividend rate of the Series A FMTP Shares. Prior to November 30, 2017, the Term Redemption date was May 31, 2018 and the annual dividend rate was 2.07%.

25

Notes to Financial Statements (Unaudited) (continued)

As of November 30, 2017, the Term Redemption date and liquidation value for the FMTP Shares outstanding were as follows:

Series	Term Redemption Date	Liquidation Value
A	November 30, 2020	$	35,332,753
B	November 30, 2018	$	35,303,187

For financial reporting purposes only, the liquidation value of FMTP Shares is recorded as a liability on the Statement of Assets and Liabilities. Unpaid dividends on FMTP Shares are recognized as a component of “Interest expense and fees payable” on the Statement of Assets and Liabilities. Dividends accrued on FMTP Shares are recognized as a component of “Interest expense and fees” in the Statement of Operations.

(K)  Statement of Cash Flows.  The cash amount shown in the Fund’s Statement of Cash Flows is the amount included in the Fund’s Statement of Assets and Liabilities and represents the cash on hand at its custodian.

(L)  Municipal Bond Risk.  The Fund may invest more heavily in municipal bonds from certain cities, states, territories, or regions than others, which may increase the Fund’s exposure to losses resulting from economic, political, or regulatory occurrences impacting these particular cities, states, territories or regions. In addition, many state and municipal governments that issue securities are under significant economic and financial stress and may not be able to satisfy their obligations. The Fund may invest a substantial amount of its assets in municipal bonds whose interest is paid solely from revenues of similar projects, such as tobacco settlement bonds. If the Fund concentrates its investments in this manner, it assumes the legal and economic risks relating to such projects and this may have a significant impact on the Fund’s investment performance.

Certain of the issuers in which the Fund may invest have recently experienced, or may experience, significant financial difficulties and repeated credit rating downgrades. On May 3, 2017, the Commonwealth of Puerto Rico began proceedings to seek bankruptcy-type protections from approximately $74 billion in debt and approximately $48 billion in unfunded pension obligations. Puerto Rico’s debt restructuring of $122 billion is significantly larger than the previous largest U.S. public bankruptcy, which covered approximately $18 billion of debt for the city of Detroit. Puerto Rico’s debt restructuring process and other economic factors or developments, which could occur rapidly, may significantly affect the value of municipal securities of Puerto Rico. In September 2017, the Commonwealth of Puerto Rico did experience severe damage from Hurricane Maria which has impacted the island’s economy and has delayed the resolution of the debt restructuring as timetables are being revised as we begin 2018. The Fund’s vulnerability to potential losses associated with such developments may be reduced through investing in municipal securities that feature credit enhancements (such as bond insurance). The bond insurance provider pays both principal and interest when due to the bond holder. The magnitude of Puerto Rico’s debt restructuring or other adverse economic developments could pose significant strains on the ability of municipal securities insurers to meet all future claims. As of November 30, 2017, 96% of the Puerto Rico municipal securities held by the Fund were insured and all bonds continue to pay full principal and interest.

(M)  Indemnifications.  Under the Fund’s organizational documents, its officers and trustees are indemnified against certain liabilities that may arise out of performance of their duties to the Fund. Additionally, in the normal course of business, the Fund enters into contracts with third-party service providers that contain a variety of representations and warranties and which may provide general indemnifications. The Fund’s maximum exposure under these arrangements is unknown, as this would involve future claims that may be made against the Fund that have not yet occurred. Based on experience, management is of the view that the risk of loss in connection with these potential indemnification obligations is remote. However, there can be no assurance that material liabilities related to such obligations will not arise in the future, which could adversely impact the Fund.

(N)  Quantitative Disclosure of Derivative Holdings.  The following tables show additional disclosures related to the Fund’s derivative and hedging activities, including how such activities are accounted for and their effect on the Fund’s financial positions, performance and cash flows. The Fund entered into United States Treasury Bond futures contracts to help manage the duration and yield curve positioning of the portfolio. These derivatives are not accounted for as hedging instruments.

Fair value of derivative instruments as of November 30, 2017:

Asset Derivatives

	Statement of Assets and Liabilities Location	Interest Rate Contracts Risk		Total
Futures Contracts	Net Assets—Net unrealized appreciation on investments and future contracts (a)	$	672,253	$	672,253
Total Fair Value		$	672,253	$	672,253

(a) Includes cumulative appreciation (depreciation) of futures contracts as reported in the Portfolio of Investments. Only current day’s variation margin is reported within the Statement of Assets and Liabilities.

The effect of derivative instruments on the Statement of Operations for the six-month period ended November 30, 2017:

Realized Gain (Loss)

	Statement of Operations Location	Interest Rate Contracts Risk		Total
Futures Contracts	Net realized gain (loss) on futures transactions	$	311,541	$	311,541
Total Realized Gain (Loss)		$	311,541	$	311,541

26 MainStay DefinedTerm Municipal Opportunities Fund

Change in Unrealized Appreciation (Depreciation)

	Statement of Operations Location	Interest Rate Contracts Risk		Total
Futures Contracts	Net change in unrealized appreciation (depreciation) on futures contracts	$	1,395,046	$	1,395,046
Total Change in Unrealized Appreciation (Depreciation)		$	1,395,046	$	1,395,046

Average Notional Amount

	Interest Rate Contracts Risk			Total
Futures Contracts Short	$	(125,868,516	)	$	(125,868,516	)

Note 3–Fees and Related Party Transactions

(A)  Manager and Subadvisor.  New York Life Investments, a registered investment adviser and an indirect, wholly-owned subsidiary of New York Life Insurance Company (“New York Life”), serves as the Fund’s Manager, pursuant to an Amended and Restated Management Agreement (“Management Agreement”). The Manager provides offices, conducts clerical, recordkeeping and bookkeeping services, and keeps most of the financial and accounting records required to be maintained by the Fund. Except for the portion of salaries and expenses that are the responsibility of the Fund, the Manager pays the salaries and expenses of all personnel affiliated with the Fund and certain operational expenses of the Fund. The Fund reimburses New York Life Investments in an amount equal to a portion of the compensation of the Chief Compliance Officer attributable to the Fund. MacKay Shields LLC (“MacKay Shields” or the “Subadvisor”), a registered investment adviser and an indirect, wholly-owned subsidiary of New York Life, serves as Subadvisor to the Fund and is responsible for the day-to-day portfolio management of the Fund. Pursuant to the terms of a Subadvisory Agreement (“Subadvisory Agreement”) between New York Life Investments and MacKay Shields, New York Life Investments pays for the services of the Subadvisor.

Under the Management Agreement, the Fund pays the Manager a monthly fee for services performed and the facilities furnished at an annual rate of 0.60% of the “Managed Assets”. Managed Assets is defined as the Fund’s total assets, minus the sum of its accrued liabilities (other than Fund liabilities incurred for the purpose of creating effective leverage (i.e. tender option bonds) or Fund liabilities related to liquidation preference of any Preferred shares issued).

During the six-month period ended November 30, 2017, New York Life Investments earned fees from the Fund in the amount of $2,599,095.

State Street provides sub-administration and sub-accounting services to the Fund pursuant to an agreement with New York Life Investments. These services include calculating the daily NAV of the Fund, maintaining the general ledger and sub-ledger accounts for the

calculation of the Fund’s NAV, and assisting New York Life Investments in conducting various aspects of the Fund’s administrative operations. For providing these services to the Fund, State Street is compensated by New York Life Investments.

Effective December 22, 2017, pursuant to an agreement between the Fund and New York Life Investments, New York Life Investments is responsible for providing or procuring certain regulatory reporting services for the Fund. The Fund will reimburse New York Life Investments for the actual costs incurred by New York Life Investments in connection with providing or procuring these services for the Fund.

(B) Transfer, Dividend Disbursing and Shareholder Servicing Agent. Computershare Trust Company, N.A. (“Computershare”), 250 Royall Street, Canton, Massachusetts, 02021, is the Fund’s transfer, dividend disbursing and shareholder servicing agent pursuant to an agreement between the Fund and Computershare.

Note 4–Federal Income Tax

As of November 30, 2017, the cost and unrealized appreciation (depreciation) of the Fund’s investment portfolio, including applicable derivative contracts and other financial instruments, as determined on a federal income tax basis, were as follows:

	Federal Tax Cost		Gross Unrealized Appreciation		Gross Unrealized Depreciation			Net Unrealized Appreciation/ (Depreciation)
Investments in Securities	$	536,394,609	$	58,812,825	$	(9,283,725	)	$	49,529,100

The tax character of distributions paid during the year ended May 31, 2017 to Common shareholders (as reflected in the Statement of Changes in Net Assets) and Preferred shareholders (included as interest expense for financial statement purposes (See Note 2(J)) were as follows:

	2017
Distributions paid from:	Ordinary Income		Exempt Interest Dividends		Long-Term Capital Gain
Common shares	$	526,625	$	29,452,740	$	—
Preferred shares		21,131		1,372,265		—
Total	$	547,756	$	30,825,005	$	—

Note 5–Custodian

State Street is the custodian of cash and securities held by the Fund. Custodial fees are charged to the Fund based on the Fund’s net assets and/or the market value of securities held by the Fund and the number of certain transactions incurred by the Fund.

Note 6–Purchases and Sales of Securities (in 000’s)

During the six-month period ended November 30, 2017, purchases and sales of securities, other than short-term securities, were $54,083 and $59,352, respectively.

27

Notes to Financial Statements (Unaudited) (continued)

Note 7–Capital Share Transactions

Common Shares:	Shares		Amount
Six-month period ended November 30, 2017:
Common shares issued to shareholders in reinvestment of dividends (a)		7,547	$	151,997
Net increase in Common shares outstanding		7,547	$	151,997
Preferred Shares (b):	Shares		Amount
For the period June 26, 2012 through May 31, 2013:
Series A Shares Issued		350	$	35,000,000
Series B Shares Issued		350	$	35,000,000

(a) See page 29 for information on the Fund’s dividend reinvestment plan.

(b) For the period June 1, 2013 through November 30, 2017, there were no new shares issued.

Note 8–Subsequent Events

In connection with the preparation of the financial statements of the Fund as of and for the six-month period ended November 30, 2017, events and transactions subsequent to November 30, 2017, through the date the financial statements were issued have been evaluated by the

Fund’s management for possible adjustment and/or disclosure. No subsequent events requiring financial statement adjustment or disclosure have been identified, other than the following:

On October 2, 2017, the Fund declared a dividend in the amount of $0.09 per Common share, payable on December 29, 2017, to shareholders of record on December 15, 2017.

On December 15, 2017, the Fund paid its semiannual distribution to Series A and Series B Preferred shareholders in the amounts of $1,083 and $959, per Preferred share, respectively.

On January 2, 2018, the Fund declared dividends to Common shareholders for the upcoming quarter as shown in the following schedule:

Month	Ex-Date		Record Date		Payable Date		Amount
January		1/12/2018		1/16/2018		1/31/2018	$	0.09
February		2/14/2018		2/15/2018		2/28/2018	$	0.09
March		3/14/2018		3/15/2018		3/29/2018	$	0.09

At meetings held on December 11-13, 2017, the Board approved a name change for the Fund from MainStay DefinedTerm Municipal Opportunities Fund to MainStay MacKay DefinedTerm Municipal Opportunities Fund, which will take effect on February 28, 2018.

28 MainStay DefinedTerm Municipal Opportunities Fund

Dividend Reinvestment Plan(Unaudited)

Pursuant to the Fund’s Dividend Reinvestment Plan (the “Plan”) shareholders whose shares are registered in their own name may “opt-in” to the Plan and elect to reinvest all or a portion of their distributions in the Common shares by providing the required enrollment notice to Computershare Trust Company, N.A., the Plan Administrator (“Plan Administrator”). Shareholders whose shares are held in the name of a broker or other nominee may have distributions reinvested only if such a service is provided by the broker or the nominee or if the broker or the nominee permits participation in the Plan. Shareholders whose shares are held in the name of a broker or other nominee should contact the broker or nominee for details. A shareholder may terminate participation in the Plan at any time by notifying the Plan Administrator before the record date of the next distribution through the Internet, by telephone or in writing. All distributions to shareholders who do not participate in the Plan, or have elected to terminate their participation in the Plan, will be paid by check mailed directly to the record holder by or under the direction of the Plan Administrator when the Fund declares a distribution.

When the Fund declares a dividend or other distribution (together, a “Dividend”) payable in cash, non-participants in the Plan will receive cash and participants in the Plan (i.e., those holders of Common shares who (“opt-in”) will receive the equivalent in Common shares. The Common shares will be acquired by the Plan Administrator for the participants’ accounts, depending upon the circumstances described below, either (i) through receipt of additional unissued but authorized Common shares from the Fund (“Newly Issued Common Shares”) or (ii) by purchase of outstanding Common shares on the open market (“Open-Market Purchases”) on the NYSE or elsewhere. If, on the payment date for any Dividend, the closing market price per Common share plus estimated per share fees, which include any brokerage commissions the Plan Administrator is required to pay, is equal to or greater than the NAV per Common share, the Plan Administrator will invest the Dividend amount in Newly Issued Common shares on behalf of the participants. The number of Newly Issued Common Shares to be credited to each participant’s account will be determined by dividing the dollar amount of the Dividend by the NAV per Common share on the payment date; provided that, if the NAV is less or equal to 95% of the closing market value on the payment date, the dollar amount of the Dividend will be divided by 95% of the closing market price per Common share on the payment date. If, on the payment date for any Dividend, the NAV per Common share is greater than the closing market value plus estimated per share fees, the Plan Administrator will invest the Dividend amount in Common shares acquired on behalf of the participants in Open-Market Purchases. In the event of a market discount on the payment date for any Dividend, the Plan Administrator will have until the last business day before the next date on which the Common shares trade on an “ex-dividend” basis or 30 days after the payment date for such Dividend, whichever is sooner (the “Last Purchase Date”), to invest the Dividend amount in Common shares acquired in Open-Market Purchases. It is contemplated that the Fund will pay monthly income Dividends. Therefore, the period during which Open-Market Purchases can be made will exist only from the payment date of each Dividend through the date before the next “ex-dividend” date which typically will be approximately ten days. If, before the Plan Administrator has completed its Open-Market Purchases, the market price per Common share exceeds the NAV per Common shares, the average per Common share purchase price paid by the Plan

Administrator may exceed the NAV of the Common shares, resulting in the acquisition of fewer Common shares than if the Dividend had been paid in Newly Issued Common Shares on the Dividend payment date. Because of the foregoing difficulty with respect to Open-Market Purchases, the Plan provides that if the Plan Administrator is unable to invest the full Dividend amount in Open-Market Purchases during the purchase period or if the market discount shifts to a market premium during the purchase period, the Plan Administrator may cease making Open-Market Purchases and may invest the uninvested portion of the Dividend amount in Newly Issued Common Shares at the NAV per Common share at the close of business on the Last Purchase Date provided that, if the NAV per Common share is less than or equal to 95% of the then current market price per Common share; the dollar amount of the Dividend will be divided by 95% of the market price per Common share on the payment date.

The Plan Administrator maintains all shareholders’ accounts in the Plan and furnishes written confirmation of all transactions in the accounts, including information needed by shareholders for tax records. Common shares In the account of each Plan participant will be held by the Plan Administrator on behalf of the Plan participant, and each shareholder proxy will include those shares purchased or received pursuant to the Plan. The Plan Administrator will forward all proxy solicitation materials to participants and vote proxies for shares held under the Plan in accordance with the instructions of the participants.

In the case of shareholders such as banks, brokers or nominees which hold shares for others who are the beneficial owners, the Plan Administrator will administer the Plan on the basis of the number of Common shares certified from time to time by the record shareholder’s name and held for the account of beneficial owners who participate in the Plan.

There will be no charges with respect to Common shares issued directly by the Fund as a result of dividends or capital gains distributions payable either in Common shares or in cash. The Plan Administrator’s fees for the handling of the reinvestment of dividends and distributions will be paid by the Fund. However, each participant will pay a per share fee incurred in connection with Open-Market Purchases. The reinvestment of Dividends will not relieve participants of any Federal, state or local income tax that may be payable (or required to be withheld) on such dividends. See “U.S. Federal Income Tax Matters.” Participants that request a sale of shares through the Plan Administrator are subject to a $2.50 sales fee and a $.15 per share sold fee. All per share fees include any brokerage commission the Plan Administrator is required to pay.

The Fund reserves the right to amend or terminate the Plan. There is no direct service charge to participants with regard to purchases in the Plan; however, the Fund reserves the right to amend the Plan to include a service charge payable by the participants.

All correspondence or questions concerning the Plan should be directed to the Plan Administrator, Computershare Trust Company, N.A., by telephone (855) 456-9683, through the internet at www.computershare.com/investor or in writing to P.O. Box 505000, Louisville, Kentucky 40233.

29

Proxy Results (Unaudited)

The Annual Meeting of Shareholders was held on September 27, 2017, to elect two Class II Trustees for the Fund by shareholders of record as of July 3, 2017. Listed below are the results of this voting.

	Votes For		Votes Against		Abstentions		Total
Alan R. Latshaw		23,039,633		224,591		0		23,264,224
	Votes For		Votes Against		Abstentions		Total
Richard H. Nolan Jr.*		700		0		0		700

*    The holders of Common Shares did not vote for this nominee.

Both Trustees were elected.

On December 31, 2017, Peter Meenan retired from the Board.

These recent changes bring the Fund’s Board size to currently seven Trustees, six of whom are independent.

Proxy Voting Policies and Procedures and Proxy Voting Record

A description of the policies and procedures that New York Life Investments uses to vote proxies related to the Fund’s securities is available without charge, upon request, (i) by visiting the Fund’s website at mainstayinvestments.com; or (ii) on the Securities and Exchange Commission’s (“SEC”) website at www.sec.gov.

The Fund is required to file with the SEC its proxy voting record for the 12-month period ending June 30 on Form N-PX. The Fund’s most recent Form N-PX or proxy voting record is available free of charge upon request (i) by calling 800-MAINSTAY (624-6782); (ii) by visiting the Fund’s website at mainstayinvestments.com; or (iii) on the SEC’s website at www.sec.gov.

Shareholder Reports and Quarterly Portfolio Disclosure

The Fund is required to file its complete schedule of portfolio holdings with the SEC for its first and third fiscal quarters on Form N-Q. The Fund’s Form N-Q is available without charge on the SEC’s website at www.sec.gov or by calling MainStay Investments at 800-MAINSTAY (624-6782). You also can obtain and review copies of Form N-Q by visiting the SEC’s Public Reference Room in Washington, DC (information on the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330).

30 MainStay DefinedTerm Municipal Opportunities Fund

This page intentionally left blank

Manager

New York Life Investment Management LLC

New York, New York

Subadvisor

MacKay Shields LLC¹

New York, New York

Legal Counsel

Dechert LLP

Independent Registered Public Accounting Firm

PricewaterhouseCoopers LLP

Transfer, Dividend Disbursing and Shareholder Servicing Agent

Computershare Trust Company, N.A.

P.O. Box 505000

Louisville, Kentucky 40233

(855) 456-9683

mainstayinvestments.com/mmd

1. An affiliate of New York Life Investment Management LLC.

MainStay Investments^® is a registered service mark and name under which New York Life Investment Management LLC does business. MainStay Investments, an indirect subsidiary of New York Life Insurance Company, New York, NY 10010, provides investment advisory products and services.

Not FDIC/NCUA Insured Not a Deposit May Lose Value No Bank Guarantee Not Insured by Any Government Agency

1722074 MS347-17 MSMHI10-01/18
(NYLIM) NL264

Item 2. Code of Ethics.

Not applicable.

Item 3. Audit Committee Financial Expert.

Not applicable.

Item 4. Principal Accountant Fees and Services.

Not applicable.

Item 5. Audit Committee of Listed Registrants

Not applicable.

Item 6. Schedule of Investments

The Schedule of Investments is included as part of Item 1 of this report.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies.

Not applicable.

Item 8. Portfolio Managers of Closed-End Management Investment Companies.

Not applicable.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

Not applicable.

Item 10. Submission of Matters to a Vote of Security Holders.

There have been no material changes to the procedures by which shareholders may recommend nominees to the Registrant’s Board of Trustees.

Item 11. Controls and Procedures.

(a) Based on an evaluation of the Registrant’s Disclosure Controls and Procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) (the “Disclosure Controls”), as of a date within 90 days prior to the filing date (the “Filing Date”) of this Form N-CSR (the “Report”), the Registrant’s principal executive officer and principal financial officer have concluded that the Disclosure Controls are reasonably designed to ensure that information required to be disclosed by the Registrant in the Report is recorded, processed, summarized and reported by the Filing Date, including ensuring that information required to be disclosed in the Report is accumulated and communicated to the Registrant’s management,

including the Registrant’s principal executive officer and principal financial officer, as appropriate to allow timely decisions regarding required disclosure.

(b) There were no changes in the Registrant’s internal control over financial reporting (as defined in Rule 30a-3(d)) under the Investment Company Act of 1940 that occurred during the second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the Registrant’s internal control over financial reporting.

Item 12. Exhibits.

(a) Certifications of principal executive officer and principal financial officer as required by Rule 30a-2 under the Investment Company Act of 1940.

(b) Certifications of principal executive officer and principal financial officer as required by Section 906 of the Sarbanes-Oxley Act of 2002.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the Registrant has duly caused this Report to be signed on its behalf by the undersigned, thereunto duly authorized.

MAINSTAY DEFINEDTERM MUNICIPAL OPPORTUNITIES FUND

By:	/s/ Kirk C. Lehneis
	Kirk C. Lehneis
	President and Principal Executive Officer

Date: February 7, 2018

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this Report has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated.

By:	/s/ Kirk C. Lehneis
	Kirk C. Lehneis
	President and Principal Executive Officer

Date: February 7, 2018

By:	/s/ Jack R. Benintende
	Jack R. Benintende
	Treasurer and Principal Financial and Accounting Officer

Date: February 7, 2018

EXHIBIT INDEX

(a)(2) Certifications of principal executive officer and principal financial officer as required by Rule 30a-2 under the Investment Company Act of 1940.

(b)      Certification of principal executive officer and principal financial officer as required by Section 906 of the Sarbanes-Oxley Act of 2002.