Summary Prospectus by Investment Company (Form 497K)

MASSMUTUAL FUNDS

MassMutual Clinton Municipal Fund

Supplement dated December 4, 2025 to the

Prospectus dated February 1, 2025, as Revised on February 5, 2025, and the

Summary Prospectus dated February 1, 2025

This supplement provides new and additional information beyond that contained in the Prospectus and Summary Prospectus, and any previous supplements. It should be retained and read in conjunction with the Prospectus and Summary Prospectus, and any previous supplements.

Effective immediately, the information for Mark Steffen found under the heading Portfolio Manager(s) in the section titled Management (on page 14 of the Prospectus) as well as under the heading Subadvisers and Portfolio Managers in the section titled Management of the Funds on page 69 of the Prospectus, is hereby removed.

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE

ADVPRO-25-03

CM-25-01