MainStay Candriam Emerging Markets Debt Fund

Message from the President and Semiannual Report

Unaudited  |  April 30, 2023

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Message from the 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
Investment and Performance Comparison	5
Portfolio Management Discussion and Analysis	9
Portfolio of Investments	12
Financial Statements	19
Notes to Financial Statements	25
Board Consideration and Approval of Management Agreement and Subadvisory Agreement	36
Discussion of the Operation and Effectiveness of the Fund's Liquidity Risk Management Program	41
Proxy Voting Policies and Procedures and Proxy Voting Record	42
Shareholder Reports and Quarterly Portfolio Disclosure	42

Investors should refer to the Fund’s Summary Prospectus and/or Prospectus and consider the Fund’s investment objectives, strategies, risks, charges and expenses carefully before investing. The Summary Prospectus and/or Prospectus contain this and other information about the Fund. You may obtain copies of the Fund’s Summary Prospectus, Prospectus and Statement of Additional Information, which includes information about The MainStay Funds' Trustees, free of charge, upon request, by calling toll-free 800-624-6782, by writing to NYLIFE Distributors LLC, Attn: MainStay Marketing Department, 30 Hudson Street, Jersey City, NJ 07302 or by sending an e-mail to MainStayShareholderServices@nylim.com. These documents are also available via the MainStay Funds’ website at newyorklifeinvestments.com. Please read the Fund’s Summary Prospectus and/or Prospectus carefully before investing.

Investment and Performance Comparison (Unaudited)

Performance data quoted represents past performance. 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. The graph below depicts the historical performance of Class I shares of the Fund. Performance will vary from class to class based on differences in class-specific expenses and sales charges. For performance information current to the most recent month-end, please call 800-624-6782 or visit newyorklifeinvestments.com.

The performance table and graph do not reflect the deduction of taxes that a shareholder would pay on distributions or Fund share redemptions. Total returns reflect maximum applicable sales charges as indicated in the table below, if any, changes in share price, and reinvestment of dividend and capital gain distributions. The graph assumes the initial investment amount shown below and reflects the deduction of all sales charges that would have applied for the period of investment. Performance figures may reflect certain fee waivers and/or expense limitations, without which total returns may have been lower. For more information on share classes and current fee waivers and/or expense limitations (if any), please refer to the Notes to Financial Statements.

Average Annual Total Returns for the Period-Ended April 30, 2023
Class	Sales Charge		Inception Date1	Six Months2	One Year	Five Years	Ten Years	Gross Expense Ratio3
Class A Shares	Maximum 4.50% Initial Sales Charge	With sales charges	6/1/1998	4.86%	-7.85%	-2.63%	-0.30%	1.36%
		Excluding sales charges		9.80	-3.51	-1.73	0.16	1.36
Investor Class Shares4	Maximum 4.00% Initial Sales Charge	With sales charges	2/28/2008	5.18	-7.75	-2.95	-0.56	1.78
		Excluding sales charges		9.57	-3.91	-2.05	-0.10	1.78
Class B Shares5	Maximum 5.00% CDSC	With sales charges	6/1/1998	4.21	-9.16	-3.12	-0.85	2.52
	if Redeemed Within the First Six Years of Purchase	Excluding sales charges		9.21	-4.63	-2.80	-0.85	2.52
Class C Shares	Maximum 1.00% CDSC	With sales charges	9/1/1998	8.20	-5.53	-2.80	-0.85	2.52
	if Redeemed Within One Year of Purchase	Excluding sales charges		9.20	-4.63	-2.80	-0.85	2.52
Class I Shares	No Sales Charge		8/31/2007	9.95	-3.22	-1.44	0.43	1.12

    

1.	Prior to February 28, 2017, the Fund's primary investment strategies were changed. Effective June 21, 2019, the Fund replaced its prior subadvisor and modified its investment objective and principal investment strategies. The performance in the graph and table prior to those dates reflects its prior subadvisor's, investment objective and principal investment strategies.
2.	Not annualized.
3.	The gross expense ratios presented reflect the Fund’s “Total Annual Fund Operating Expenses” from the most recent Prospectus, as supplemented, and may differ from other expense ratios disclosed in this report.
4.	Prior to June 30, 2020, the maximum initial sales charge was 4.50%, which is reflected in the applicable average annual total return figures shown.
5.	Class B shares are closed to all new purchases as well as additional investments by existing Class B shareholders.

The footnotes on the next page are an integral part of the table and graph and should be carefully read in conjunction with them.

5

Benchmark Performance*	Six Months1	One Year	Five Years	Ten Years
JPMorgan EMBI Global Diversified Index2	10.54%	-0.89%	-0.20%	1.77%
Morningstar Emerging Markets Bond Category Average3	10.91	-0.40	-0.39	0.85

    

*	Returns for indices reflect no deductions for fees, expenses or taxes, except for foreign withholding taxes where applicable. Results assume reinvestment of all dividends and capital gains. An investment cannot be made directly in an index.
1.	Not annualized.
2.	The JPMorgan EMBI Global Diversified Index is the Fund’s primary broad-based securities market index for comparison purposes. The JPMorgan EMBI Global Diversified Index is a market-capitalization weighted, total return index tracking the traded market for U.S. dollar-denominated Brady Bonds, Eurobonds, traded loans and local market debt instruments issued by sovereign and quasi-sovereign entities.
3.	The Morningstar Emerging Markets Bond Category Average is representative of funds that invest more than 65% of their assets in foreign bonds from developing countries. The largest portion of the emerging-markets bond market comes from Latin America, followed by Eastern Europe. Africa, the Middle East, and Asia make up the rest. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.

The footnotes on the preceding page are an integral part of the table and graph and should be carefully read in conjunction with them.

6	MainStay Candriam Emerging Markets Debt Fund

Cost in Dollars of a $1,000 Investment in MainStay Candriam Emerging Markets Debt Fund (Unaudited)

The example below is intended to describe the fees and expenses borne by shareholders during the six-month period from November 1, 2022 to April 30, 2023, and the impact of those costs on your investment.

Example

As a shareholder of the Fund you incur two types of costs: (1) transaction costs, including exchange fees and sales charges (loads) on purchases (as applicable), and (2) ongoing costs, including management fees, distribution and/or service (12b-1) fees and other Fund expenses (as applicable). This example is intended to help you understand your ongoing costs (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 made at the beginning of the six-month period and held for the entire period from November 1, 2022 to April 30, 2023.

This example illustrates your Fund’s ongoing costs in two ways:

Actual Expenses

The second and third data columns in the table below provide information about actual account values and actual expenses. You may use the information in these columns, together with the amount you invested, to estimate the expenses that you paid during the six months ended April 30, 2023. Simply divide your account value by $1,000 (for example, an

$8,600 account value divided by $1,000 = 8.6), then multiply the result by the number under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The fourth and fifth data columns in the table below provide information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balances or expenses you paid for the six-month period shown. You may use this information to compare the ongoing costs of investing in the Fund with the ongoing costs of investing in other mutual funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other mutual funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as exchange fees or sales charges (loads). Therefore, the fourth and fifth data columns of the table are useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

7

Country Composition as of April 30, 2023 (Unaudited)

Mexico	7.5%
Colombia	5.8
Saudi Arabia	5.3
Romania	5.2
Panama	5.0
Hungary	4.8
Dominican Republic	4.4
Brazil	3.8
United States	3.6
Indonesia	3.1
Argentina	2.9
Peru	2.8
South Africa	2.8
Poland	2.6
Nigeria	2.4
Senegal	2.4
Cote D'Ivoire	2.2
Chile	2.2
Azerbaijan	2.1
Ghana	1.8
Sri Lanka	1.3
Croatia	1.3
Zambia	1.3
Angola	1.3

Ukraine	1.2%
Venezuela	1.1
Morocco	1.1
Tunisia	1.0
Oman	1.0
Montenegro	1.0
Jordan	1.0
Republic of the Congo	0.9
Iraq	0.9
United Arab Emirates	0.8
Cameroon	0.8
Georgia	0.8
Republic Of Serbia	0.8
Bahrain	0.8
Papua New Guinea	0.8
Philippines	0.7
Ecuador	0.6
Gabon	0.5
Republic of North Macedonia	0.3
Tajikistan	0.3
Lebanon	0.2
Other Assets, Less Liabilities	5.5
	100.0%

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8	MainStay Candriam Emerging Markets Debt Fund

Portfolio Management Discussion and Analysis (Unaudited)

Questions answered by portfolio managers Diliana Deltcheva, CFA, Christopher Mey, CFA, and Richard Briggs, CFA, of Candriam, the Fund’s Subadvisor.

9

duration position contributed marginally to the performance of the Fund.

How was the Fund affected by shifting currency values during the reporting period?

The Fund was not affected by shifting currency values during the reporting period.

During the reporting period, which countries and/or sectors were the strongest positive contributors to the Fund’s relative performance and which countries and/or sectors were particularly weak?

The Fund’s small position in Venezuela contributed positively to relative performance, especially in the fourth quarter of 2022. Bonds issued by Petróleos de Venezuela (PDVSA), the Venezuelan state-owned oil and natural gas company, remained at prices below ten cents on the dollar, but outperformed after the Biden administration granted Chevron a license to resume oil production in the country. This followed the resumption of talks between the Maduro administration and Venezuela’s opposition in Mexico City. The Fund’s underweight position in Egypt also contributed positively to performance, as risk premiums rose due to an increase in funding uncertainty. Egypt was dependent on privatization revenues to bridge its 2022/23 funding gap but made little progress. The government issued a 3-year sukuk (a sharia-compliant, bond-like product used in Islamic finance) in February, at an unsustainable 10.875% coupon, which only exposed the funding stress and accelerated the correction. In addition, the Fund’s overweight position in Romania paid off as the government managed to issue $6 billion in external debt in the first quarter of 2023, representing 70% of the planned issuance for the year. Minimizing supply risks alongside a relatively well-performing economy amid a general European Union slowdown supported compression of risk premiums.

Conversely, the Fund’s overweight position in Argentina detracted from relative performance as the country’s debt corrected materially after the January 2023 rally in the face of elevated, generalized market volatility. We continue to maintain a constructive view on the credit, as we believe the likelihood of an opposition win and a return to orthodox macroeconomic policies is high. In addition, default risks are aggressively priced in by sovereign Eurobonds trading in the low 20s. Overweight exposure to Tunisia also detracted, as the long-awaited IMF Extended Fund Facility of $1.9 billion did not materialize during the reporting period due to controversial domestic politics. We believe a deal will be concluded during the second quarter of 2023, as prior

actions, including the state-owned-enterprise and budget laws were completed by February. In addition, the European Union (the “EU”) strengthened its financial support for Tunisia, which is considered a critical country in the management of EU’s migrant crisis. Finally, Turkey was also a small detractor, mostly as a result of the Fund’s underweight position in the country, which saw a strong rally in the fourth quarter of 2022 based on optimism regarding possible ‘regime change’ in the planned May 2023 general elections.

What were some of the Fund’s largest purchases and sales during the reporting period?

Toward the end of 2022, we cut Fund credits that had rallied too far, including bonds from Gabon, Angola, Buenos Aires, Ukraine, Mozambique, Oman, Bahrain, the Bahamas among others. We trimmed the Fund’s overweight exposure to sub-Saharan Africa during the fourth quarter, with reductions in Gabon, Angola and Mozambique, in particular.

During the first quarter of 2023, we increased the Fund’s overweight exposures to BBB or BB-rated Eastern European and Latin American issuers—including Hungary, Panama, Poland, Romania and Dominican Republic—that offered attractive relative value versus other investment-grade or BB-rated credits.⁴ We also reduced exposure to Ecuador, Egypt, El Salvador and Pakistan, rotating into Angola, Argentina and Nigeria, acknowledging our belief that some frontier issuers are likely to remain under funding stress, while oil exporters and Argentina (where regime change is expected in the October 2023 elections) are likely to fare better.

How did the Fund’s country and/or sector weightings change during the reporting period?

We added to the Fund’s holdings of Eastern European credits from countries such as Hungary, Poland, and Romania via primary markets in the first quarter of 2023. We also added to the Fund’s positions in Costa Rica and North Macedonia via attractively priced new deals.

We fully exited the Fund’s positions in Egypt, El Salvador and Pakistan as we assessed that these countries might be forced into debt restructuring at some point over the next year. We reduced exposure to Ecuador after the country’s failed constitutional referendum, which materially challenged Ecuador’s governability and increased the prospects of a presidential impeachment. We added to holdings in Argentina based on the view that a Peronist loss during the upcoming October elections will usher in

10	MainStay Candriam Emerging Markets Debt Fund

long-awaited, orthodox macro-economic management and lead to a decline of restructuring risks.

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

As of April 30, 2023, the Fund holds underweight energy exposure via investment-grade-rated credits, with overweight exposure in Azerbaijan, Iraq, Nigeria, The Republic of the Congo and Venezuela and PDVSA; neutral exposure in Angola; and underweight exposure in Bahrain, Ecuador, Kazakhstan, Malaysia, Qatar, Oman, Saudi Arabia and The United Arab Emirates (the “UAE”).

The Fund maintains exposure to select idiosyncratic, high-yield-rated credits from countries including Argentina (and the Buenos Aires Province), Ghana, Cameroon, Mozambique, Papua New Guinea, Tunisia, Ukraine and Zambia. However, the Fund holds underweight exposure to high-yield credits from Turkey, The Commonwealth of Independent States (Uzbekistan, Tajikistan), Bolivia, Honduras, Jamaica and frontier credits such as Bolivia, El Salvador, Ethiopia, Kenya, Mongolia, Pakistan and Suriname.

The Fund maintains underweight positions in rich, investment-grade-rated credits from countries including China, Peru, the Philippines, Saudi Arabia, Qatar, the UAE and Uruguay, but holds overweight positions in attractively valued credits rated BBB from countries such as Hungary, Indonesia, Mexico, Panama and Romania.

The Fund generally maintains underweight exposure to the most expensive investment-grade credits, as well as in the BB space, given that they trade tight, both within an emerging-markets context and versus developed-markets corporate credit, making them particularly unattractive.

The Fund continues to hold no Turkish exposure, given the country’s deeply negative net foreign-exchange reserves, which are only being supported by large deposits from Gulf Cooperation Council central banks, and which could potentially prove unsustainable. The Fund holds no exposure to Belarus, Kazakhstan, Russia, Uzbekistan and Tajikistan on elevated governance, default and sanctions risks that, in our opinion, are not sufficiently compensated by valuations. 

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.

11

Portfolio of Investments April 30, 2023^{†^}(Unaudited)

	Principal Amount	Value
Foreign Government Bonds (continued)
Cameroon 0.8%
Cameroon Government Bond
Series Reg S
5.95%, due 7/7/32	EUR    425,000	$    326,982
Series Reg S
9.50%, due 11/19/25	$    200,000	191,288
		518,270
Chile 2.2%
Chile Government Bond
3.10%, due 1/22/61	300,000	200,334
3.25%, due 9/21/71	600,000	399,106
3.50%, due 4/15/53 (e)	550,000	417,893
Corp. Nacional del Cobre de Chile
Series Reg S
5.125%, due 2/2/33	350,000	354,305
		1,371,638
Colombia 5.8%
Colombia Government Bond
4.50%, due 1/28/26	500,000	474,889
5.00%, due 6/15/45	300,000	201,254
5.20%, due 5/15/49	300,000	201,773
6.125%, due 1/18/41	500,000	395,011
7.50%, due 2/2/34	500,000	478,976
8.00%, due 4/20/33 (e)	987,000	984,338
Ecopetrol SA
4.625%, due 11/2/31	700,000	525,080
8.875%, due 1/13/33	300,000	290,868
		3,552,189
Cote D'Ivoire 2.2%
Ivory Coast Government Bond
Series Reg S
4.875%, due 1/30/32	EUR  1,000,000	832,776
Series Reg S
5.75%, due 12/31/32 (d)	$  596,945	549,190
		1,381,966
Croatia 1.3%
Croatia Government Bond
Series Reg S
6.00%, due 1/26/24	800,000	804,374
Dominican Republic 4.4%
Dominican Republic Government Bond
Series Reg S
4.875%, due 9/23/32	300,000	258,297

	Principal Amount	Value
Dominican Republic (continued)
Dominican Republic Government Bond (continued)
Series Reg S
5.50%, due 1/27/25	$     500,000	$    494,771
Series Reg S
5.50%, due 2/22/29	300,000	285,469
Series Reg S
5.875%, due 1/30/60	1,000,000	761,933
Series Reg S
5.95%, due 1/25/27	500,000	495,769
Series Reg S
6.40%, due 6/5/49 (e)	500,000	419,090
		2,715,329
Ecuador 0.6%
Ecuador Government Bond (d)
Series Reg S
1.50%, due 7/31/40	800,000	260,000
Series Reg S
2.50%, due 7/31/35	344,321	125,912
		385,912
Gabon 0.5%
Gabon Government Bond
Series Reg S
7.00%, due 11/24/31	400,000	295,040
Ghana 1.8%
Ghana Government Bond (a)(c)
Series Reg S
7.75%, due 4/7/29	700,000	255,640
Series Reg S
7.875%, due 2/11/35	900,000	332,280
Series Reg S
8.627%, due 6/16/49	1,500,000	525,000
		1,112,920
Hungary 4.8%
Hungary Government Bond
Series Reg S
3.125%, due 9/21/51	1,000,000	618,014
Series Reg S
5.00%, due 2/22/27	EUR  700,000	782,437
Series Reg S
6.25%, due 9/22/32	$  800,000	829,000
7.625%, due 3/29/41	300,000	340,815

Portfolio of Investments April 30, 2023^{†^}(Unaudited) (continued)

	Principal Amount	Value
Foreign Government Bonds (continued)
Peru (continued)
Peru Government Bond (continued)
3.60%, due 1/15/72	$     400,000	$    274,403
6.55%, due 3/14/37	500,000	556,372
		1,195,796
Philippines 0.7%
Philippine Government Bond
4.20%, due 3/29/47	500,000	437,523
Poland 2.6%
Poland Government Bond
Series Reg S
3.875%, due 2/14/33	EUR  800,000	869,931
Series Reg S
4.25%, due 2/14/43	500,000	532,444
5.50%, due 4/4/53	$  175,000	181,151
		1,583,526
Republic of North Macedonia 0.3%
North Macedonia Government Bond
Series Reg S
6.96%, due 3/13/27	EUR  183,000	204,168
Republic Of Serbia 0.8%
Serbia Government Bond
Series Reg S
6.25%, due 5/26/28	$  200,000	204,040
Series Reg S
6.50%, due 9/26/33	300,000	304,141
		508,181
Republic of the Congo 0.9%
Congo Government Bond
Series Reg S
6.00%, due 6/30/29 (d)	669,750	567,345
Romania 5.2%
Romanian Government Bond
Series Reg S
3.00%, due 2/14/31	300,000	250,230
Series Reg S
5.125%, due 6/15/48	900,000	756,000
Series Reg S
5.25%, due 11/25/27	600,000	593,340

	Principal Amount	Value
Romania (continued)
Romanian Government Bond (continued)
Series Reg S
6.00%, due 5/25/34	$   1,600,000	$  1,586,432
		3,186,002
Saudi Arabia 0.6%
Saudi Government Bond
Series Reg S
3.45%, due 2/2/61	500,000	358,150
Senegal 2.4%
Senegal Government Bond
Series Reg S
5.375%, due 6/8/37	EUR  1,358,000	947,209
Series Reg S
6.25%, due 5/23/33 (e)	$  642,000	504,021
		1,451,230
South Africa 2.8%
South Africa Government Bond
4.30%, due 10/12/28	500,000	448,385
5.75%, due 9/30/49	250,000	179,044
5.875%, due 4/20/32	800,000	725,600
7.30%, due 4/20/52	450,000	383,141
		1,736,170
Sri Lanka 1.3%
Sri Lanka Government Bond (a)(c)
Series Reg S
6.20%, due 5/11/27	600,000	196,748
Series Reg S
6.825%, due 7/18/26	1,150,000	402,011
Series Reg S
7.55%, due 3/28/30	650,000	213,154
		811,913
Tajikistan 0.3%
Tajiskistan Government Bond
Series Reg S
7.125%, due 9/14/27	202,000	156,085
Tunisia 1.0%
Tunisian Republic
Series Reg S
5.625%, due 2/17/24	EUR  300,000	223,135
Series Reg S
5.75%, due 1/30/25	$  800,000	409,365
		632,500

Portfolio of Investments April 30, 2023^{†^}(Unaudited) (continued)

Foreign Currency Forward Contracts

As of April 30, 2023, the Fund held the following foreign currency forward contracts¹:

Currency Purchased		Currency Sold		Counterparty	Settlement Date	Unrealized Appreciation (Depreciation)2
USD	549,920	EUR	500,000	Barclays Capital	5/17/23	$  (1,552)
USD	1,612,850	EUR	1,500,000	JPMorgan Chase Bank N.A.	5/17/23	(41,565)
USD	3,488,659	EUR	3,200,000	JPMorgan Chase Bank N.A.	5/17/23	(40,759)
Total Unrealized Depreciation						$ (83,876)

    

1.	Foreign Currency Forward Contracts are subject to limitations such that they cannot be “sold or repurchased,” although the Fund would be able to exit the transaction through other means, such as through the execution of an offsetting transaction.
2.	As of April 30, 2023, cash in the amount of $270,000 was on deposit with a broker or forward commission merchant for forward transactions.

Futures Contracts

As of April 30, 2023, the Fund held the following futures contracts¹:

Type	Number of Contracts	Expiration Date	Value at Trade Date	Current Notional Amount	Unrealized Appreciation (Depreciation)2
Long Contracts
U.S. Treasury 5 Year Notes	157	June 2023	$  17,202,192	$  17,229,524	$  27,332
Short Contracts
Euro-Bund	(23)	June 2023	(3,375,221)	(3,435,592)	(60,371)
Net Unrealized Depreciation					$ (33,039)

    

1.	As of April 30, 2023, cash in the amount of $432,387 was on deposit with a broker or futures commission merchant for futures transactions.
2.	Represents the difference between the value of the contracts at the time they were opened and the value as of April 30, 2023.

    

Abbreviation(s):

EUR—Euro

USD—United States Dollar

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

17

Portfolio of Investments April 30, 2023^{†^}(Unaudited) (continued)

The following is a summary of the fair valuations according to the inputs used as of April 30, 2023, for valuing the Fund’s assets and liabilities:

Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Asset Valuation Inputs
Investments in Securities (a)
Long-Term Bonds
Corporate Bonds	$  —		$  6,612,306		$ —		$  6,612,306
Foreign Government Bonds	—		49,428,263		—		49,428,263
Total Long-Term Bonds	—		56,040,569		—		56,040,569
Short-Term Investment
Unaffiliated Investment Company	2,257,042		—		—		2,257,042
Total Investments in Securities	2,257,042		56,040,569		—		58,297,611
Other Financial Instruments
Futures Contracts (b)	27,332		—		—		27,332
Total Investments in Securities and Other Financial Instruments	$  2,284,374		$  56,040,569		$ —		$  58,324,943
Liability Valuation Inputs
Other Financial Instruments (b)
Foreign Currency Forward Contracts	$  —		$  (83,876)		$ —		$  (83,876)
Futures Contracts	(60,371)		—		—		(60,371)
Total Other Financial Instruments	$  (60,371)		$  (83,876)		$ —		$  (144,247)

    

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

18	MainStay Candriam Emerging Markets Debt Fund

Statement of Assets and Liabilities as of April 30, 2023 (Unaudited)

Statement of Operations for the six months ended April 30, 2023 (Unaudited)

Investment Income (Loss)
Income
Interest	$ 2,151,990
Securities lending, net	12,623
Total income	2,164,613
Expenses
Manager (See Note 3)	223,117
Transfer agent (See Note 3)	81,663
Distribution/Service—Class A (See Note 3)	61,475
Distribution/Service—Investor Class (See Note 3)	11,417
Distribution/Service—Class B (See Note 3)	2,035
Distribution/Service—Class C (See Note 3)	6,173
Professional fees	44,095
Registration	39,081
Custodian	19,896
Shareholder communication	1,003
Trustees	807
Miscellaneous	2,794
Total expenses before waiver/reimbursement	493,556
Expense waiver/reimbursement from Manager (See Note 3)	(100,349)
Reimbursement from prior custodian(a)	(127)
Net expenses	393,080
Net investment income (loss)	1,771,533
Realized and Unrealized Gain (Loss)
Net realized gain (loss) on:
Unaffiliated investment transactions	(3,472,572)
Futures transactions	158,689
Foreign currency transactions	43,113
Foreign currency forward transactions	(65,950)
Net realized gain (loss)	(3,336,720)
Net change in unrealized appreciation (depreciation) on:
Unaffiliated investments	7,702,740
Futures contracts	(34,263)
Foreign currency forward contracts	(83,876)
Translation of other assets and liabilities in foreign currencies	14,026
Net change in unrealized appreciation (depreciation)	7,598,627
Net realized and unrealized gain (loss)	4,261,907
Net increase (decrease) in net assets resulting from operations	$ 6,033,440

    

(a)	Represents a refund for overbilling of custody fees.

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

20	MainStay Candriam Emerging Markets Debt Fund

Statements of Changes in Net Assets
for the six months ended April 30, 2023 (Unaudited) and the year ended October 31, 2022

	Six months ended April 30, 2023	Year ended October 31, 2022
Increase (Decrease) in Net Assets
Operations:
Net investment income (loss)	$ 1,771,533	$ 3,647,283
Net realized gain (loss)	(3,336,720)	(13,154,988)
Net change in unrealized appreciation (depreciation)	7,598,627	(13,895,370)
Net increase (decrease) in net assets resulting from operations	6,033,440	(23,403,075)
Distributions to shareholders:
Class A	(1,856,162)	(3,612,534)
Investor Class	(314,037)	(549,300)
Class B	(13,935)	(37,561)
Class C	(42,123)	(107,128)
Class I	(147,972)	(237,169)
	(2,374,229)	(4,543,692)
Distributions to shareholders from return of capital:
Class A	—	(277,063)
Investor Class	—	(42,129)
Class B	—	(2,881)
Class C	—	(8,216)
Class I	—	(18,190)
	—	(348,479)
Total distributions to shareholders	(2,374,229)	(4,892,171)
Capital share transactions:
Net proceeds from sales of shares	10,548,270	12,957,410
Net asset value of shares issued to shareholders in reinvestment of distributions	2,270,893	4,663,688
Cost of shares redeemed	(16,962,984)	(31,448,175)
Increase (decrease) in net assets derived from capital share transactions	(4,143,821)	(13,827,077)
Net increase (decrease) in net assets	(484,610)	(42,122,323)
Net Assets
Beginning of period	62,144,376	104,266,699
End of period	$ 61,659,766	$ 62,144,376

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

21

Financial Highlights selected per share data and ratios

	Six months ended April 30, 2023*		Year Ended October 31,
Class A			2022		2021		2020		2019		2018
Net asset value at beginning of period	$ 6.88		$ 9.73		$ 9.81		$ 10.46		$ 9.71		$ 10.88
Net investment income (loss) (a)	0.20		0.38		0.36		0.47		0.49		0.45
Net realized and unrealized gain (loss)	0.47		(2.73)		0.04		(0.67)		0.76		(1.19)
Total from investment operations	0.67		(2.35)		0.40		(0.20)		1.25		(0.74)
Less distributions:
From net investment income	(0.27)		(0.46)		(0.48)		(0.45)		(0.50)		(0.43)
Return of capital	—		(0.04)		—		—		—		—
Total distributions	(0.27)		(0.50)		(0.48)		(0.45)		(0.50)		(0.43)
Net asset value at end of period	$ 7.28		$ 6.88		$ 9.73		$ 9.81		$ 10.46		$ 9.71
Total investment return (b)	9.80%		(24.93)%		4.00%		(1.80)%		13.05%		(6.95)%
Ratios (to average net assets)/Supplemental Data:
Net investment income (loss)	5.64%††		4.53%		3.58%		4.70%		4.78%		4.36%
Net expenses (c)	1.15%††		1.15%		1.16%		1.17%		1.23%		1.26%
Expenses (before waiver/reimbursement) (c)	1.46%††		1.36%		1.31%		1.33%		1.26%		1.26%
Portfolio turnover rate	80%		116%		112%		102%		102%		44%
Net assets at end of period (in 000’s)	$ 47,546		$ 48,053		$ 81,092		$ 82,874		$ 93,472		$ 86,452

    

*	Unaudited.
††	Annualized.
(a)	Per share data based on average shares outstanding during the period.
(b)	Total investment return is calculated exclusive of sales charges and assumes the reinvestment of dividends and distributions. For periods of less than one year, total return is not annualized.
(c)	In addition to the fees and expenses which the Fund bears directly, it also indirectly bears a pro-rata share of the fees and expenses of the underlying funds in which it invests. Such indirect expenses are not included in the above expense ratios.

    

	Six months ended April 30, 2023*		Year Ended October 31,
Investor Class			2022		2021		2020		2019		2018
Net asset value at beginning of period	$ 6.96		$ 9.84		$ 9.91		$ 10.57		$ 9.80		$ 10.98
Net investment income (loss) (a)	0.19		0.35		0.33		0.44		0.47		0.43
Net realized and unrealized gain (loss)	0.47		(2.77)		0.04		(0.68)		0.77		(1.20)
Total from investment operations	0.66		(2.42)		0.37		(0.24)		1.24		(0.77)
Less distributions:
From net investment income	(0.25)		(0.43)		(0.44)		(0.42)		(0.47)		(0.41)
Return of capital	—		(0.03)		—		—		—		—
Total distributions	(0.25)		(0.46)		(0.44)		(0.42)		(0.47)		(0.41)
Net asset value at end of period	$ 7.37		$ 6.96		$ 9.84		$ 9.91		$ 10.57		$ 9.80
Total investment return (b)	9.57%		(25.27)%		3.70%		(2.20)%		12.82%		(7.18)%
Ratios (to average net assets)/Supplemental Data:
Net investment income (loss)	5.16%††		4.14%		3.21%		4.38%		4.50%		4.15%
Net expenses (c)	1.64%††		1.56%		1.53%		1.49%		1.52%		1.47%
Expenses (before waiver/reimbursement) (c)	1.97%††		1.78%		1.70%		1.66%		1.56%		1.49%
Portfolio turnover rate	80%		116%		112%		102%		102%		44%
Net assets at end of period (in 000's)	$ 9,015		$ 8,670		$ 12,806		$ 13,801		$ 16,024		$ 15,911

    

*	Unaudited.
††	Annualized.
(a)	Per share data based on average shares outstanding during the period.
(b)	Total investment return is calculated exclusive of sales charges and assumes the reinvestment of dividends and distributions. For periods of less than one year, total return is not annualized.
(c)	In addition to the fees and expenses which the Fund bears directly, it also indirectly bears a pro-rata share of the fees and expenses of the underlying funds in which it invests. Such indirect expenses are not included in the above expense ratios.

    

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

22	MainStay Candriam Emerging Markets Debt Fund

Financial Highlights selected per share data and ratios

	Six months ended April 30, 2023*		Year Ended October 31,
Class B			2022		2021		2020		2019		2018
Net asset value at beginning of period	$ 6.72		$ 9.52		$ 9.61		$ 10.26		$ 9.52		$ 10.69
Net investment income (loss) (a)	0.16		0.27		0.24		0.36		0.38		0.34
Net realized and unrealized gain (loss)	0.46		(2.67)		0.04		(0.66)		0.75		(1.18)
Total from investment operations	0.62		(2.40)		0.28		(0.30)		1.13		(0.84)
Less distributions:
From net investment income	(0.23)		(0.37)		(0.37)		(0.35)		(0.39)		(0.33)
Return of capital	—		(0.03)		—		—		—		—
Total distributions	(0.23)		(0.40)		(0.37)		(0.35)		(0.39)		(0.33)
Net asset value at end of period	$ 7.11		$ 6.72		$ 9.52		$ 9.61		$ 10.26		$ 9.52
Total investment return (b)	9.21%		(25.85)%		2.87%		(2.91)%		12.04%		(7.98)%
Ratios (to average net assets)/Supplemental Data:
Net investment income (loss)	4.40%††		3.31%		2.49%		3.66%		3.76%		3.37%
Net expenses (c)	2.39%††		2.31%		2.28%		2.24%		2.27%		2.22%
Expenses (before waiver/reimbursement) (c)	2.72%††		2.52%		2.45%		2.40%		2.31%		2.24%
Portfolio turnover rate	80%		116%		112%		102%		102%		44%
Net assets at end of period (in 000’s)	$ 367		$ 426		$ 1,129		$ 1,789		$ 2,663		$ 3,660

    

*	Unaudited.
††	Annualized.
(a)	Per share data based on average shares outstanding during the period.
(b)	Total investment return is calculated exclusive of sales charges and assumes the reinvestment of dividends and distributions. For periods of less than one year, total return is not annualized.
(c)	In addition to the fees and expenses which the Fund bears directly, it also indirectly bears a pro-rata share of the fees and expenses of the underlying funds in which it invests. Such indirect expenses are not included in the above expense ratios.

    

	Six months ended April 30, 2023*		Year Ended October 31,
Class C			2022		2021		2020		2019		2018
Net asset value at beginning of period	$ 6.74		$ 9.54		$ 9.63		$ 10.27		$ 9.54		$ 10.70
Net investment income (loss) (a)	0.16		0.27		0.25		0.36		0.38		0.35
Net realized and unrealized gain (loss)	0.45		(2.67)		0.03		(0.66)		0.74		(1.18)
Total from investment operations	0.61		(2.40)		0.28		(0.30)		1.12		(0.83)
Less distributions:
From net investment income	(0.23)		(0.37)		(0.37)		(0.34)		(0.39)		(0.33)
Return of capital	—		(0.03)		—		—		—		—
Total distributions	(0.23)		(0.40)		(0.37)		(0.34)		(0.39)		(0.33)
Net asset value at end of period	$ 7.12		$ 6.74		$ 9.54		$ 9.63		$ 10.27		$ 9.54
Total investment return (b)	9.20%		(25.90)%		2.87%		(2.81)%		11.91%		(7.88)%
Ratios (to average net assets)/Supplemental Data:
Net investment income (loss)	4.41%††		3.31%		2.52%		3.68%		3.78%		3.39%
Net expenses (c)	2.39%††		2.31%		2.28%		2.24%		2.27%		2.22%
Expenses (before waiver/reimbursement) (c)	2.72%††		2.52%		2.45%		2.40%		2.31%		2.24%
Portfolio turnover rate	80%		116%		112%		102%		102%		44%
Net assets at end of period (in 000’s)	$ 1,084		$ 1,358		$ 3,511		$ 6,365		$ 11,150		$ 19,246

    

*	Unaudited.
††	Annualized.
(a)	Per share data based on average shares outstanding during the period.
(b)	Total investment return is calculated exclusive of sales charges and assumes the reinvestment of dividends and distributions. For periods of less than one year, total return is not annualized.
(c)	In addition to the fees and expenses which the Fund bears directly, it also indirectly bears a pro-rata share of the fees and expenses of the underlying funds in which it invests. Such indirect expenses are not included in the above expense ratios.

    

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

23

Financial Highlights selected per share data and ratios

	Six months ended April 30, 2023*		Year Ended October 31,
Class I			2022		2021		2020		2019		2018
Net asset value at beginning of period	$ 6.89		$ 9.75		$ 9.82		$ 10.48		$ 9.72		$ 10.90
Net investment income (loss) (a)	0.22		0.40		0.39		0.51		0.52		0.48
Net realized and unrealized gain (loss)	0.46		(2.74)		0.05		(0.69)		0.76		(1.20)
Total from investment operations	0.68		(2.34)		0.44		(0.18)		1.28		(0.72)
Less distributions:
From net investment income	(0.28)		(0.48)		(0.51)		(0.48)		(0.52)		(0.46)
Return of capital	—		(0.04)		—		—		—		—
Total distributions	(0.28)		(0.52)		(0.51)		(0.48)		(0.52)		(0.46)
Net asset value at end of period	$ 7.29		$ 6.89		$ 9.75		$ 9.82		$ 10.48		$ 9.72
Total investment return (b)	9.95%		(24.75)%		4.42%		(1.59)%		13.46%		(6.80)%
Ratios (to average net assets)/Supplemental Data:
Net investment income (loss)	5.94%††		4.89%		3.86%		5.09%		4.99%		4.60%
Net expenses (c)	0.85%††		0.85%		0.85%		0.85%		0.94%		1.01%
Expenses (before waiver/reimbursement) (c)	1.21%††		1.12%		1.06%		1.07%		1.01%		1.01%
Portfolio turnover rate	80%		116%		112%		102%		102%		44%
Net assets at end of period (in 000’s)	$ 3,648		$ 3,637		$ 5,729		$ 6,687		$ 17,100		$ 10,428

    

*	Unaudited.
††	Annualized.
(a)	Per share data based on average shares outstanding during the period.
(b)	Total investment return is calculated exclusive of sales charges and assumes the reinvestment of dividends and distributions. Class I shares are not subject to sales charges. For periods of less than one year, total return is not annualized.
(c)	In addition to the fees and expenses which the Fund bears directly, it also indirectly bears a pro-rata share of the fees and expenses of the underlying funds in which it invests. Such indirect expenses are not included in the above expense ratios.

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

24	MainStay Candriam Emerging Markets Debt Fund

Notes to Financial Statements (Unaudited)

Notes to Financial Statements (Unaudited) (continued)

Investments in mutual funds, including money market funds, are valued at their respective NAVs at the close of business each day on the valuation date. These securities are generally categorized as Level 1 in the hierarchy.

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

Debt securities (other than convertible and municipal bonds) are valued at the evaluated bid prices (evaluated mean prices in the case of convertible and municipal bonds) supplied by a pricing agent or broker selected by the Valuation Designee, in consultation with the Subadvisor. The evaluations are market-based measurements processed through a pricing application and represents the pricing agent’s good faith determination as to what a holder may receive in an orderly transaction under market conditions. The rules-based logic utilizes valuation techniques that reflect participants’ assumptions and vary by asset class and per methodology, maximizing the use of relevant observable data including quoted prices for similar assets, benchmark yield curves and market corroborated inputs. The evaluated bid or mean prices are deemed by the Valuation Designee, 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. Debt securities, including corporate bonds, U.S. government and federal agency bonds, municipal bonds, foreign bonds, convertible bonds, asset-backed securities and mortgage-backed securities are generally categorized as Level 2 in the hierarchy.

Foreign currency forward contracts are valued at their fair market values measured on the basis of the mean between the last current bid and ask prices based on dealer or exchange quotations and 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. Temporary cash investments that 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.

A portfolio investment may be classified as an illiquid investment under the Fund's written liquidity risk management program and related procedures (“Liquidity Program”). Illiquidity of an investment might prevent the sale of such investment at a time when the Manager or the Subadvisor might wish to sell, and these investments could have the effect of decreasing the overall level of the Fund's liquidity. Further, the lack of an established secondary market may make it more difficult to value illiquid investments, requiring the Fund to rely on judgments that may be somewhat subjective in measuring value, which could vary materially from the amount that the Fund could realize upon disposition. Difficulty in selling illiquid investments may result in a loss or may be costly to the Fund. An illiquid investment is any investment that the Manager or Subadvisor reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without the sale or disposition significantly changing the market value of the investment. The liquidity classification of each investment will be made using information obtained after reasonable inquiry and taking into account, among other things, relevant market, trading and investment-specific considerations in accordance with the Liquidity Program. Illiquid investments are often fair valued in accordance with the Fund's procedures described above. The liquidity of the Fund's investments was determined as of April 30, 2023, and can change at any time. Illiquid investments as of April 30, 2023, are shown in the Portfolio of Investments.

(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.

The Manager 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. The Manager 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 tax 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 Shareholders. Dividends and distributions are recorded on the ex-dividend date. The Fund intends to declare and pay dividends from net investment income, if any, at least

Notes to Financial Statements (Unaudited) (continued)

investing in these transactions. During the period the forward 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. Cash movement occurs on the settlement date. When the forward 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 Fund may purchase and sell foreign currency forward contracts for purposes of seeking to enhance portfolio returns and manage portfolio risk more efficiently. Foreign currency forward contracts may also be used to gain exposure to a particular currency or to hedge against the risk of loss due to changing currency exchange rates. Foreign currency forward contracts to purchase or sell a foreign currency may also be used in anticipation of future purchases or sales of securities denominated in foreign currency, even if the specific investments have not yet been selected.

The use of foreign currency forward contracts involves, to varying degrees, elements of risk in excess of the amount recognized in the Statement of Assets and Liabilities, including counterparty risk, market risk, leverage risk, operational risk, legal risk and liquidity risk. Counterparty risk is heightened for these instruments because foreign currency forward contracts are not exchange-traded and therefore no clearinghouse or exchange stands ready to meet the obligations under such contracts. Thus, the Fund faces the risk that its counterparties under such contracts may not perform their obligations. Market risk is the risk that the value of a foreign currency forward contract will depreciate due to unfavorable changes in exchange rates. Liquidity risk arises because the secondary market for foreign currency forward contracts may have less liquidity relative to markets for other securities and financial instruments. Liquidity risk also can arise when forward currency contracts create margin or settlement payment obligations for the Fund. Leverage risk is the risk that a foreign currency forward contract can magnify the Fund's gains and losses. Operational risk refers to risk related to potential operational issues (including documentation issues, settlement issues, systems failures, inadequate controls and human error), and legal risk refers to insufficient documentation, insufficient capacity or authority of the counterparty, or legality or enforceability of a foreign currency forward contract. Risks also arise from the possible movements in the foreign exchange rates underlying these instruments. While the Fund may enter into forward contracts to reduce currency exchange risks, changes in currency exchange rates may result in poorer overall performance for the Fund than if it had not engaged in such transactions. Exchange rate movements can be large, depending on the currency, and can last for extended periods of time, affecting the value of the Fund's assets. Moreover, there may be an imperfect correlation between the Fund's holdings of securities denominated in a particular currency and forward contracts entered into by the Fund. Such imperfect correlation may prevent the Fund from achieving the intended hedge or expose the Fund to the risk of currency exchange loss. The unrealized appreciation (depreciation) on forward contracts also reflects the Fund's exposure at the valuation date to credit loss in the event of a counterparty’s failure to

perform its obligations. Open foreign currency forward contracts as of April 30, 2023, are shown in the Portfolio of Investments.

(I) Foreign Currency Transactions. The Fund's books and records are maintained in U.S. dollars. Prices of securities denominated in foreign currency amounts are translated into U.S. dollars at the mean between the buying and selling rates last quoted by any major U.S. bank at the following dates:

(i) market value of investment securities, other assets and liabilities— at the valuation date; and

(ii) purchases and sales of investment securities, income and expenses—at the date of such transactions.

The assets and liabilities that are denominated in foreign currency amounts are presented at the exchange rates and market values at the close of the period. The realized and unrealized changes in net assets arising from fluctuations in exchange rates and market prices of securities are not separately presented.

Net realized gain (loss) on foreign currency transactions represents net currency gains or losses realized as a result of differences between the amounts of securities sale proceeds or purchase cost, dividends, interest and withholding taxes as recorded on the Fund's books, and the U.S. dollar equivalent amount actually received or paid. Net currency gains or losses from valuing such foreign currency denominated assets and liabilities, other than investments at valuation date exchange rates, are reflected in unrealized foreign exchange gains or losses.

(J) 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”). If the Fund engages in securities lending, the Fund will lend through its custodian, JPMorgan Chase Bank, N.A., ("JPMorgan"), acting as securities lending agent on behalf of the Fund. Under the current arrangement, JPMorgan will manage the Fund's collateral in accordance with the securities lending agency agreement between the Fund and JPMorgan, and indemnify the Fund against counterparty risk. The loans will be collateralized by cash (which may be invested in a money market fund) and/or non-cash collateral (which may include U.S. Treasury securities and/or U.S. government agency securities issued or guaranteed by the United States government or its agencies or instrumentalities) at least equal at all times to the market value of the securities loaned. Non-cash collateral held at year end is segregated and cannot be transferred by the Fund. The Fund bears the risk of delay in recovery of, or loss of rights in, the securities loaned. 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 cash collateral. The Fund will receive compensation for lending its securities in the form of fees or it will retain a portion of interest earned on the investment of any cash 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

Notes to Financial Statements (Unaudited) (continued)

Fair value of derivative instruments as of April 30, 2023:

Asset Derivatives	Interest Rate Contracts Risk	Total
Futures Contracts - Net Assets—Net unrealized appreciation on futures contracts (a)	$27,332	$27,332
Total Fair Value	$27,332	$27,332

    

(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.

    

Liability Derivatives	Foreign Exchange Contracts Risk	Interest Rate Contracts Risk	Total
Futures Contracts - Net Assets—Net unrealized depreciation on futures contracts (a)	$ —	$(60,371)	$ (60,371)
Forward Contracts - Unrealized depreciation on foreign currency forward contracts	(83,876)	—	(83,876)
Total Fair Value	$(83,876)	$(60,371)	$(144,247)

    

(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 April 30, 2023:

Net Realized Gain (Loss) from:	Foreign Exchange Contracts Risk	Interest Rate Contracts Risk	Total
Futures Contracts	$ —	$158,689	$158,689
Forward Contracts	(65,950)	—	(65,950)
Total Net Realized Gain (Loss)	$(65,950)	$158,689	$ 92,739

    

Net Change in Unrealized Appreciation (Depreciation)	Foreign Exchange Contracts Risk	Interest Rate Contracts Risk	Total
Futures Contracts	$ —	$(34,263)	$ (34,263)
Forward Contracts	(83,876)	—	(83,876)
Total Net Change in Unrealized Appreciation (Depreciation)	$(83,876)	$(34,263)	$(118,139)

    

Average Notional Amount	Total
Futures Contracts Long (a)	$13,991,788
Futures Contracts Short (a)	$ (2,935,717)
Forward Contracts Short (a)	$ (5,027,251)

    

(a)	Positions were open five months during the reporting period.

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 the portion of the compensation of the Chief Compliance Officer attributable to the Fund. Candriam (the "Subadvisor"), a registered investment adviser and an indirect, wholly-owned subsidiary of New York Life, serves as the 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 Candriam, New York Life Investments pays for the services of the Subadvisor.

Pursuant to the Management Agreement, the Fund pays the Manager a monthly fee for the services performed and the facilities furnished at an annual rate of the Fund’s average daily net assets as follows: 0.70% to $500 million and 0.65% in excess of $500 million. During the six-month period ended April 30, 2023, the effective management fee rate was 0.70% of the Fund’s average daily net assets, exclusive of any applicable waivers/reimbursements.

New York Life Investments has contractually agreed to waive fees and/or reimburse expenses so that Total Annual Fund Operating Expenses (excluding taxes, interest, litigation, extraordinary expenses, brokerage and other transaction expenses relating to the purchase or sale of portfolio investments and acquired (underlying) fund fees and expenses) do not exceed the following percentages of daily net assets: Class A, 1.15% and Class I, 0.85%. New York Life Investments will apply an equivalent waiver or reimbursement, in an equal number of basis points of the Class A shares waiver/reimbursement to the Investor Class, Class B and Class C shares. This agreement will remain in effect until February 28, 2024, and shall renew automatically for one-year terms unless New York Life Investments provides written notice of termination prior to the start of the next term or upon approval of the Board.

During the six-month period ended April 30, 2023, New York Life Investments earned fees from the Fund in the amount of $223,117 and waived fees and/or reimbursed expenses, including the waiver/reimbursement of certain class specific expenses in the amount of $100,349 and paid the Subadvisor fees in the amount of $62,157.

JPMorgan 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 NAVs of the Fund, maintaining the general ledger and sub-ledger accounts for the

Notes to Financial Statements (Unaudited) (continued)

During the year ended October 31, 2022, the tax character of distributions paid as reflected in the Statements of Changes in Net Assets was as follows:

	2022
Distributions paid from:
Ordinary Income	$4,543,692
Return of Capital	348,479
Total	$4,892,171

Note 5–Custodian

JPMorgan 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–Line of Credit

The Fund and certain other funds managed by New York Life Investments maintain a line of credit with a syndicate of banks in order to secure a source of funds for temporary purposes to meet unanticipated or excessive redemption requests.

Effective July 26, 2022, under the credit agreement (the “Credit Agreement”), the aggregate commitment amount is $600,000,000 with an additional uncommitted amount of $100,000,000. The commitment fee is an annual rate of 0.15% of the average commitment amount payable quarterly, regardless of usage, to JPMorgan, who serves as the agent to the syndicate. The commitment fee is allocated among the Fund and certain other funds managed by New York Life Investments based upon their respective net assets and other factors. Interest on any revolving credit loan is charged based upon the Federal Funds Rate, Daily Simple Secured Overnight Financing Rate ("SOFR") + 0.10%, or the Overnight Bank Funding Rate, whichever is higher. The Credit Agreement expires on July 25, 2023, although the Fund, certain other funds managed by New York Life Investments and the syndicate of banks may renew the Credit Agreement for an additional year on the same or different terms or enter into a credit agreement with a different syndicate of banks. Prior to July 26, 2022, the aggregate commitment amount and the commitment fee were the same as those under the current Credit Agreement. During the six-month period ended April 30, 2023, there were no borrowings made or outstanding with respect to the Fund under the Credit Agreement.

Note 7–Interfund Lending Program

Pursuant to an exemptive order issued by the SEC, the Fund, along with certain other funds managed by New York Life Investments, may participate in an interfund lending program. The interfund lending program provides an alternative credit facility that permits the Fund and certain other funds managed by New York Life Investments to lend or borrow money for temporary purposes directly to or from one another, subject to the conditions of the exemptive order. During the six-month

period ended April 30, 2023, there were no interfund loans made or outstanding with respect to the Fund.

Note 8–Purchases and Sales of Securities (in 000’s)

During the six-month period ended April 30, 2023, purchases and sales of securities, other than short-term securities, were $45,850 and $51,145, respectively.

Note 9–Capital Share Transactions

Transactions in capital shares for the six-month period ended April 30, 2023 and the year ended October 31, 2022, were as follows:

Class A	Shares	Amount
Six-month period ended April 30, 2023:
Shares sold	1,403,685	$ 10,207,797
Shares issued to shareholders in reinvestment of distributions	241,644	1,760,830
Shares redeemed	(2,120,514)	(15,480,843)
Net increase (decrease) in shares outstanding before conversion	(475,185)	(3,512,216)
Shares converted into Class A (See Note 1)	31,743	230,702
Shares converted from Class A (See Note 1)	(8,487)	(62,296)
Net increase (decrease)	(451,929)	$ (3,343,810)
Year ended October 31, 2022:
Shares sold	1,316,634	$ 10,780,850
Shares issued to shareholders in reinvestment of distributions	441,165	3,682,467
Shares redeemed	(3,131,520)	(25,516,770)
Net increase (decrease) in shares outstanding before conversion	(1,373,721)	(11,053,453)
Shares converted into Class A (See Note 1)	26,691	222,143
Shares converted from Class A (See Note 1)	(813)	(7,369)
Net increase (decrease)	(1,347,843)	$(10,838,679)

Notes to Financial Statements (Unaudited) (continued)

changes and supply chain disruptions, may occur and could significantly impact the Fund, issuers, industries, governments and other systems, including the financial markets. Developments that disrupt global economies and financial markets, such as COVID-19, the conflict in Ukraine, and the failures of certain U.S. and non-U.S. banks, may magnify factors that affect the Fund's performance.

Note 11–Subsequent Events

In connection with the preparation of the financial statements of the Fund as of and for the six-month period ended April 30, 2023, events and transactions subsequent to April 30, 2023, through the date the financial statements were issued have been evaluated by the Manager for possible adjustment and/or disclosure. No subsequent events requiring financial statement adjustment or disclosure have been identified.

35

Board Consideration and Approval of Management Agreement and Subadvisory Agreement  (Unaudited)

The Trustees noted that, throughout the year, the Trustees are afforded an opportunity to ask questions of, and request additional information or materials from, New York Life Investments and Candriam.  The Board’s decision with respect to each of the Advisory Agreements may have also been based, in part, on the Board’s knowledge of New York Life Investments and Candriam resulting from, among other things, the Board’s consideration of each of the Advisory Agreements in prior years, the advisory agreements for other funds in the MainStay Group of Funds, the Board’s review throughout the year of the performance and operations of other funds in the MainStay Group of Funds and each Trustee’s business judgment and industry experience.  In addition to considering the above-referenced factors, the Board observed that in the marketplace there are a range of investment options available to investors and that the Fund’s shareholders, having had the opportunity to consider other investment options, have chosen to invest in the Fund. 

The factors that figured prominently in the Board’s decision to approve the continuation of each of the Advisory Agreements during its December 6–7, 2022 meeting are summarized in more detail below.

Nature, Extent and Quality of Services Provided by New York Life Investments and Candriam

The Board examined the nature, extent and quality of the services that New York Life Investments provides to the Fund.  The Board evaluated New York Life Investments’ experience and capabilities in serving as manager of the Fund and considered that the Fund operates in a “manager-of-managers” structure.  The Board also considered New York Life Investments’ responsibilities and services provided pursuant to this structure, including overseeing the services provided by Candriam, evaluating the performance of Candriam, making recommendations to the Board as to whether the Subadvisory Agreement should be renewed, modified or terminated and periodically reporting to the Board regarding the results of New York Life Investments’ evaluation and monitoring functions. The Board noted that New York Life Investments manages other mutual funds, serves a variety of other investment advisory clients, including other pooled investment vehicles, and has experience overseeing mutual fund service providers, including subadvisors.  The Board considered the experience of senior personnel at New York Life Investments providing management and administrative and other non-advisory services to the Fund.  The Board observed that New York Life Investments devotes significant resources and time to providing management and administrative and other non-advisory services to the Fund, including New York Life Investments’ oversight and due diligence reviews of Candriam and ongoing analysis of, and interactions with, Candriam with respect to, among other things, the Fund’s investment performance and risks as well as Candriam’s investment capabilities and subadvisory services with respect to the Fund.

The Board also considered the range of services that New York Life Investments provides to the Fund under the terms of the Management Agreement, including: (i) fund accounting and ongoing supervisory services provided by New York Life Investments’ Fund Administration and Accounting Group; (ii) investment supervisory and analytical services

provided by New York Life Investments’ Investment Consulting Group; (iii) compliance services provided by the Trust’s Chief Compliance Officer as well as New York Life Investments’ compliance department, including supervision and implementation of the Fund’s compliance program; (iv) legal services provided by New York Life Investments’ Office of the General Counsel; and (v) risk management monitoring and analysis by compliance and investment personnel.  In addition, the Board considered New York Life Investments’ willingness to invest in personnel and other resources, such as cyber security, information security and business continuity planning, designed to benefit the Fund and noted that New York Life Investments is responsible for compensating the Trust’s officers, except for a portion of the salary of the Trust’s Chief Compliance Officer.  The Board recognized that New York Life Investments provides certain other non-advisory services to the Fund and has provided an increasingly broad array of non-advisory services to the MainStay Group of Funds as a result of regulatory and other developments, including in connection with the implementation of the MainStay Group of Funds’ derivatives risk management program and policies and procedures adopted pursuant to Rule 18f-4 under the 1940 Act.  The Board considered benefits to the Fund’s shareholders from the Fund being part of the MainStay Group of Funds, including the ability to exchange investments between the same class of shares of funds in the MainStay Group of Funds, including without the imposition of a sales charge (if any).

The Board also examined the range, and the nature, extent and quality, of the investment advisory services that Candriam provides to the Fund and considered the terms of each of the Advisory Agreements.  The Board evaluated Candriam’s experience and performance in serving as subadvisor to the Fund and advising other portfolios and Candriam’s track record and experience in providing investment advisory services as well as the experience of investment advisory, senior management and administrative personnel at Candriam. The Board considered New York Life Investments’ and Candriam’s overall resources, legal and compliance environment, capabilities, reputation, financial condition and history.  In addition to information provided in connection with quarterly meetings with the Trust’s Chief Compliance Officer, the Board considered information regarding the compliance policies and procedures of New York Life Investments and Candriam and acknowledged their commitment to further developing and strengthening compliance programs relating to the Fund.  The Board also considered Candriam’s ability to recruit and retain qualified investment professionals and willingness to invest in personnel and other resources to service and support the Fund.  In this regard, the Board considered the qualifications and experience of the Fund’s portfolio managers, the number of accounts managed by the portfolio managers and the method for compensating the portfolio managers.

In addition, the Board considered information provided by New York Life Investments and Candriam regarding the operations of their respective business continuity plans in response to the COVID-19 pandemic and the continued remote work environment. 

Board Consideration and Approval of Management Agreement and Subadvisory Agreement  (Unaudited) (continued)

The Board observed that, in addition to fees earned by New York Life Investments under the Management Agreement for managing the Fund, New York Life Investments’ affiliates also earn revenues from serving the Fund in various other capacities, including as the Fund’s transfer agent and distributor.  The Board considered information about these other revenues and their impact on the profitability of the relationship with the Fund to New York Life Investments and its affiliates.  The Board noted that, although it assessed the overall profitability of the relationship with the Fund to New York Life Investments and its affiliates as part of the contract review process, when considering the reasonableness of the fee paid to New York Life Investments under the Management Agreement, the Board considered the profitability of New York Life Investments’ relationship with the Fund on a pre-tax basis and without regard to distribution expenses incurred by New York Life Investments from its own resources.

After evaluating the information deemed relevant by the Trustees, the Board concluded that any profits realized by New York Life Investments and its affiliates, including Candriam, due to their relationships with the Fund were not excessive and other expected benefits that may accrue to New York Life Investments and its affiliates, including Candriam, are reasonable.

Management and Subadvisory Fees and Total Ordinary Operating Expenses

The Board evaluated the reasonableness of the fee paid under each of the Advisory Agreements and the Fund’s total ordinary operating expenses. The Board primarily considered the reasonableness of the management fee paid by the Fund to New York Life Investments because the subadvisory fee paid to Candriam is paid by New York Life Investments, not the Fund.  The Board also considered the reasonableness of the subadvisory fee paid by New York Life Investments and the amount of the management fee retained by New York Life Investments.

In assessing the reasonableness of the Fund’s fees and expenses, the Board primarily considered comparative data provided by ISS on the fees and expenses charged by similar mutual funds managed by other investment advisers. The Board reviewed the methodology used by ISS to construct the group of peer funds for comparative purposes. In addition, the Board considered information provided by New York Life Investments and Candriam on fees charged to other investment advisory clients, including institutional separate accounts and/or other funds that follow investment strategies similar to those of the Fund, if any.  The Board considered the contractual management fee schedules of the Fund as compared to those of such other investment advisory clients, taking into account the rationale for any differences in fee schedules.  The Board also took into account information provided by New York Life Investments about the more extensive scope of services provided to registered investment companies, such as the Fund, as compared with other investment advisory clients.  Additionally, the Board considered the impact of contractual breakpoints, voluntary waivers and expense limitation arrangements on the Fund’s net management fee and

expenses.  The Board also considered that in proposing fees for the Fund, New York Life Investments considers the competitive marketplace for mutual funds. 

The Board took into account information from New York Life Investments, as provided in connection with the Board’s June 2022 meeting, regarding the reasonableness of the Fund’s transfer agent fee schedule, including industry data demonstrating that the fees that NYLIM Service Company LLC, an affiliate of New York Life Investments and the Fund’s transfer agent, charges the Fund are within the range of fees charged by transfer agents to other mutual funds.  In addition, the Board considered NYLIM Service Company LLC’s profitability in connection with the transfer agent services it provides to the Fund.  The Board also took into account information provided by NYLIM Service Company LLC regarding the sub-transfer agency payments it made to intermediaries in connection with the provision of sub-transfer agency services to the Fund.

The Board considered the extent to which transfer agent fees contributed to the total expenses of the Fund.  The Board acknowledged the role that the MainStay Group of Funds historically has played in serving the investment needs of New York Life Insurance Company customers, who often maintain smaller account balances than other shareholders of funds, and the impact of small accounts on the expense ratios of Fund share classes.  The Board also recognized measures that it and New York Life Investments have taken intended to mitigate the effect of small accounts on the expense ratios of Fund share classes, including through the imposition of an expense limitation on net transfer agency expenses.  The Board also considered that NYLIM Service Company LLC had waived its contractual cost of living adjustments during the seven years prior to 2021.

Based on the factors outlined above, among other considerations, the Board concluded that the Fund’s management fee and total ordinary operating expenses are within a range that is competitive and support a conclusion that these fees and expenses are reasonable.

Economies of Scale

The Board considered information regarding economies of scale, including whether economies of scale may exist for the Fund and whether the Fund’s expense structure permits any economies of scale to be appropriately shared with the Fund’s shareholders.  The Board also considered a report from New York Life Investments, previously prepared at the request of the Board, that addressed economies of scale, including with respect to the mutual fund business generally, and the various ways in which the benefits of economies of scale may be shared with the funds in the MainStay Group of Funds.  Although the Board recognized the difficulty of determining economies of scale with precision, the Board acknowledged that economies of scale may be shared with the Fund in a number of ways, including, for example, through the imposition of fee breakpoints, initially setting management fee rates at scale or making additional investments to enhance the services provided to the Fund.  The Board reviewed information from New York Life Investments showing how the Fund’s management fee schedule compared to fee schedules of other

Board Consideration and Approval of Management Agreement and Subadvisory Agreement  (Unaudited) (continued)

funds and accounts managed by New York Life Investments.  The Board also reviewed information from ISS showing how the Fund’s management fee schedule compared with fees paid for similar services by peer funds at varying asset levels. 

Based on this information, the Board concluded that economies of scale are appropriately shared for the benefit of the Fund’s shareholders through the Fund’s expense structure and other methods to share benefits from economies of scale. 

Conclusion

On the basis of the information and factors summarized above, among other information and factors deemed relevant by the Trustees, and the evaluation thereof, the Board unanimously voted to approve the continuation of each of the Advisory Agreements.

40	MainStay Candriam Emerging Markets Debt Fund

Discussion of the Operation and Effectiveness of the Fund's Liquidity Risk Management Program (Unaudited)

In compliance with Rule 22e-4 under the Investment Company Act of 1940, as amended (the “Liquidity Rule”), the Fund has adopted and implemented a liquidity risk management program (the “Program”), which New York Life Investment Management LLC believes is reasonably designed to assess and manage the Fund's liquidity risk. A Fund's liquidity risk is the risk that the Fund could not meet requests to redeem shares issued by the Fund without significant dilution of the remaining investors’ interests in the Fund. The Board of Trustees of The MainStay Funds (the "Board") previously approved the designation of New York Life Investment Management LLC as administrator of the Program (the “Administrator”). The Administrator has established a Liquidity Risk Management Committee to assist the Administrator in the implementation and day-to-day administration of the Program and to otherwise support the Administrator in fulfilling its responsibilities under the Program.

At a meeting of the Board held on February 28, 2023, the Administrator provided the Board with a written report addressing the Program’s operation and assessing the adequacy and effectiveness of its implementation for the period from January 1, 2022, through December 31, 2022 (the "Review Period"), as required under the Liquidity Rule. The report noted that the Administrator concluded that (i) the Program operated effectively to assess and manage the Fund's liquidity risk, (ii) the Program has been and continues to be adequately and effectively implemented to monitor and, as applicable, respond to the Fund's liquidity developments and (iii) the Fund's investment strategy continues to be appropriate for an open-end fund. In addition, the report summarized the operation of the Program and the information and factors considered by the Administrator in its assessment of the Program’s implementation, such as the liquidity risk assessment framework and the liquidity classification methodologies, and discussed notable geopolitical, market and other economic events that impacted liquidity risk during the Review Period.

In accordance with the Program, the Fund's liquidity risk is assessed no less frequently than annually taking into consideration certain factors, as applicable, such as (i) investment strategy and liquidity of portfolio investments, (ii) short-term and long-term cash flow projections, and (iii) holdings of cash and cash equivalents, as well as borrowing arrangements and other funding sources. Certain factors are considered under both normal and reasonably foreseeable stressed conditions.

Each Fund portfolio investment is classified into one of four liquidity categories. The classification is based on a determination of the number of days it is reasonably expected to take to convert the investment into cash, or sell or dispose of the investment, in current market conditions without significantly changing the market value of the investment. The Administrator has delegated liquidity classification determinations to the Fund’s subadvisor, subject to appropriate oversight by the Administrator, and liquidity classification determinations are made by taking into account the Fund's reasonably anticipated trade size, various market, trading and investment-specific considerations, as well as market depth, and, in certain cases, third-party vendor data.

The Liquidity Rule requires funds that do not primarily hold assets that are highly liquid investments to adopt a minimum amount of net assets that must be invested in highly liquid investments that are assets (an “HLIM”). In addition, the Liquidity Rule limits a fund's investments in illiquid investments. Specifically, the Liquidity Rule prohibits acquisition of illiquid investments if, immediately after acquisition, doing so would result in a fund holding more than 15% of its net assets in illiquid investments that are assets. The Program includes provisions reasonably designed to determine, periodically review and comply with the HLIM requirement, as applicable, and to comply with the 15% limit on illiquid investments.

There can be no assurance that the Program will achieve its objectives under all circumstances in the future. Please refer to the Fund's prospectus for more information regarding the Fund's exposure to liquidity risk and other risks to which it may be subject.

41

Proxy Voting Policies and Procedures and Proxy Voting Record

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. A description of the policies and procedures that are used to vote proxies relating to portfolio securities of the Fund is available free of charge upon request by calling 800-624-6782 or visiting the SEC’s website at www.sec.gov. The most recent Form N-PX or proxy voting record is available free of charge upon request by calling 800-624-6782; visiting newyorklifeinvestments.com; or visiting 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 60 days after its first and third fiscal quarter on Form N-PORT. The Fund's holdings report is available free of charge upon request by calling New York Life Investments at 800-624-6782.

MainStay Funds

---

Not part of the Semiannual Report

MainStay Income Builder Fund

Message from the President and Semiannual Report

Unaudited  |  April 30, 2023

Sign up for e-delivery of your shareholder reports. For full details on e-delivery, including who can participate and what you can receive via e-delivery,
please log in to newyorklifeinvestments.com/accounts.

Not FDIC/NCUA Insured

Not a Deposit

May Lose Value

No Bank Guarantee

Not Insured by Any Government Agency

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Message from the 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
Investment and Performance Comparison	5
Portfolio Management Discussion and Analysis	9
Portfolio of Investments	13
Financial Statements	31
Notes to Financial Statements	43
Board Consideration and Approval of Management Agreement and Subadvisory Agreements	57
Discussion of the Operation and Effectiveness of the Fund's Liquidity Risk Management Program	62
Proxy Voting Policies and Procedures and Proxy Voting Record	63
Shareholder Reports and Quarterly Portfolio Disclosure	63

Investors should refer to the Fund’s Summary Prospectus and/or Prospectus and consider the Fund’s investment objectives, strategies, risks, charges and expenses carefully before investing. The Summary Prospectus and/or Prospectus contain this and other information about the Fund. You may obtain copies of the Fund’s Summary Prospectus, Prospectus and Statement of Additional Information, which includes information about The MainStay Funds' Trustees, free of charge, upon request, by calling toll-free 800-624-6782, by writing to NYLIFE Distributors LLC, Attn: MainStay Marketing Department, 30 Hudson Street, Jersey City, NJ 07302 or by sending an e-mail to MainStayShareholderServices@nylim.com. These documents are also available via the MainStay Funds’ website at newyorklifeinvestments.com. Please read the Fund’s Summary Prospectus and/or Prospectus carefully before investing.

Investment and Performance Comparison (Unaudited)

Performance data quoted represents past performance. 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. The graph below depicts the historical performance of Class I shares of the Fund. Performance will vary from class to class based on differences in class-specific expenses and sales charges. For performance information current to the most recent month-end, please call 800-624-6782 or visit newyorklifeinvestments.com.

The performance table and graph do not reflect the deduction of taxes that a shareholder would pay on distributions or Fund share redemptions. Total returns reflect maximum applicable sales charges as indicated in the table below, if any, changes in share price, and reinvestment of dividend and capital gain distributions. The graph assumes the initial investment amount shown below and reflects the deduction of all sales charges that would have applied for the period of investment. Performance figures may reflect certain fee waivers and/or expense limitations, without which total returns may have been lower. For more information on share classes and current fee waivers and/or expense limitations (if any), please refer to the Notes to Financial Statements.

Average Annual Total Returns for the Period-Ended April 30, 2023
Class	Sales Charge		Inception Date	Six Months1	One Year	Five Years	Ten Years or Since Inception	Gross Expense Ratio2
Class A Shares3	Maximum 3.00% Initial Sales Charge	With sales charges	1/3/1995	4.45%	-3.20%	2.71%	4.19%	1.02%
		Excluding sales charges		7.68	-0.21	3.88	4.78	1.02
Investor Class Shares4	Maximum 2.50% Initial Sales Charge	With sales charges	2/28/2008	4.86	-2.91	2.53	4.01	1.20
		Excluding sales charges		7.55	-0.42	3.70	4.60	1.20
Class B Shares5	Maximum 5.00% CDSC	With sales charges	12/29/1987	2.14	-6.03	2.58	3.82	1.95
	if Redeemed Within the First Six Years of Purchase	Excluding sales charges		7.14	-1.17	2.93	3.82	1.95
Class C Shares	Maximum 1.00% CDSC	With sales charges	9/1/1998	6.16	-2.15	2.92	3.82	1.95
	if Redeemed Within One Year of Purchase	Excluding sales charges		7.16	-1.18	2.92	3.82	1.95
Class I Shares	No Sales Charge		1/2/2004	7.78	-0.01	4.13	5.04	0.77
Class R2 Shares	No Sales Charge		2/27/2015	7.60	-0.35	3.78	3.50	1.12
Class R3 Shares	No Sales Charge		2/29/2016	7.44	-0.61	3.50	5.08	1.37
Class R6 Shares	No Sales Charge		2/28/2018	7.83	0.07	4.23	4.06	0.68
SIMPLE Class Shares	No Sales Charge		8/31/2020	7.42	-0.65	N/A	1.43	1.38

    

1.	Not annualized.
2.	The gross expense ratios presented reflect the Fund’s “Total Annual Fund Operating Expenses” from the most recent Prospectus, as supplemented, and may differ from other expense ratios disclosed in this report.
3.	Prior to November 4, 2019, the maximum initial sales charge applicable was 5.50%, which is reflected in the applicable average annual total return figures shown.
4.	Prior to June 30, 2020, the maximum initial sales charge was 3.00%, which is reflected in the applicable average annual total return figures shown.
5.	Class B shares are closed to all new purchases as well as additional investments by existing Class B shareholders.

The footnotes on the next page are an integral part of the table and graph and should be carefully read in conjunction with them.

5

Benchmark Performance*	Six Months1	One Year	Five Years	Ten Years
MSCI World Index (Net)2	12.26%	3.18%	8.14%	8.71%
Bloomberg U.S. Aggregate Bond Index3	6.91	-0.43	1.18	1.32
Blended Benchmark Index4	10.14	1.99	5.65	5.94
Morningstar Global Allocation Category Average5	8.65	-0.75	3.26	3.94

    

*	Returns for indices reflect no deductions for fees, expenses or taxes, except for foreign withholding taxes where applicable. Results assume reinvestment of all dividends and capital gains. An investment cannot be made directly in an index.
1.	Not annualized.
2.	The MSCI World Index (Net) is the Fund's primary broad-based securities market index for comparison purposes. The MSCI World Index (Net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of developed markets.
3.	The Fund has selected the Bloomberg U.S. Aggregate Bond Index as a secondary benchmark. The Bloomberg U.S. Aggregate Bond Index measures performance of the investment-grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasurys, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
4.	The Fund has selected the Blended Benchmark Index as an additional benchmark. The Blended Benchmark Index consists of the 60% MSCI World Index and 40% of the Bloomberg U.S. Aggregate Bond Index, respectively.
5.	Morningstar Global Allocation Category Average funds seek to provide both capital appreciation and income by investing in three major areas: stocks, bonds, and cash. While these funds do explore the whole world, most of them focus on the U.S., Canada, Japan, and the larger markets in Europe. It is rare for such funds to invest more than 10% of their assets in emerging markets. These funds typically have at least 10% of assets in bonds, less than 70% of assets in stocks, and at least 40% of assets in non-U.S. stocks or bonds.

The footnotes on the preceding page are an integral part of the table and graph and should be carefully read in conjunction with them.

6	MainStay Income Builder Fund

Cost in Dollars of a $1,000 Investment in MainStay Income Builder Fund (Unaudited)

The example below is intended to describe the fees and expenses borne by shareholders during the six-month period from November 1, 2022 to April 30, 2023, and the impact of those costs on your investment.

Example

As a shareholder of the Fund you incur two types of costs: (1) transaction costs, including exchange fees and sales charges (loads) on purchases (as applicable), and (2) ongoing costs, including management fees, distribution and/or service (12b-1) fees and other Fund expenses (as applicable). This example is intended to help you understand your ongoing costs (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 made at the beginning of the six-month period and held for the entire period from November 1, 2022 to April 30, 2023.

This example illustrates your Fund’s ongoing costs in two ways:

Actual Expenses

The second and third data columns in the table below provide information about actual account values and actual expenses. You may use the information in these columns, together with the amount you invested, to estimate the expenses that you paid during the six months ended April 30, 2023. Simply divide your account value by $1,000 (for example, an

$8,600 account value divided by $1,000 = 8.6), then multiply the result by the number under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The fourth and fifth data columns in the table below provide information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balances or expenses you paid for the six-month period shown. You may use this information to compare the ongoing costs of investing in the Fund with the ongoing costs of investing in other mutual funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other mutual funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as exchange fees or sales charges (loads). Therefore, the fourth and fifth data columns of the table are useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

7

Portfolio Composition as of April 30, 2023 (Unaudited)

See Portfolio of Investments beginning on page 13 for specific holdings within these categories. The Fund's holdings are subject to change.

Top Ten Holdings and/or Issuers Held as of April 30, 2023 (excluding short-term investments) (Unaudited)

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8	MainStay Income Builder Fund

Portfolio Management Discussion and Analysis (Unaudited)

Questions answered by portfolio managers Jae S. Yoon, CFA, and Jonathan Swaney of New York Life Investment Management LLC, the Fund’s Manager; Stephen R. Cianci, CFA,¹ and Neil Moriarty III, of MacKay Shields LLC, the Subadvisor for the fixed-income portion of the Fund; and William W. Priest, CFA, Michael A. Welhoelter, CFA, John Tobin, PhD, CFA, and Kera Van Valen, CFA, of Epoch Investment Partners, Inc., the Subadvisor for the equity portion of the Fund.

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Analog Devices and German-based telecommunications services provider Deutsche Telekom.

Analog Devices is a developer of analog integrated circuits and digital signal processors. The company has a history of technological innovation and driving sales into adjacent markets. Shares rose, along with those of most other semiconductor companies, as investors looked past the current industry inventory digestion to a potential rebound in the second half of 2023. Analog Devices has bucked the trend in slack industry demand due to its industrial and automotive exposure. The company has a history of returning cash to shareholders through a combination of dividends, share repurchases and debt reduction.

Deutsche Telekom is Germany’s largest telecommunication services provider and one of the largest in the United States, with additional operations in greater Europe. Shares outperformed due to a combination of sustained European growth, including industry-leading results in Germany, and outperformance at T-Mobile. The company’s U.S. operations gained share, and cash flow began inflecting higher as integration expenses from Sprint declined. The company pays a well-covered dividend and is reducing debt in the United States following its merger with Sprint.

Among the most significant detractors from the Fund’s absolute performance during the same period were regional bank KeyCorp and insurer MetLife, both based in the United States.

KeyCorp maintains branches in 15 states in the Northeast, Midwest, and Northwest United States. The company has a valuable, low-cost deposit franchise, a diversified loan portfolio and a well-capitalized balance sheet, which we believe should allow Keycorp to earn mid-teens returns on equity on a mid-cycle basis. Shares declined late in the reporting period along with banking industry peers when the failures of Silicon Valley Bank and Signature Bank caused a crisis of confidence that reverberated across the entire sector. Although the crisis may result in higher near-term funding costs and increased retained capital levels for banks, we believe KeyCorp will continue to generate strong earnings that support attractive, growing dividends. We also expect the company to direct excess capital toward share buybacks during normal economic conditions.

MetLife serves retail and commercial customers with a comprehensive offering of insurance products, including life, disability, accident & health, dental, and annuities. In addition to its U.S. operations, the company has a significant international presence in Asia, Latin America, Europe, the Middle East and Africa. Shares traded down late in the reporting period as the banking turmoil described above unsettled the financial sector, although we don't believe MetLife's business performance will be impacted by these events. MetLife has a strong regulatory capital position, pays an attractive and growing dividend, and consistently uses excess capital to repurchase shares.

What were some of the largest purchases and sales in the equity portion of the Fund during the reporting period?

New positions initiated during the reporting period included U.K.-based asset manager Schroders and digital services and hardware provider Dell Technologies.

Schroders had $979B of assets under management (AUM) as of the end of the reporting period. The company has successfully diversified its AUM such that the revenue contribution from private assets and wealth management matches that from more volatile mutual funds and institutional assets. Schroders generates growth through positive net flows in most years that offset fee compression, while the relatively longer duration of private assets and wealth management helps provide cash flow stability through difficult market conditions. The company returns cash to shareholders through an attractive, well-covered dividend.

Dell serves the infrastructure marketplace by providing servers and data storage, as well as the consumer and commercial space with personal computing hardware and peripherals. Growth is driven by an increase in data storage, processing and computing needs, and by share capture through attractive technology and pricing. The company targets a return of 40–60% cash generation back to shareholders, which is achieved through a combination of a growing dividend and periodic share repurchases. Additional cash generation is directed to slight debt reduction and tuck-in mergers and acquisitions to broaden its addressable market.

The Fund’s most significant sales during the same period included closing its entire positions in Germany-based global chemicals company BASF and Japan-based video game maker Koei Tecmo.

BASF produces commodity and specialty chemicals with broad product offerings and a diverse geographic footprint. In the coming years, continuing high European natural gas prices and elevated capital expenditures are expected to lead to compressed operating margins, declining free cash flow, inadequate dividend coverage and rising debt, prompting us to exit the Fund’s position in favor of more attractive shareholder yield names.

Koei Tecmo makes video games for the mobile, PC, Sony PlayStation, Microsoft Xbox, and Nintendo Switch markets. The company’s games have a strong following based on its proprietary internally developed intellectual property (IP). It also licenses IP from others to create games that support a repeatable software sales cycle. Repeat title sales have been lower than expected, and the company has yet to launch a hit title in China, putting into question their ability to grow cash flow. With inflationary pressures increasing the investment needed to grow outside of Japan and expand the title base, the dividend looked less assured given the company’s distribution policy. Accordingly, we chose to exit the Fund’s position in favor of other investment opportunities.

How did sector and country weightings change in the equity portion of the Fund during the reporting period?

During the reporting period, the Fund’s most significant sector allocation changes included increases in information technology and real estate, and decreases in financials and industrials. The Fund's most significant country allocation changes during the reporting period were increases in France and Germany, and reductions in the United States and Denmark. The Fund’s sector and country allocations are a result of our bottom-up, fundamental investment process, and reflect the companies and securities that we confidently believe can collect and distribute sustainable, growing shareholder yield.

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

As of April 30, 2023, the equity portion of the Fund’s largest sector positions on an absolute basis included information technology, health care and financials, while the smallest sector positions were real estate and materials. Compared to the MSCI World Index (Net), the Fund’s most overweight sector allocations were to utilities, a defensive sector that is typically well-represented in the Fund, and consumer staples. The Fund’s most significantly underweight allocations were to the information technology and consumer discretionary sectors.

What factors affected the relative performance of the fixed-income portion of the Fund during the reporting period?

The Fund’s performance relative to the Bloomberg U.S. Aggregate Bond Index benefited from overweight exposure to securitized products, high-yield corporates and emerging-markets credit as credit spreads⁵—which represent the level of compensation to investors—tightened during the reporting period. Performance varied across the ratings spectrum, term structure and asset type. Generally speaking, longer-duration assets underperformed shorter-duration assets, lower quality outperformed higher quality within the investment-grade segment of the market, and securitized assets outperformed unsecured credit. The Fund’s relatively long duration profile during the reporting period was also beneficial to returns. Conversely, the Fund’s underweight allocation to U.S. Treasury securities detracted from relative returns.

What was the duration strategy of the fixed-income portion of the Fund during the reporting period?

During the reporting period, the fixed-income portion of the Fund generally maintained a longer duration than that of the Bloomberg U.S. Aggregate Bond Index, which had a positive impact on relative returns. As of April 30, 2023, the duration of the fixed-income portion of the Fund was 6.7 years, compared to a duration of 6.3 years for the Bloomberg U.S. Aggregate Bond Index.

During the reporting period, which sectors were the strongest positive contributors to the relative performance of the fixed-income portion of the Fund and which sectors were particularly weak?

Relative to the Bloomberg U.S. Aggregate Bond Index, the strongest positive contributors to the performance of the fixed-income portion of the Fund included securitized securities, investment-grade corporates and emerging-markets credits. Underweight exposure to U.S. Treasury securities was a drag on performance, but was offset by investments in higher-yielding spread product.⁶

What were some of the largest purchases and sales in the fixed-income portion of the Fund during the reporting period?

The fixed-income portion of the Fund added exposure to Georgia Power, a fully regulated utility, because we saw attractive value on a risk-adjusted basis. Georgia Power benefits from stable and predictable cash flow generation and strong relationships with its regulators. We favor utilities exposure due to the defensive and predictable credit nature of these issuers and their ability to perform well, particularly in a recessionary scenario. The Fund also added a position in Charter Communications, based on attractive valuation. As one of the largest cable and communications providers in the United States, we consider Charter a core high-yield holding, with solid fundamentals and relatively non-cyclical operations.

We sold the Fund’s position in Howmet Aerospace for relative value reasons. Although Howmet is a strong high-yield credit rated BB+⁷ on an improving trajectory, in our opinion, the valuation already fully reflected any potential future improvement. At the time of sale, Howmet traded in line with, or better than, many

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low-BBB-rated⁸ investment-grade corporates. We also sold the Fund’s QVC holdings following a periodic credit review of the issuer. We concluded that, in light of worsening earnings trends, coupled with our cautious outlook on cyclical consumer spending, a stress event may materialize for the issuer in 2024, and likely in 2025.

How did the sector weightings of the fixed-income portion of the Fund change during the reporting period?

During the reporting period, the fixed-income portion of the Fund decreased its exposure to U.S. Treasury securities and high-yield corporate securities. During the same period, the Fund increased its exposure to residential mortgage securities and consumer asset-backed securities.

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

As of April 30, 2023, the fixed-income portion of the Fund held overweight exposure to high-grade and high-yield corporate bonds, as well as securitized product. As of the same date, the Fund held underweight exposure to U.S. Treasury securities and agency mortgages. 

8.

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.

12	MainStay Income Builder Fund

Portfolio of Investments April 30, 2023^{†^}(Unaudited)

Portfolio of Investments April 30, 2023^{†^}(Unaudited) (continued)

	Principal Amount	Value
Corporate Bonds (continued)
Banks (continued)
Bank of America Corp. (e) (continued)
Series MM
4.30%, due 1/28/25 (f)	$    1,424,000	$     1,288,702
Barclays plc (United Kingdom) (c)(f)
4.375% (5 Year Treasury Constant Maturity Rate + 3.41%), due 3/15/28	2,000,000	1,324,844
8.00% (5 Year Treasury Constant Maturity Rate + 5.431%), due 3/15/29	1,035,000	906,556
BNP Paribas SA (France) (a)
3.052%, due 1/13/31  (e)	1,170,000	1,011,870
4.625% (5 Year Treasury Constant Maturity Rate + 3.196%), due 1/12/27  (c)(f)	1,450,000	1,138,105
4.625% (5 Year Treasury Constant Maturity Rate + 3.34%), due 2/25/31  (c)(f)	2,090,000	1,482,646
7.75% (5 Year Treasury Constant Maturity Rate + 4.899%), due 8/16/29  (c)(f)	550,000	525,250
BPCE SA (France) (a)
2.045%, due 10/19/27  (e)	1,255,000	1,109,189
5.125%, due 1/18/28	910,000	911,444
Citigroup, Inc.
3.668%, due 7/24/28 (e)	1,180,000	1,116,984
3.98%, due 3/20/30 (e)	2,370,000	2,223,493
Series Y
4.15% (5 Year Treasury Constant Maturity Rate + 3.00%), due 11/15/26 (c)(f)	1,760,000	1,447,600
6.625%, due 6/15/32	770,000	831,767
Citizens Bank NA
6.064%, due 10/24/25 (e)	555,000	537,049
Citizens Financial Group, Inc.
2.638%, due 9/30/32	1,720,000	1,280,629
Credit Agricole SA
4.75% (5 Year Treasury Constant Maturity Rate + 3.237%), due 3/23/29 (France) (a)(c)(f)	2,340,000	1,799,460
Credit Suisse Group AG (Switzerland) (a)(e)
3.091%, due 5/14/32	1,930,000	1,545,565
6.442%, due 8/11/28	365,000	361,248
Deutsche Bank AG (Germany)
Series E
0.962%, due 11/8/23	1,555,000	1,505,664

	Principal Amount	Value
Banks (continued)
Deutsche Bank AG (Germany) (continued)
3.035%, due 5/28/32  (e)	$      600,000	$       478,594
5.371%, due 9/9/27	415,000	411,231
6.074% (SOFR + 1.219%), due 11/16/27  (c)	1,945,000	1,748,944
First Horizon Bank
5.75%, due 5/1/30	1,555,000	1,469,758
First Horizon Corp.
4.00%, due 5/26/25	2,100,000	1,963,223
Freedom Mortgage Corp.
7.625%, due 5/1/26 (a)	860,000	735,403
Goldman Sachs Group, Inc. (The)
1.431%, due 3/9/27 (e)	1,255,000	1,126,706
1.948%, due 10/21/27 (e)	1,435,000	1,285,029
1.992%, due 1/27/32 (e)	1,165,000	932,772
6.75%, due 10/1/37	829,000	907,249
HSBC Holdings plc
3.973%, due 5/22/30 (United Kingdom) (e)	1,350,000	1,242,045
Intesa Sanpaolo SpA
7.00%, due 11/21/25 (Italy) (a)	585,000	597,712
JPMorgan Chase & Co.
2.182%, due 6/1/28 (e)	1,800,000	1,616,842
Series HH
4.60%, due 2/1/25 (e)(f)	647,000	600,092
6.03% (SOFR + 1.18%), due 2/24/28 (c)(d)	1,995,000	1,997,021
Lloyds Banking Group plc (United Kingdom)
4.582%, due 12/10/25	1,038,000	993,631
4.65%, due 3/24/26	1,690,000	1,627,131
4.976% (1 Year Treasury Constant Maturity Rate + 2.30%), due 8/11/33  (c)	870,000	843,418
Macquarie Group Ltd.
2.871%, due 1/14/33 (Australia) (a)(e)	1,925,000	1,564,670
Mizuho Financial Group, Inc.
3.261% (1 Year Treasury Constant Maturity Rate + 1.25%), due 5/22/30 (Japan) (c)	795,000	712,552
Morgan Stanley
2.484%, due 9/16/36 (e)	2,115,000	1,625,612
2.511%, due 10/20/32 (e)	1,530,000	1,259,596
5.00%, due 11/24/25	1,160,000	1,161,930

Portfolio of Investments April 30, 2023^{†^}(Unaudited) (continued)