# EDGAR Filing Document

**Accession Number:** 0000783740
**File Stem:** 0000912938-26-000339
**Filing Date:** 2026-3
**Character Count:** 13926
**Document Hash:** 8cdbe720dbd15c7b4f15283c478d5130
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000912938-26-000339.hdr.sgml**: 20260331

**ACCESSION NUMBER**: 0000912938-26-000339

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 17

**FILED AS OF DATE**: 20260331

**DATE AS OF CHANGE**: 20260331

**EFFECTIVENESS DATE**: 20260331

**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:** 26821622

**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_26dab30495fa4f1.jpg)

SUPPLEMENT TO THE PROSPECTUS

*Supplement dated April 1, 2026, to the Prospectus dated September 26, 2025.*

## MFS <sup>®</sup> International Large Cap Value Fund
**Effective immediately, the sub-sections entitled "Fees and Expenses" and "Example" under the main heading entitled "Summary of Key Information" are restated in their entirety as follows:**

#### Fees and Expenses
This table describes the fees and expenses that you may pay when you buy, hold, and sell shares of the fund. **Investors may also pay commissions or other fees to their financial intermediaries when they buy, hold, and sell shares of the fund, which are not reflected below.** Expenses have been adjusted to reflect fee arrangements that are effective April 1, 2026.

You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS funds. More information about these and other waivers and reductions is available from your financial intermediary and in "Sales Charges and Waivers and Reductions" on page 10 and "Appendix A – Waivers and Reductions of Sales Charges" on page A-1 of the fund's prospectus.

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| **Shareholder Fees (fees paid directly from your investment):** | **Shareholder Fees (fees paid directly from your investment):** | **Shareholder Fees (fees paid directly from your investment):** | **Shareholder Fees (fees paid directly from your investment):** | **Shareholder Fees (fees paid directly from your investment):** | **Shareholder Fees (fees paid directly from your investment):** | **Shareholder Fees (fees paid directly from your investment):** | **Shareholder Fees (fees paid directly from your investment):** | **Shareholder Fees (fees paid directly from your investment):** |
| **Share Class** | **A** | **C** | **I** | **R1** | **R2** | **R3** | **R4** | **R6** |
| **Maximum Sales Charge (Load) <br>Imposed on Purchases (as a percentage of offering price)** | 5.75% |  |  |  |  |  |  |  |
| **Maximum Deferred Sales Charge (Load) <br>(as a percentage of original purchase price or redemption proceeds, whichever is less)** | 1.00%<sup>#</sup> | 1.00% |  |  |  |  |  |  |

---

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** | **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** | **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** | **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** | **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** | **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** | **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** | **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** | **Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):** |
| **Share Class** | **A** | **C** | **I** | **R1** | **R2** | **R3** | **R4** | **R6** |
| Management Fee | 0.68% | 0.68% | 0.68% | 0.68% | 0.68% | 0.68% | 0.68% | 0.68% |
| Distribution and/or Service (12b-1) Fees | 0.25% | 1.00% |  | 1.00% | 0.50% | 0.25% |  |  |
| Other Expenses | <u>0.06%</u> | <u>0.06%</u> | <u>0.06%</u> | <u>0.06%</u> | <u>0.06%</u> | <u>0.06%</u> | <u>0.06%</u> | <u>0.03%</u> |
| Total Annual Fund Operating Expenses | 0.99% | 1.74% | 0.74% | 1.74% | 1.24% | 0.99% | 0.74% | 0.71% |
| Fee Reductions and/or Expense Reimbursements<sup>1</sup> | <u>(0.03)%</u> | <u>(0.03)%</u> | <u>(0.03)%</u> | <u>(0.03)%</u> | <u>(0.03)%</u> | <u>(0.03)%</u> | <u>(0.03)%</u> | <u>(0.04)%</u> |
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | 0.96% | 1.71% | 0.71% | 1.71% | 1.21% | 0.96% | 0.71% | 0.67% |

---

# This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.

1 Massachusetts Financial Services Company (MFS) has agreed in writing to waive at least 0.01% of the fund's management fee as part of an agreement pursuant to which MFS has agreed to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund's Board of Trustees. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least September 30, 2027. MFS has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, certain tax reclaim recovery expenses (including contingency fees and closing agreement expenses), and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Total Annual Fund Operating Expenses" do not exceed 0.96% of the class' average daily net assets annually for each of Class A and Class R3 shares, 1.71% of the class' average daily net assets annually for each of Class C and Class R1 shares, 0.71% of the class' average daily net assets annually for each of Class I and Class R4 shares, 1.21% of the class' average daily net assets annually for Class R2 shares, and 0.67% of the class' average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least September 30, 2027.

MKV-SUP-I-040126

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MFS International Large Cap Value Fund

#### Example
This 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 and you redeem your shares at the end of the time periods (unless otherwise indicated); your investment has a 5% return each year; and the fund's operating expenses remain the same.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

---

| | | | | |
|:---|:---|:---|:---|:---|
|  | **1 YEAR** | **3 YEARS** | **5 YEARS** | **10 YEARS** |
| **Class A Shares** | $667  | $868  | $1087  | $1715  |
| **Class C Shares assuming<sup>1</sup>** |  |  |  |  |
| &nbsp;&nbsp;&nbsp;redemption at end of period | $274  | $544  | $940  | $1850  |
| &nbsp;&nbsp;&nbsp;no redemption at end of period | $174  | $544  | $940  | $1850  |
| **Class I Shares** | $73  | $232  | $407  | $915  |
| **Class R1 Shares** | $174  | $544  | $940  | $2048  |
| **Class R2 Shares** | $123  | $389  | $677  | $1496  |
| **Class R3 Shares** | $98  | $311  | $543  | $1209  |
| **Class R4 Shares** | $73  | $232  | $407  | $915  |
| **Class R6 Shares** | $68  | $221  | $389  | $877  |

---

1 Shares automatically convert to Class A shares approximately eight years after purchase; therefore, the expense examples reflect Class A share expenses after eight years.

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

**Effective immediately, the third, fourth, and fifth paragraphs in the sub-section entitled "Investment Adviser" under the main heading entitled "Management of the Fund" are restated in their entirety with the following four paragraphs:**

Effective April 1, 2026, the management fee set forth in the Investment Advisory Agreement is 0.75% of the fund's average daily net assets annually up to $1 billion; 0.70% of the fund's average daily net assets annually in excess of $1 billion and up to $2.5 billion; 0.65% of the fund's average daily net assets annually in excess of $2.5 billion and up to $10 billion; 0.62% of the fund's average daily net assets annually in excess of $10 billion and up to $20 billion; and 0.60% of the fund's average daily net assets annually in excess of $20 billion.

For the period from June 1, 2024, to March 31, 2026, the management fee set forth in the Investment Advisory Agreement was 0.75% of the fund's average daily net assets annually up to $2.5 billion; 0.70% of the fund's average daily net assets annually in excess of $2.5 billion and up to $5 billion; 0.65% of the fund's average daily net assets annually in excess of $5 billion and up to $10 billion; 0.62% of the fund's average daily net assets annually in excess of $10 billion and up to $20 billion; and 0.60% of the fund's average daily net assets annually in excess of $20 billion.

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund's Board of Trustees. MFS has agreed in writing to waive at least 0.01% of its management fee as part of this agreement. The agreement to waive at least 0.01% of the management fee will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least September 30, 2027. For the fiscal year ended May 31, 2025, this management fee reduction amounted to 0.01% of the fund's average daily net assets.

MFS has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, certain tax reclaim recovery expenses (including contingency fees and closing agreement expenses), and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Total Annual Fund Operating Expenses" do not exceed 0.96% of the class' average daily net assets annually for each of Class A and Class R3 shares, 1.71% of the class' average daily net assets annually for each of Class C and Class R1 shares, 0.71% of the class' average daily net assets annually for each of Class I and Class R4 shares, 1.21% of the class' average daily net assets annually for Class R2 shares, and 0.67% of the class' average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least September 30, 2027.

**Effective immediately, the sub-section entitled "Fees and Expenses" under the heading entitled "Additional Information on Fees and Expenses and Performance" under the main heading entitled "Other Information" is restated in its entirety as follows:**

The annual fund operating expenses shown in "Fees and Expenses" are based on annualized expenses reported during the fund's most recently completed fiscal year expressed as a percentage of a class' average net assets during the period. Expenses have been adjusted to reflect fee arrangements that are effective April 1, 2026. Annual fund operating expenses have not been adjusted to reflect the fund's current asset size. In general, annual fund operating expenses, expressed as a percentage of a class' average net assets, increase as the fund's assets decrease. Annual fund operating expenses will likely vary from year to year.

MKV-SUP-I-040126

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