MainStay MacKay Strategic Bond Fund  Class A: MASAX | Class C: MSICX | Class I: MSDIX | Class INV: MSYDX | Class R6: MSYEX

BEFORE YOU INVEST

At a meeting held on December 9-10, 2020, the Board of Trustees of The MainStay Funds considered and approved the following change to the Fund’s name, which took effect on February 28, 2021: Current Name: MainStay MacKay Unconstrained Bond Fund; New Name MainStay MacKay Strategic Bond Fund.


Before considering an investment in the Fund, you should understand that you could lose money.


Investing in below investment grade securities may carry a greater risk of nonpayment of interest or principal than higher-rated bonds.


Foreign securities are subject to interest rate, currency exchange rate, economic, and political risks. These risks may be greater for emerging markets.


Short positions pose a risk because they lose value as a security's price increases; therefore, the loss on a short sale is theoretically unlimited. As a result, these funds may not be suitable for all investors.


The use of leverage may increase the Fund's exposure to long equity positions and make any change in the Fund's NAV greater than it would be without the use of leverage. This could result in increased volatility of returns.


Issuers of convertible securities may not be as financially strong as those issuing securities with higher credit ratings and are more vulnerable to economic changes.


The Fund may invest in derivatives, which may increase the volatility of the Fund's NAV and may result in a loss to the Fund.


The principal risk of mortgage dollar rolls is that the security the Fund receives at the end of the transaction may be worth less than the security the Fund sold to the same counterparty at the beginning of the transaction.


The principal risk of mortgage-related and asset-backed securities is that the underlying debt may be prepaid ahead of schedule, if interest rates fall, thereby reducing the value of the fund’s investment.  If interest rates rise, less of the debt may be prepaid and the fund may lose money. 


Unconstrained bond funds generally have higher fees than the standard core bond funds.


Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the investment-grade, U.S. dollar denominated, fixed-rate taxable bond market, including Treasuries, 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.


ICE BofA Merrill Lynch U.S. Dollar 3-Month Deposit Offered Rate Constant Maturity Index represents the London InterBank Offered Rate ("LIBOR") with a constant 3-month average maturity. LIBOR is a composite of interest rates at which banks borrow from one another in the London market, and it is a widely used benchmark for short-term interest rates.


An investment cannot be made directly into an index. 


Sharpe Ratio shown is calculated for the past 36-month period by dividing annualized excess returns by annualized standard deviation.

Beta is a measure of historical volatility relative to an appropriate index (benchmark) based on its investment objective. A beta greater than 1.00 indicates volatility greater than the benchmark's. 

R-Squared measures the percentage of a fund's movements that result from movements in the index.

Effective Maturity is the average time to maturity of debt securities held in the portfolio, taking into consideration the possibility that the issuer may call the bond before its maturity date.

Effective Duration provides a measure of a fund's interest-rate sensitivity. The longer a fund's duration, the more sensitive the fund is to shifts in interest rates.

The Morningstar Rating™ for funds, or "star rating", is calculated for managed products (including mutual funds, variable annuity and variable life subaccounts, exchange-traded funds, closed-end funds, and separate accounts) with at least a three-year history. Exchange-traded funds and open-ended mutual funds are considered a single population for comparative purposes. It is calculated based on a Morningstar Risk-Adjusted Return measure that accounts for variation in a managed product's monthly excess performance, placing more emphasis on downward variations and rewarding consistent performance (this does not include the effects of sales charges, loads, and redemption fees). The top 10% of products in each product category receive 5stars, the next 22.5% receive 4 stars, the next 35% receive 3 stars, the next 22.5% receive 2 stars, and the bottom 10% receive 1 star. The Overall Morningstar Rating for a managed product is derived from a weighted average of the performance figures associated with its three-, five-, and 10-year (if applicable) Morningstar Rating metrics. The weights are: 100% three-year rating for 36-59 months of total returns, 60% five-year rating/40% three-year rating for 60-119 months of total returns, and 50% 10-year rating/30% five-year rating/20% three-year rating for 120 or more months of total returns. While the 10-year overall star rating formula seems to give the most weight to the 10-year period, the most recent three-year period actually has the greatest impact because it is included in all three rating periods.