# EDGAR Filing Document

**Accession Number:** 0002018846
**File Stem:** 0000912938-26-000105
**Filing Date:** 2026-1
**Character Count:** 2931
**Document Hash:** cdabdfcc1e0b0db9b4460243875ea531
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000912938-26-000105.hdr.sgml**: 20260127

**ACCESSION NUMBER**: 0000912938-26-000105

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 18

**FILED AS OF DATE**: 20260127

**DATE AS OF CHANGE**: 20260127

**EFFECTIVENESS DATE**: 20260127

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MFS Active Exchange Traded Funds Trust
- **CENTRAL INDEX KEY:** 0002018846

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** MA
- **FISCAL YEAR END:** 0228

**FILING VALUES:**
- **FORM TYPE:** 497
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-278691
- **FILM NUMBER:** 26562207

**BUSINESS ADDRESS:**
- **STREET 1:** 111 HUNTINGTON AVENUE
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02199
- **BUSINESS PHONE:** 617-954-5000

**MAIL ADDRESS:**
- **STREET 1:** 111 HUNTINGTON AVENUE
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02199

## Series and Classes Contracts Data

### MFS Active Mid Cap ETF (Series ID: S000094824)

---

|  |  |  |
|:---|:---|:---|
| Class Name             | Ticker Symbol | Class ID   |
| MFS Active Mid Cap ETF | MMID          | C000263368 |

---

## Series and Classes Contracts Data

### MFS Active Mid Cap ETF (Series ID: S000094824)

| Class ID   | Class Name             | Ticker Symbol   |
|:---|:---|:---|
| C000263368 | MFS Active Mid Cap ETF | MMID            |

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![](img_ce7ea8eed4f04f1.jpg)

SUPPLEMENT TO THE PROSPECTUS

*Supplement dated January 27, 2026, to the Prospectus dated August 26, 2025.*

## MFS <sup>®</sup> Active Mid Cap ETF
**Effective June 10, 2026, the first paragraph in the sub-sections entitled "Principal Investment Strategies" under the main headings entitled "Summary of Key Information" and "Investment Objective, Strategies, and Risks" is restated in its entirety with the following paragraph:**

MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund's net assets in issuers with medium market capitalizations. MFS defines medium market capitalization companies as issuers that (i) have market capitalizations within the capitalization range of the Russell Midcap<sup>®</sup> Index over the past 12 months based on the current composition of the index and/or are (ii) classified as a medium capitalization company by an independent third party financial data provider. The market capitalization range of companies considered to have medium capitalizations based on the above criteria will change over time depending on market conditions. For illustrative purposes, as of December 31, 2025, the range of the market capitalizations of the issuers in the Russell Midcap<sup>®</sup> Index was between approximately $1.3 billion and $101.9 billion, and the fund's average weighted market capitalization as of that date was $21.9 billion.

**-- End of Supplement Data --**

ECM-SUP-I-012726

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