Prospectus by Investment Company (Form 497)

OPTIMUM FUND TRUST

Optimum Large Cap Growth Fund

Optimum Large Cap Value Fund

Optimum Small-Mid Cap Growth Fund

Optimum Small-Mid Cap Value Fund

Optimum International Fund

Optimum Fixed Income Fund

(the "Funds")

Supplement to the Funds' Statement of Additional Information

dated July 31, 2025, as amended

The following information replaces the section in the Funds' SAI entitled "Management of the Trust - Trustees and officers":

Trustees and officers

The business and affairs of the Trust are managed under the direction of its Board. Certain officers and Trustees of the Trust hold identical positions in each of the funds in the Nomura Funds. The Trust's Trustees and principal officers are noted below along with their birthdates and their business experience for the past five years. The Trustees serve for indefinite terms until their resignation, death, or removal.

As of March 31, 2026, the officers and Trustees of the Trust directly owned less than 1% of the outstanding shares of each Class of the Fund.

The following information replaces the section in the Funds' SAI entitled "Management of the Trust - Board Leadership Structure - Size and composition of Board":

Size and composition of Board: The Board is currently composed of 9 Trustees. The Trustees believe that the current size of the Board is conducive to Board interaction, dialogue and debate, resulting in an effective decision-making body. The Board is composed of Trustees with a variety of professional backgrounds. The Board believes that the skill sets of its members are complementary and add to the overall effectiveness of the Board. In order to ensure that Board membership will be refreshed from time to time, the Board has adopted a mandatory retirement age of 75 for Trustees. As a result, a Trustee may serve until December 31 of the calendar year in which such Trustee reaches the age of 75. At the discretion of the other Trustees, active service for a particular Trustee may be extended for a limited period of time beyond a Trustee's normal retirement date. The Trustees also regard diversity as an important consideration in the present composition of the Board and the selection of qualified candidates to fill vacancies on the Board. Please see the following chart regarding the current diversity of the Board of Trustees:

The following information replaces the section in the Funds' SAI entitled "Management of the Trust - Board Leadership Structure - Nominating and Governance Committee":

Nominating and Governance Committee: The Committee conducts a variety of activities, including but not limited to: reviewing the Fund's Chief Compliance Officer compensation; overseeing the Board's annual self-assessment; reviewing and recommending any changes to Trustee compensation; and reviewing the performance of the Independent Trustees' counsel. The Nominating and Governance Committee also recommends Board members for vacancies and considers the qualifications of Board members. In reaching its determination that an individual should serve or continue to serve as a Trustee of the Trust, the committee considers, in light of the Trust's business and structure, the individual's

experience, qualifications, attributes and skills (the "Selection Factors"). No one Selection Factor is determinative, but some of the relevant factors that have been considered include: (i) the Trustee's business and professional experience and accomplishments, including prior experience in the financial services industry or on other boards; (ii) the ability to work effectively and collegially with other people; and (iii) how the Trustee's background and attributes contribute to the overall mix of skills and experience on the Board as a whole. Information on the business activities of the Trustees during the past five years appears in this SAI, and it is believed that the specific background of each Trustee demonstrates that each Trustee has appropriate Selection Factors to evidence the Trustee's ability to serve on the Board. In particular, Messrs. Chavers, Hancock, and Young, and Mses. Hutchinson, Belski, Gonzales-Burdin and Moret have each held senior management positions at major financial services firms, and each of these individuals has had experience dealing with mutual funds and / or asset managers prior to becoming Trustees. Mr. Mullin is an economist who teaches at Drexel University, and he is currently a principal in an economic consulting firm. He also was previously the Finance Director for the City of Philadelphia. Ms. Stalnecker was employed by E.I. du Pont de Nemours & Co., serving in numerous senior roles during her tenure, including Vice President and Treasurer, and most recently as Vice President of Corporate Productivity and Hospitality. She also serves on the Board of Directors of Leidos and Bioventus. The Nominating and Governance Committee consists of the following three Independent Trustees: Kevin G. Chavers, Chair, Pamela J. Moret, and Stephen P. Mullin. The Nominating and Governance Committee held four meetings during the Trust's last fiscal year.

Because everyone's tax situation is unique, you should consult your tax professional about federal, state, local or foreign tax consequences before making an investment in a Fund or acting on a distribution check (if applicable).

Please keep this Supplement for future reference.

This Supplement is dated April 23, 2026.