MFS Series Trust X

03/04/2026 | Press release | Distributed by Public on 03/04/2026 08:20

Prospectus Certification by Investment Company (Form 497J)

111 Huntington Avenue, Boston, Massachusetts 02199

617-954-5000

March 4, 2026

VIA EDGAR

United States Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549

Re: MFS® Series Trust X (the "Trust") (File Nos. 33-1657 and 811-4492) on behalf of MFS® Emerging Markets Debt Local Currency Fund (the "Fund")

Ladies and Gentlemen:

Pursuant to Rule 497(j) under the Securities Act of 1933, as amended, please accept this letter on behalf of the Trust as certification that the Prospectus and the Statement of Additional Information for the Fund do not differ from those contained in Post-Effective Amendment No. 185 (the "Amendment") to the Trust's Registration Statement on Form N-1A. The Amendment was filed electronically on February 26, 2026.

Please call the undersigned at (617) 954-5655 or Jonathan Umana-Oliveira at (617) 954-5153 with any questions you may have.

Sincerely,

/s/WILLIAM B. WILSON

William B. Wilson

Assistant Vice President and Senior Counsel

MFS Series Trust X published this content on March 04, 2026, and is solely responsible for the information contained herein. Distributed via EDGAR on March 04, 2026 at 14:20 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]