SUPPLEMENT TO THE PROSPECTUS

Supplement dated September 24, 2026, to the Prospectus dated January 28, 2026.

MFS^® Blended Research^® Core Equity Fund

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

Effective October 31, 2026, Nathan Bryant will join Matt Krummell as co-lead portfolio manager of the fund.

UNE-SUP-I-092426

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