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Prospectus Summary | MainStay Winslow Large Cap Growth Fund

MainStay Winslow Large Cap Growth Fund

Investment Objective

The Fund seeks long-term growth of capital.

Fees and Expenses of the Fund

The table below describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the table and example below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the MainStay Funds. This amount may vary depending on the MainStay Fund in which you invest. In addition, different financial intermediary firms and financial professionals may impose different sales loads and waivers. More information about these and other discounts or waivers is available from your financial professional, in the "Information on Sales Charges" section starting on page 70 of the Prospectus and Appendix A – Intermediary-Specific Sales Charge Waivers and Discounts, and in the "Alternative Sales Arrangements" section on page 142 of the Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - Prospectus Summary - MainStay Winslow Large Cap Growth Fund	Class A		INVESTOR CLASS		Class B	[1]	Class C	Class I	Class R1	Class R2	Class R3	Class R6	SIMPLE CLASS
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)	5.50%		5.00%		none		none	none	none	none	none	none	none
Maximum Deferred Sales Charge (as a percentage)	none	[2]	none	[2]	5.00%		1.00%	none	none	none	none	none	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Prospectus Summary - MainStay Winslow Large Cap Growth Fund		Class A	INVESTOR CLASS	Class B	[2]	Class C	Class I	Class R1	Class R2	Class R3	Class R6	SIMPLE CLASS
Management Fees (as an annual percentage of the Fund's average daily net assets)	[1]	0.61%	0.61%	0.61%		0.61%	0.61%	0.61%	0.61%	0.61%	0.61%	0.61%
Distribution and/or Service (12b-1) Fees		0.25%	0.25%	1.00%		1.00%	none	none	0.25%	0.50%	none	0.50%
Other Expenses		0.08%	0.23%	0.23%		0.23%	0.08%	0.18%	0.18%	0.18%	0.02%	0.23%
Total Annual Fund Operating Expenses		0.94%	1.09%	1.84%		1.84%	0.69%	0.79%	1.04%	1.29%	0.63%	1.34%
Waivers / Reimbursements	[3]	(0.01%)	(0.01%)	(0.01%)		(0.01%)	(0.01%)	(0.01%)	(0.01%)	(0.01%)	(0.01%)	(0.01%)
Total Annual Fund Operating Expenses After Waivers / Reimbursements	[3]	0.93%	1.08%	1.83%		1.83%	0.68%	0.78%	1.03%	1.28%	0.62%	1.33%

Example

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated whether or not you redeem all of your shares at the end of those periods (except as indicated with respect to Class B and Class C shares). The Example reflects Class B and Class C shares converting into Investor Class shares in years 9-10; expenses could be lower if you are eligible to convert to Class A shares instead. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The Example reflects the contractual fee waiver and/or expense reimbursement arrangement, if applicable, for the current duration of the arrangement only. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Assuming redemption at end of period

Expense Example - Prospectus Summary - MainStay Winslow Large Cap Growth Fund - USD ($)	Class A	INVESTOR CLASS	Class B	Class C	Class I	Class R1	Class R2	Class R3	Class R6	SIMPLE CLASS
1 Year	$ 640	$ 605	$ 686	$ 286	$ 69	$ 80	$ 105	$ 130	$ 63	$ 135
3 Years	832	828	878	578	220	251	330	408	201	424
5 Years	1,041	1,070	1,195	995	383	438	573	707	350	733
10 Years	$ 1,640	$ 1,761	$ 1,961	$ 1,961	$ 858	$ 977	$ 1,270	$ 1,556	$ 785	$ 1,612

Assuming no redemption

Expense Example, No Redemption - Prospectus Summary - MainStay Winslow Large Cap Growth Fund - USD ($)	Class B	Class C
1 Year	$ 186	$ 186
3 Years	578	578
5 Years	995	995
10 Years	$ 1,961	$ 1,961

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 66% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its assets (net assets plus any borrowings for investment purposes) in large capitalization companies, which are companies having a market capitalization in excess of $4 billion at the time of purchase. Typically, Winslow Capital Management, LLC, the Fund's Subadvisor, invests substantially all of the Fund's investable assets in domestic securities. However, the Fund is permitted to invest up to 20% of its net assets in foreign securities. Generally, an issuer of a security is considered to be U.S. or foreign based on the issuer's "country of risk," as determined by a third-party service provider such as Bloomberg.

Investment Process: The Fund invests in those companies that the Subadvisor believes will provide an opportunity for achieving superior portfolio returns (i.e., returns in excess of the returns of the average stock mutual fund) over the long term. The Subadvisor seeks to invest in companies that have the potential for above-average future earnings and cash flow growth with management focused on shareholder value.

When purchasing stocks for the Fund, the Subadvisor looks for companies typically having some or all of the following attributes: addressing markets with growth opportunities; leads or gains in market share; identifiable and sustainable competitive advantages; managed by a team that can perpetuate the firm's competitive advantages; high, and preferably rising, returns on invested capital; deploys excess cash flow to enhance shareholder return; and demonstrates sound corporate governance. As part of its qualitative assessment of each potential investment, the Subadvisor evaluates the company’s non-financial performance among certain environmental, social and governance (“ESG”) factors. The Subadvisor then determines which ESG factors may be material to a company’s future financial performance. This involves an evaluation of how the company integrates particular ESG risks and opportunities into its corporate strategy through, for example, improving governance practices, aligning management team incentives and increasing transparency into its ESG practices. The Subadvisor may give consideration to ESG factors including, but not limited to, impact on or from climate change, natural resource use, waste management practices, human capital management, product safety, supply chain management, corporate governance, business ethics and advocacy for governmental policy.

ESG factors are evaluated by the Subadvisor based on data provided by independent ESG research vendors. The evaluation of ESG factors is integrated as one of several aspects of the Subadvisor’s investment process and the Subadvisor does not forgo potential investments strictly based on the evaluation of ESG factors.

The Subadvisor takes a "bottom-up" investment approach when selecting investments. This means it bases investment decisions on company specific factors, not general economic conditions.

Under normal market conditions, the Subadvisor employs a sell discipline pursuant to which it may sell some or all of its position in a stock when a stock becomes fully valued, the fundamental business prospects are deteriorating, or the position exceeds limits set by the Subadvisor.

Principal Risks

You can lose money by investing in the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. The investments selected by the Subadvisor may underperform the market in which the Fund invests or other investments. The Fund may receive large purchase or redemption orders which may have adverse effects on performance if the Fund were required to sell securities, invest cash or hold a relatively large amount of cash at times when it would not otherwise do so.

The principal risks of investing in the Fund are summarized below.

Market Risk: The value of the Fund’s investments may fluctuate because of changes in the markets in which the Fund invests, which could cause the Fund to underperform other funds with similar investment objectives and strategies. Such changes may be rapid and unpredictable. From time to time, markets may experience periods of stress for potentially prolonged periods that may result in: (i) increased market volatility; (ii) reduced market liquidity; and (iii) increased redemptions of Fund shares. Such conditions may add significantly to the risk of volatility in the net asset value of the Fund's shares.

Portfolio Management Risk: The investment strategies, practices and risk analyses used by the Subadvisor may not produce the desired results. The Subadvisor may give consideration to certain ESG criteria when evaluating an investment opportunity. The application of ESG criteria may result in the Fund (i) having exposure to certain securities or industry sectors that are significantly different than the composition of the Fund's benchmark; and (ii) performing differently than other funds and strategies in its peer group that do not take into account ESG criteria or the Fund's benchmark.

Equity Securities Risk: Investments in common stocks and other equity securities are particularly subject to the risk of changing economic, stock market, industry and company conditions and the risks inherent in the portfolio managers' ability to anticipate such changes that can adversely affect the value of the Fund's holdings.

Market Capitalization Risk: To the extent the Fund invests in securities issued by small-, mid-, or large-cap companies, the Fund will be subject to the risks associated with securities issued by companies of the applicable market capitalization.  Securities of small-cap and mid-cap companies may be subject to greater price volatility, significantly lower trading volumes, cyclical, static or moderate growth prospects and greater spreads between their bid and ask prices than securities of larger companies. Smaller capitalization companies frequently rely on narrower product lines and niche markets and may be more vulnerable to adverse business or market developments.  Securities issued by larger companies may have less growth potential and may not be able to attain the high growth rates of successful smaller companies, especially during strong economic periods.  In addition, larger companies may be less capable of responding quickly to competitive challenges and industry changes, including those resulting from improvements in technology, and may suffer sharper price declines as a result of earnings disappointments.  There is a risk that the securities issued by companies of a certain market capitalization may underperform the broader market at any given time.

Growth Stock Risk: If growth companies do not increase their earnings at a rate expected by investors, the market price of the stock may decline significantly, even if earnings show an absolute increase. Growth company stocks also typically lack the dividend yield that can cushion stock prices in market downturns.

Foreign Securities Risk: Investments in foreign (non-U.S.) securities may be riskier than investments in U.S. securities. Foreign regulatory regimes and securities markets can have less stringent investor protections and disclosure standards and less liquid trading markets than U.S. regulatory regimes and securities markets, and can experience political, social and economic developments that may affect the value of the Fund's investments in foreign securities. Foreign securities may also subject the Fund's investments to changes in currency rates. Changes in the value of foreign currencies may make the return on an investment increase or decrease, unrelated to the quality or performance of the investment itself. These risks may be greater with respect to securities of companies that conduct their business activities in emerging markets or whose securities are traded principally in emerging markets.

Past Performance

The following bar chart and table indicate some of the risks of investing in the Fund. The bar chart shows you how the Fund's calendar year performance has varied over time. Sales loads, if any, are not reflected in the bar chart. If they were, returns would be less than those shown. The average annual total returns table shows how the Fund's average annual total returns (before and after taxes) compare to those of two broad-based securities market indices. The Fund has selected the Russell 1000^® Growth Index as its primary benchmark. The Russell 1000^® Growth Index measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000^® Index companies with higher price-to-book ratios and higher forecasted growth values. The Fund has selected the Standard & Poor’s 500^® Index (“S&P 500^® Index”) as its secondary benchmark. The S&P 500^® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.

Index returns reflect no deductions for fees, expenses or taxes, except for foreign withholding taxes where applicable.

Performance data for the classes varies based on differences in their fee and expense structures. Performance data is not shown for classes with less than one calendar year of performance. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Please visit newyorklifeinvestments.com/funds for more recent performance information.

Annual Returns, Class I Shares(by calendar year 2012-2021)

Best Quarter
2020, Q2	28.27	%
Worst Quarter
2018, Q4	-15.98	%

Average Annual Total Returns (for the periods ended December 31, 2021)

After-tax returns are calculated using the highest individual federal marginal income tax rates in effect at the time of each distribution or capital gain or upon the sale of Fund shares, and do not reflect the impact of state and local taxes. In some cases, the return after taxes may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of shares at the end of the measurement period. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns are not relevant if you hold your shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns shown are for Class I shares. After-tax returns for the other share classes may vary.

Average Annual Total Returns - Prospectus Summary - MainStay Winslow Large Cap Growth Fund	Label	1 Year	5 Years	Since Inception	Inception Date
Class A		17.70%	24.07%	17.83%	Jul. 01, 1995
INVESTOR CLASS		18.11%	23.92%	17.72%	Feb. 28, 2008
Class B		18.95%	24.22%	17.52%	Apr. 01, 2005
Class C		22.40%	24.38%	17.50%	Apr. 01, 2005
Class I		24.81%	25.78%	18.79%	Apr. 01, 2005
Class I | After Taxes on Distributions		18.55%	21.75%	15.85%
Class I | After Taxes on Distributions and Sales		18.02%	20.04%	14.92%
Class R1		24.66%	25.67%	18.67%	Apr. 01, 2005
Class R2		24.42%	25.34%	18.38%	Apr. 01, 2005
Class R3		24.07%	25.02%	18.08%	Apr. 28, 2006
Class R6		24.85%	25.88%	18.95%	Jun. 17, 2013
SIMPLE CLASS		24.01%		20.86%	Aug. 31, 2020
Russell 1000® Growth Index	Russell 1000® Growth Index	27.60%	25.32%	19.79%
S&P 500® Index	S&P 500® Index	28.71%	18.47%	16.55%

[1] Class B shares are closed to all new purchases as well as additional investments by existing Class B shareholders.

[2] No initial sales charge applies on investments of $1 million or more (and certain other qualified purchases). However, a contingent deferred sales charge of 1.00% may be imposed on certain redemptions made within 18 months of the date of purchase on shares that were purchased without an initial sales charge.

[1] The management fee is as follows: 0.75% on assets up to $500 million; 0.725% on assets from $500 million to $750 million; 0.71% on assets from $750 million to $1 billion; 0.70% on assets from $1 billion to $2 billion; 0.66% on assets from $2 billion to $3 billion; 0.61% on assets from $3 billion to $7 billion; 0.585% on assets from $7 billion to $9 billion; and 0.575% on assets over $9 billion.

[2] Class B shares are closed to all new purchases as well as additional investments by existing Class B shareholders.

[3] New York Life Investments has contractually agreed to waive a portion of its management fee for the Fund so that the management fee does not exceed 0.550% on assets from $11 billion to $13 billion; and 0.525% on assets over $13 billion. This agreement will remain in effect until February 28, 2023, 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 of Trustees of the Fund.