# EDGAR Filing Document

**Accession Number:** 0000783740
**File Stem:** 0000912938-26-000123
**Filing Date:** 2026-1
**Character Count:** 5157
**Document Hash:** a4c9cc7fb24e434cdc652b9ebd41a582
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000912938-26-000123.hdr.sgml**: 20260127

**ACCESSION NUMBER**: 0000912938-26-000123

**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 SERIES TRUST X
- **CENTRAL INDEX KEY:** 0000783740

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** MA
- **FISCAL YEAR END:** 1130

**FILING VALUES:**
- **FORM TYPE:** 497
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 033-01657
- **FILM NUMBER:** 26562261

**BUSINESS ADDRESS:**
- **STREET 1:** 111 HUNTINGTON AVENUE
- **STREET 2:** 21ST FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02199
- **BUSINESS PHONE:** 18006372929

**MAIL ADDRESS:**
- **STREET 1:** 111 HUNTINGTON AVENUE
- **STREET 2:** 21ST FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02199

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MFS GOVERNMENT MORTGAGE FUND
- **DATE OF NAME CHANGE:** 19930408

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MFS GOVERNMENT INCOME PLUS FUND
- **DATE OF NAME CHANGE:** 19930312

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MASSACHUSETTS MFS GOVERNMENT INCOME PLUS FUND
- **DATE OF NAME CHANGE:** 19921015

## Series and Classes Contracts Data

### MFS International Large Cap Value Fund (Series ID: S000068882)

---

|  |  |  |
|:---|:---|:---|
| Class Name | Ticker Symbol | Class ID   |
| R6         | MKVHX         | C000220106 |
| R4         | MKVGX         | C000220107 |
| R3         | MKVFX         | C000220108 |
| A          | MKVBX         | C000220109 |
| R1         | MKVDX         | C000220110 |
| I          | MKVIX         | C000220111 |
| C          | MKVCX         | C000220112 |
| R2         | MKVEX         | C000220113 |

---

## Series and Classes Contracts Data

### MFS International Large Cap Value Fund (Series ID: S000068882)

| Class ID   | Class Name   | Ticker Symbol   |
|:---|:---|:---|
| C000220106 | R6           | MKVHX           |
| C000220107 | R4           | MKVGX           |
| C000220108 | R3           | MKVFX           |
| C000220109 | A            | MKVBX           |
| C000220110 | R1           | MKVDX           |
| C000220111 | I            | MKVIX           |
| C000220112 | C            | MKVCX           |
| C000220113 | R2           | MKVEX           |

?xml version='1.0' encoding='ASCII'?

![](img_1ca0be5758ff4f1.jpg)

SUPPLEMENT TO THE PROSPECTUS

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

## MFS <sup>®</sup> International Large Cap Value Fund
**Effective June 10, 2026, the first and second paragraphs in the sub-sections entitled "Principal Investment Strategies" under the main headings entitled "Summary of Key Information" and "Investment Objective, Strategies, and Risks" are restated in their entirety as follows:**

MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund's net assets in value companies with large market capitalizations. MFS defines large market capitalization issuers as issuers with market capitalizations of at least $15 billion. The market capitalization of companies considered to have large capitalizations will change over time depending on market conditions and will vary by country and region. As of December 31, 2025, the fund's average weighted market capitalization was $82.3 billion. Value companies are companies that MFS believes are undervalued compared to their perceived worth in the marketplace. MFS considers a number of factors when determining whether a company is undervalued, including whether (i) the issuer is included in an index which is representative of value companies; (ii) the issuer is classified as a value company by an independent third party financial data provider and/or (iii) the issuer exhibits the characteristics of a value company, considering metrics such as such as price-to-book ratio, price-to-earnings ratio, and dividend yield relative to the applicable equity market. Value companies tend to have stock prices that are low relative to their earnings, dividends, assets, or other financial measures.

**Effective June 10, 2026, the following sentence in the sub-section entitled "Principal Investment Strategies" under the main heading entitled "Summary of Key Information" is deleted in its entirety:**

MFS focuses on investing the fund's assets in the stocks of companies it believes are undervalued compared to their perceived worth (value companies).

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

**Effective June 10, 2026, the following paragraph in the sub-section entitled "Principal Investment Strategies" under the main heading entitled "Investment Objective, Strategies, and Risks" is deleted in its entirety:**

MFS focuses on investing the fund's assets in the stocks of companies that it believes are undervalued compared to their perceived worth (value companies). Value companies tend to have stock prices that are low relative to their earnings, dividends, assets, or other financial measures.

MKV-SUP-I-012726

------