Prospectus by Investment Company (Form 497)

American Century ETF Trust Statement of Additional Information (SAI) Supplement Avantis® All Equity Markets ETF Avantis® All Equity Markets Value ETF Avantis® All International Markets Equity ETF Avantis® All International Markets Value ETF Avantis® Core Fixed Income ETF Avantis® Core Municipal Fixed Income ETF Avantis® Credit ETF Avantis® Emerging Markets Equity ETF Avantis® Emerging Markets ex-China Equity ETF Avantis® Emerging Markets Small Cap Equity ETF Avantis® Emerging Markets Value ETF Avantis® Inflation Focused Equity ETF Avantis® International Equity ETF Avantis® International Large Cap Value ETF Avantis® International Small Cap Equity ETF Avantis® International Small Cap Value ETF Avantis® Moderate Allocation ETF Avantis® Real Estate ETF Avantis® Responsible Emerging Markets Equity ETF Avantis® Responsible International Equity ETF Avantis® Responsible U.S. Equity ETF Avantis® Short-Term Fixed Income ETF Avantis® Total Equity Markets ETF Avantis® U.S. Equity ETF Avantis® U.S. Large Cap Equity ETF Avantis® U.S. Large Cap Value ETF Avantis® U.S. Mid Cap Equity ETF Avantis® U.S. Mid Cap Value ETF Avantis® U.S. Quality ETF Avantis® U.S. Small Cap Equity ETF Avantis® U.S. Small Cap Value ETF
Supplement dated March 21, 2026 n SAI dated January 1, 2026

The following replaces the first two paragraphs of the Costs Associated with Creation Transactions section on page 40 of the SAI:

A standard creation transaction fee is imposed to offset the transfer and other transaction costs associated with the issuance of Creation Units. The standard creation transaction fee is charged to the Authorized Participant on the day such Authorized

Participant creates a Creation Unit, and is the same, regardless of the number of Creation Units purchased by the Authorized Participant on the applicable Business Day. The Authorized Participant may also be required to cover certain brokerage, tax, foreign exchange, execution, market impact and other costs and expenses related to the execution of trades resulting from such transaction (up to the maximum amount shown below). If the costs of executing the transaction exceed the maximum additional charge, such charges will be paid by the fund. Authorized Participants will also bear the costs of transferring the Deposit Securities to a fund. Investors who use the services of a broker or other financial intermediary to acquire fund shares may be charged a fee for such services.

The following table sets forth each fund's standard creation transaction fees and maximum additional charge (as described above). Transaction fees may be waived in certain circumstances deemed appropriate by the trust. Circumstances in which a fund may waive transaction fees include, but are not limited to, portfolio rebalance transactions and transactions initiated for portfolio cash management purposes.

The following replaces the first two paragraphs of the Costs Associated with Redemption Transactions in the Redemption of Creation Units section on page 41 of the SAI:

A standard redemption transaction fee is imposed to offset transfer and other transaction costs that may be incurred by the funds. The standard redemption transaction fee is charged to the Authorized Participant on the day such Authorized Participant redeems a Creation Unit, and is the same regardless of the number of Creation Units redeemed by an Authorized Participant on the applicable Business Day. The Authorized Participant may also be required to cover certain brokerage, tax, foreign exchange, execution, market impact and other costs and expenses related to the execution of trades resulting from such transaction (up to the maximum amount shown below). If the costs of executing the transaction exceed the maximum additional charge, such charges will be paid by the fund. Authorized Participants will also bear the costs of transferring the Fund Securities from a fund to their account on their order. Investors who use the services of a broker or other financial intermediary to dispose of fund shares may be charged a fee for such services.

The following table sets forth each fund's standard redemption transaction fees and maximum additional charge (as described above). Transaction fees may be waived in certain circumstances deemed appropriate by the trust. Circumstances in which a fund may waive transaction fees include, but are not limited to, portfolio rebalance transactions and transactions initiated for portfolio cash management purposes.

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