# EDGAR Filing Document

**Accession Number:** 0001469192
**File Stem:** 0001741773-23-000938
**Filing Date:** 2023-3
**Character Count:** 4135
**Document Hash:** 53cbb8a0f43ed9617befc14f08017dec
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001741773-23-000938.hdr.sgml**: 20230323

**ACCESSION NUMBER**: 0001741773-23-000938

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 15

**FILED AS OF DATE**: 20230323

**DATE AS OF CHANGE**: 20230323

**EFFECTIVENESS DATE**: 20230323

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MAINSTAY FUNDS TRUST
- **CENTRAL INDEX KEY:** 0001469192
- **IRS NUMBER:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1031

**FILING VALUES:**
- **FORM TYPE:** 497
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-160918
- **FILM NUMBER:** 23754666

**BUSINESS ADDRESS:**
- **STREET 1:** 51 MADISON AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10010
- **BUSINESS PHONE:** 212 576 7000

**MAIL ADDRESS:**
- **STREET 1:** 51 MADISON AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10010

## Series and Classes Contracts Data

### MainStay Floating Rate Fund (Series ID: S000028529)

---

|  |  |  |
|:---|:---|:---|
| Class Name     | Ticker Symbol | Class ID   |
| Investor Class | MXFNX         | C000087333 |
| Class A        | MXFAX         | C000087334 |
| Class B        | MXFBX         | C000087335 |
| Class C        | MXFCX         | C000087336 |
| Class I        | MXFIX         | C000087337 |
| Class R3       | MXFHX         | C000166839 |
| Class R6       | MXFEX         | C000185929 |
| SIMPLE Class   | MXFMX         | C000221660 |

---

## Series and Classes Contracts Data

### MainStay Floating Rate Fund (Series ID: S000028529)

| Class ID   | Class Name     | Ticker Symbol   |
|:---|:---|:---|
| C000087333 | Investor Class | MXFNX           |
| C000087334 | Class A        | MXFAX           |
| C000087335 | Class B        | MXFBX           |
| C000087336 | Class C        | MXFCX           |
| C000087337 | Class I        | MXFIX           |
| C000166839 | Class R3       | MXFHX           |
| C000185929 | Class R6       | MXFEX           |
| C000221660 | SIMPLE Class   | MXFMX           |

?xml version="1.0"?

#### MAINSTAY FUNDS TRUST

#### MainStay Floating Rate Fund

#### (the "Fund")
Supplement dated March 23, 2023 ("Supplement") to the

Prospectus dated February 28, 2023, as supplemented

*Capitalized terms and certain other terms used in this Supplement, unless otherwise defined in this Supplement, have the meanings assigned to them in the Prospectus.* 

The table and footnotes in the section entitled "**Average Annual Total Returns (**for the periods ended December 31, 2022)" are deleted and replaced with the following to reflect revised figures provided by the Fund's primary benchmark index provider:

#### Past Performance

#### Average Annual Total Returns (for the periods ended December 31, 2022)

---

| | | | | |
|:---|:---|:---|:---|:---|
| | <br>Inception<br>| <br>&nbsp;&nbsp;&nbsp;&nbsp; 1 Year<br> | <br>5 Years<br> | 10 Years or<br>Since<br>Inception |
| Return Before Taxes |  |  |  |  |
| &nbsp;&nbsp;&nbsp;Class I | 5/3/2004 | -1.06% | 2.54% | 2.99% |
| Return After Taxes on Distributions |  |  |  |  |
| &nbsp;&nbsp;&nbsp;Class I |  | -2.93% | 0.83% | 1.27% |
| Return After Taxes on Distributions and Sale of Fund Shares |  |  |  |  |
| &nbsp;&nbsp;&nbsp;Class I |  | -0.63% | 1.22% | 1.52% |
| Return Before Taxes |  |  |  |  |
| &nbsp;&nbsp;&nbsp;Class A | 5/3/2004 | -4.27% | 1.66% | 2.44% |
| &nbsp;&nbsp;&nbsp;Investor Class | 2/28/2008 | -3.85% | 1.63% | 2.41% |
| &nbsp;&nbsp;&nbsp;Class B | 5/3/2004 | -4.95% | 1.51% | 1.96% |
| &nbsp;&nbsp;&nbsp;Class C | 5/3/2004 | -3.18% | 1.49% | 1.95% |
| &nbsp;&nbsp;&nbsp;Class R3 | 2/29/2016 | -1.76% | 1.93% | 3.17% |
| &nbsp;&nbsp;&nbsp;Class R6 | 2/28/2019 | -1.06% | N/A | 2.47% |
| &nbsp;&nbsp;&nbsp;SIMPLE Class | 8/31/2020 | -1.74% | N/A | 2.00% |
| Morningstar LSTA US Leveraged Loan Index<sup>1</sup> | Morningstar LSTA US Leveraged Loan Index<sup>1</sup> | -0.77% | 3.27% | 3.65% |

---

1. The Morningstar LSTA US Leveraged Loan Index is a broad index designed to reflect the performance of U.S. dollar facilities in the leveraged loan market.

#### PLEASE RETAIN THIS SUPPLEMENT FOR YOUR FUTURE REFERENCE
MS16bb-03/23

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