MFS Series Trust X

10/15/2026 | Press release | Distributed by Public on 10/15/2026 06:43

Prospectus by Investment Company (Form 497)

SUPPLEMENT TO THE PROSPECTUS

Supplement dated October 15, 2026, to the Prospectus dated September 28, 2026.

MFS® International Value Fund

(Formerly, MFS® International Large Cap Value Fund)

Effective December 31, 2026, the following is added to the table in the sub-section entitled "Portfolio Manager(s)" under the main heading entitled "Summary of Key Information":

Portfolio Manager

Since

Title

David Falco

December 2026

MFS Co-Chief Investment Officer-Equity

Effective December 31, 2026, the following is added to the table in the sub-section entitled "Portfolio Manager(s)" under the main heading entitled "Management of the Fund":

Portfolio Manager

Primary Role

Five Year History

David Falco

Portfolio Manager

Employed in the investment area of MFS since 2011

MKV-SUP-I-101526

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