Prospectus by Investment Company (Form 497)

Filed pursuant to Rule 497(e)

under the Securities Act of 1933, as amended

Registration File No: 333-237048

Brandes International Equity Fund

(the "Fund")

A SERIES OF DATUM ONE SERIES TRUST

Supplement dated May 21, 2026
To the Prospectus dated July 29, 2025

IMPORTANT NOTICE REGARDING CHANGE IN INVESTMENT POLICY

In connection with a new regulatory requirement, the Board of Trustees of Datum One Series Trust has approved certain changes to the Fund's 80% investment policy, with such changes to be effective on July 29, 2026 (the "Effective Date"). These changes do not reflect a change in the investment objective or investment focus of the Fund, or the principal risks of investing in the Fund. On the Effective Date, the Fund's investment strategies will be revised to reflect changes to the Fund's 80% policy pursuant to Rule 35d-1 under the Investment Company Act of 1940. The revised 80% policy will state that, under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities. The following changes are being made to the Prospectus to reflect this change:

On page 2 of the Prospectus, the first paragraph under the heading "Principal Investment Strategies," is deleted in its entirety and replaced with the following:

The International Equity Fund invests primarily in equity securities of foreign companies. The Fund typically invests in foreign companies with market capitalizations (market value of publicly traded equity securities) greater than $5 billion at the time of purchase. A foreign company is determined to be "foreign" on the basis of its domicile, its principal place of business, its primary stock exchange listing, and/or the source of its revenues. Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities. Equity securities include common and preferred stocks, warrants and rights. The Fund may invest up to 30% of its total assets, measured at the time of purchase, in securities of companies located in emerging markets (including frontier markets). The Adviser considers an emerging market country to be any country which is in the MSCI EM Index or MSCI Frontier Markets Index or that, in the opinion of the Adviser, is generally considered to be an emerging market country by the international financial community. The Fund may invest up to 5% of its total assets, measured at the time of purchase, in any one company. From time to time, the Fund may invest more than 20% of its assets in any market sector, such as the financial sector or health care sector.

Additionally, on page 31 of the Prospectus, the first paragraph under the heading "INVESTMENT OBJECTIVE, POLICIES AND RISKS - Investment Policies - International Equity Fund," is deleted in its entirety and replaced with the following:

The International Equity Fund invests primarily in equity securities of foreign companies. The Fund typically invests in foreign companies with market capitalizations (market value of publicly traded equity securities) greater than $5 billion at the time of purchase. A foreign company is determined to be "foreign" on the basis of its domicile, its principal place of business, its primary stock exchange listing, and/or the source of its revenues. Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities. Equity securities include common and preferred stocks, warrants and rights. The Fund may invest up to 30% of its total assets, measured at the time of purchase, in securities of companies located in emerging market countries (including frontier market countries). The Adviser considers an emerging market country to be any country which is in the MSCI EM Index or MSCI Frontier Markets Index or that, in the opinion of the Adviser, is generally considered to be an emerging market country by the international financial community. The Fund may invest up to 5% of its total assets, measured at the time of purchase, in any one company. From time to time, the Fund may invest more than 20% of its assets in any market sector, such as the financial sector or health care sector.

This Supplement and the Prospectus should be retained for future reference.

1