MFS Series Trust III

10/30/2026 | Press release | Distributed by Public on 10/30/2026 14:51

Prospectus by Investment Company (Form 497)

SUPPLEMENT TO THE STATEMENT OF ADDITIONAL INFORMATION

The date of this supplement is October 30, 2026.

For the MFS® Funds listed below:

MFS® HIGH INCOME FUND

MFS® GLOBAL HIGH YIELD FUND

MFS® HIGH YIELD POOLED PORTFOLIO

MFS® MUNICIPAL HIGH INCOME FUND

After October 30, 2026, MFS High Yield Pooled Portfolio will be terminated. After October 30, 2026, all references and information related to MFS High Yield Pooled Portfolio are hereby deleted in their entirety.

MAY-SAI-COMBINED-SUP-I-103026

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MFS Series Trust III published this content on October 30, 2026, and is solely responsible for the information contained herein. Distributed via EDGAR on October 30, 2026 at 20:51 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 If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]