MFS Series Trust X

04/20/2026 | Press release | Distributed by Public on 04/20/2026 10:09

Prospectus by Investment Company (Form 497)

SUPPLEMENT TO THE PROSPECTUS

Supplement dated April 20, 2026, to the Prospectus dated September 26, 2025.

MFS® Blended Research® Growth Equity Fund

Effective immediately, the sub-section entitled "Portfolio Manager(s)" under the main heading entitled "Summary of Key Information" is restated in its entirety as follows:

Portfolio Manager(s)

Portfolio Manager

Since

Title

Matt Krummell

2015

Investment Officer of MFS

Nathan Bryant

January 2026

Investment Officer of MFS

Jonathan Sage

2015

Investment Officer of MFS

Jed Stocks

2015

Investment Officer of MFS

Jenney Zhang

January 2026

Investment Officer of MFS

Matt Krummell has announced his intention to retire effective April 7, 2027, and he will no longer be a portfolio manager of the fund as of that date.

Effective immediately, the sub-section entitled "Portfolio Manager(s)" under the main heading entitled "Management of the Fund" is restated in its entirety as follows:

Portfolio Manager(s)

Information regarding the portfolio manager(s) of the fund is set forth below. Further information regarding the portfolio manager(s), including other accounts managed, compensation, ownership of fund shares, and possible conflicts of interest, is available in the fund's SAI.

Portfolio Manager

Primary Role

Five Year History

Matt Krummell

Lead Portfolio Manager

Employed in the investment area of MFS since 2001

Nathan Bryant

Portfolio Manager

Employed in the investment area of MFS since 2015

Jonathan Sage

Portfolio Manager

Employed in the investment area of MFS since 2000

Jed Stocks

Portfolio Manager

Employed in the investment area of MFS since 2001

Jenney Zhang

Portfolio Manager

Employed in the investment area of MFS since 2011

Matt Krummell has announced his intention to retire effective April 7, 2027, and he will no longer be a portfolio manager of the fund as of that date.

BRW-SUP-I-042026

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