Total

MainStay Floating Rate Fund

MainStay Floating Rate Fund

Investment Objective

The Fund seeks high current income.

Fees and Expenses of the Fund

The table below describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may be required to pay a commission or other transaction charge to your financial intermediary for effecting transactions in a class of shares of the Fund that has no initial sales charge, contingent deferred sales charge, or other asset-based fee for sales or distribution, such as Class I or Class R6 shares. These commissions are not reflected in the fee and expense table or expense 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 130 of the Prospectus and Appendix A – Intermediary-Specific Sales Charge Waivers and Discounts, and in the "Alternative Sales Arrangements" section on page 123 of the Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - MainStay Floating Rate Fund	Class A		Investor Class		Class B	[1]	Class C	Class I	Class R3	Class R6
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	3.00%		3.00%		none		none	none	none	none
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds)	none	[2]	none	[2]	3.00%		1.00%	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 - MainStay Floating Rate Fund		Class A	Investor Class	Class B	[2]	Class C	Class I	Class R3	Class R6
Management Fees (as an annual percentage of the Fund's average daily net assets)	[1]	0.59%	0.59%	0.59%		0.59%	0.59%	0.59%	0.59%
Distribution and/or Service (12b-1) Fees		0.25%	0.25%	1.00%		1.00%	none	0.50%	none
Other Expenses		0.25%	0.24%	0.24%		0.24%	0.25%	0.35%	0.05%
Total Annual Fund Operating Expenses		1.09%	1.08%	1.83%		1.83%	0.84%	1.44%	0.64%

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 also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The Example also reflects Class B shares converting into Investor Class shares in year 4; fees could be lower if you are eligible to convert to Class A shares instead. 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 - MainStay Floating Rate Fund - USD ($)	Class A	Investor Class	Class B	Class C	Class I	Class R3	Class R6
1 Year	$ 408	$ 407	$ 486	$ 286	$ 86	$ 147	$ 65
3 Years	636	633	776	576	268	456	205
5 Years	883	878	904	990	466	787	357
10 Years	$ 1,589	$ 1,578	$ 1,606	$ 2,148	$ 1,037	$ 1,724	$ 798

Assuming no redemption

Expense Example No Redemption - MainStay Floating Rate Fund - USD ($)	Class B	Class C
1 Year	$ 186	$ 186
3 Years	576	576
5 Years	904	990
10 Years	$ 1,606	$ 2,148

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 19% of the average value of its portfolio.

Principal Investment Strategies

The Fund, under normal circumstances, invests at least 80% of its assets (net assets plus any borrowings for investment purposes) in a portfolio of floating rate loans and other floating rate debt securities. The Fund may also purchase fixed-income and variable rate debt securities and money market securities or instruments. When NYL Investors LLC, the Fund's Subadvisor, believes that market or economic conditions are unfavorable to investors, up to 100% of the Fund's assets may be invested in money market or short-term debt securities. The Subadvisor may also invest in these types of securities or hold a higher than ordinary level of cash, while looking for suitable investment opportunities or to maintain an appropriate level of liquidity.

The Fund may invest up to 25% of its total assets in foreign securities which are generally U.S. dollar-denominated loans and other debt securities issued by one or more non-U.S. borrower(s) without a U.S. domiciled co-borrower.

Investment Process: The Subadvisor seeks to identify investment opportunities based on the financial condition and competitiveness of individual companies. The Subadvisor seeks to invest in companies with a high margin of safety that are leaders in industries with high barriers to entry. The Subadvisor prefers companies with positive free cash flow, solid asset coverage and management teams with strong track records. In virtually every phase of the investment process, the Subadvisor attempts to control risk and limit defaults.

Floating rate loans may offer a favorable yield spread over other short-term debt alternatives. Historically, floating rate loans have displayed little correlation to the movements of U.S. common stocks, high-grade bonds and U.S. government securities. Securities that are rated below investment grade by a nationally recognized statistical rating organization (“NRSRO”) (such as securities rated lower than BBB- and Baa3), commonly referred to as “high-yield securities” or “junk bonds.” Floating rate loans are speculative investments and are usually rated below investment grade by an NRSRO. They typically have less credit risk and historically have had lower default rates than junk bonds. These loans are typically the most senior source of capital in a borrower's capital structure and usually have certain of the borrower's assets pledged as collateral. Floating rate loans feature rates that reset regularly, maintaining a fixed spread over the London InterBank Offered Rate, the prime rates of large money-center banks or other reference rates. The interest rates for floating rate loans typically reset quarterly, although rates on some loans may adjust at other intervals. Floating rate loans mature, on average, in five to seven years, but loan maturity can be as long as nine years.

The Subadvisor may reduce or eliminate the Fund's position in a holding if it no longer believes the holding will contribute to meeting the investment objective of the Fund. In considering whether to sell a holding, the Subadvisor may evaluate, among other things, meaningful changes in the issuer's financial condition and competitiveness. The Subadvisor continually evaluates market factors and comparative metrics to determine relative value.

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. In addition, the Fund may not achieve its investment objective, including during periods in which the Subadvisor takes temporary positions in response to unusual or adverse market, economic or political conditions, or other unusual or abnormal circumstances.

Yield Risk: There can be no guarantee that the Fund will achieve or maintain any particular level of yield.

Debt Securities Risk: The risks of investing in debt or fixed-income securities include (without limitation): (i) credit risk, e.g., the issuer or guarantor of a debt security may be unable or unwilling (or be perceived as unable or unwilling) to make timely principal and/or interest payments or otherwise honor its obligations, or changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may affect the value of the Fund’s investments; (ii) maturity risk, e.g., a debt security with a longer maturity may fluctuate in value more than one with a shorter maturity; (iii) market risk, e.g., low demand for debt securities may negatively impact their price; (iv) interest rate risk, e.g., when interest rates go up, the value of a debt security generally goes down, and when interest rates go down, the value of a debt security generally goes up (long-term debt securities are generally more susceptible to interest rate risk than short-term debt securities); and (v) call or prepayment risk, e.g., during a period of falling interest rates, the issuer may redeem a security by repaying it early, which may reduce the Fund’s income if the proceeds are reinvested at lower interest rates.

Interest rate risk is the risk that the value of the Fund’s investments in fixed income or debt securities will change because of changes in interest rates. There is a risk that interest rates across the financial system may change, possibly significantly and/or rapidly. Changes in interest rates or a lack of market participants may lead to decreased liquidity and increased volatility in the fixed-income or debt markets, making it more difficult for the Fund to sell its fixed-income or debt holdings. Decreased liquidity in the fixed-income or debt markets also may make it more difficult to value some or all of the Fund’s fixed-income or debt holdings. For most fixed-income investments, when market interest rates fall, prices of fixed-rate debt securities rise. However, when market interest rates fall, prices of certain variable and fixed-rate debt securities may be adversely affected (i.e., falling interest rates bring the possibility of prepayment risk, as an instrument may be redeemed before maturity).

Not all U.S. government debt securities are guaranteed by the U.S. government—some are backed only by the issuing agency, which must rely on its own resources to repay the debt. The Fund's yield will fluctuate with changes in short-term interest rates.

Floating Rate Loans Risk: The floating rate loans in which the Fund invests are usually rated below investment grade, or if unrated, determined by the Subadvisor to be of comparable quality (commonly referred to as "junk bonds") and are generally considered speculative because they present a greater risk of loss, including default, than higher quality debt instruments. Moreover, such investments may, under certain circumstances, be particularly susceptible to liquidity and valuation risks. Although certain floating rate loans are collateralized, there is no guarantee that the value of the collateral will be sufficient or available to satisfy the borrower’s obligation. In times of unusual or adverse market, economic or political conditions, floating rate loans may experience higher than normal default rates. In the event of a recession or serious credit event, among other eventualities, the value of the Fund's investments in floating rate loans are more likely to decline. The secondary market for floating rate loans is limited and, thus, the Fund’s ability to sell or realize the full value of its investment in these loans to reinvest sale proceeds or to meet redemption obligations may be impaired. In addition, floating rate loans generally are subject to extended settlement periods that may be longer than seven days. As a result, the Fund may be adversely affected by selling other investments at an unfavorable time and/or under unfavorable conditions or engaging in borrowing transactions, such as borrowing against its credit facility, to raise cash to meet redemption obligations or pursue other investment opportunities.

In certain circumstances, floating rate loans may not be deemed to be securities. As a result, the Fund may not have the protection of the anti-fraud provisions of the federal securities laws. In such cases, the Fund generally must rely on the contractual provisions in the loan agreement and common-law fraud protections under applicable state law.

Floating rate loans and other similar debt obligations that lack financial maintenance covenants or possess fewer or contingent financial maintenance covenants and other financial protections for lenders and investors (sometimes referred to as “covenant-lite” loans or obligations) are generally subject to more risk than investments that contain traditional financial maintenance covenants and financial reporting requirements.

The terms of many floating rate loans and other instruments are tied to the London Interbank Offered Rate (“LIBOR”), which functions as a reference rate or benchmark. It is anticipated that LIBOR will be discontinued at the end of 2021, which may cause increased volatility and illiquidity in the markets for instruments with terms tied to LIBOR or other adverse consequences for these instruments. These events may adversely affect the Fund and its investments in such instruments.

Liquidity and Valuation Risk: The Fund’s investments may be illiquid at the time of purchase or liquid at the time of purchase and subsequently become illiquid due to, among other things, events relating to the issuer of the securities, market events, operational issues, economic conditions, investor perceptions or lack of market participants. The lack of an active trading market may make it difficult to sell or obtain an accurate price for a security. If market conditions or issuer specific developments make it difficult to value securities, the Fund may value these securities using more subjective methods, such as fair value pricing. In such cases, the value determined for a security could be different than the value realized upon such security's sale. As a result, an investor could pay more than the market value when buying Fund shares or receive less than the market value when selling Fund shares. This could affect the proceeds of any redemption or the number of shares an investor receives upon purchase.

The Fund is subject to the risk that it could not meet redemption requests within the allowable time period without significant dilution of remaining investors' interests in the Fund. To meet redemption requests or to raise cash to pursue other investment opportunities, the Fund may be forced to sell securities at an unfavorable time and/or under unfavorable conditions, which may adversely affect the Fund.

Loan Participation Interest Risk: There may not be a readily available market for loan participation interests, which in some cases could result in the Fund disposing of such interests at a substantial discount from face value or holding such interests until maturity. In addition, the Fund may be exposed to the credit risk of the underlying corporate borrower as well as the lending institution or other participant from whom the Fund purchased the loan participation interests. The Fund may not always have direct recourse against a borrower if the borrower fails to pay scheduled principal and/or interest and may be subject to greater delays, expenses and risks than if the Fund had purchased a direct obligation of the borrower. Substantial increases in interest rates may cause an increase in loan obligation defaults.

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.

High-Yield Securities Risk: Investments in high-yield securities or non-investment grade securities (commonly referred to as "junk bonds") are considered speculative because investments in such securities present a greater risk of loss than investments in higher quality securities. Such securities may, under certain circumstances, be less liquid than higher rated securities. These securities pay investors a premium (a high interest rate or yield) because of the potential illiquidity and increased risk of loss. These securities can also be subject to greater price volatility. In times of unusual or adverse market, economic or political conditions, these securities may experience higher than normal default rates.

Money Market/Short-Term Securities Risk: To the extent the Fund holds cash or invests in money market or short-term securities, the Fund may be less likely to achieve its investment objective. In addition, it is possible that the Fund's investments in these instruments could lose money.

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 S&P/LSTA Leveraged Loan Indexas its primary benchmark. The S&P/LSTA Leveraged Loan Index is a broad index designed to reflect the performance of U.S. dollar facilities in the leveraged loan market. The Fund has selected the Credit Suisse Leveraged Loan Index as its secondary benchmark. The Credit Suisse Leveraged Loan Index represents tradable, senior-secured, U.S. dollar-denominated non-investment-grade loans.

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 nylinvestments.com/funds for more recent performance information.

Annual Returns, Class I Shares (by calendar year 2010-2019)

Best Quarter
1Q/19	4.01	%
Worst Quarter
4Q/18	-3.84	%

Average Annual Total Returns (for the periods ended December 31, 2019)

Average Annual Returns - MainStay Floating Rate Fund	1 Year	5 Years or Since Inception	10 Years	Inception Date
Class I	8.44%	4.04%	4.30%	May 03, 2004
Class A	4.92%	3.17%	3.72%	May 03, 2004
Investor Class	4.93%	3.17%	3.69%	Feb. 28, 2008
Class B	4.37%	3.02%	3.24%	May 03, 2004
Class C	6.37%	3.00%	3.24%	May 03, 2004
Class R3	7.78%	4.87%		Feb. 29, 2016
After Taxes on Distributions | Class I	6.30%	2.20%	2.59%
After Taxes on Distributions and Sale of Fund Shares | Class I	4.96%	2.26%	2.58%
S&P/LSTA Leveraged Loan Index (reflects no deductions for fees, expenses, or taxes)	8.64%	4.45%	5.01%
Credit Suisse Leveraged Loan Index (reflects no deductions for fees, expenses, or taxes)	8.17%	4.54%	5.18%

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.

[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 $250,000 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: 0.60% on assets up to $1 billion; 0.575% on assets from $1 billion to $3 billion; and 0.565% on assets over $3 billion.

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