American Century ETF Trust Statement of Additional Information (SAI) Supplement Avantis® All Equity Markets ETF Avantis® All Equity Markets Value ETF Avantis® All International Core Equity 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. Core Equity 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 September 28, 2026 n SAI dated May 5, 2026

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The following replaces the Other Investment Companies section on page 25 of the SAI:

Other Investment Companies

Each of the funds may invest in other investment companies, such as closed-end investment companies, unit investment trusts, other exchange-traded funds (ETFs) and other open-end investment companies, provided that the investment is consistent with the fund’s investment policies and restrictions. Under the Investment Company Act, a fund’s investment in such securities, subject to certain exceptions, currently is limited to:

•3% of the total voting stock of any one investment company;

•5% of the fund’s total assets with respect to any one investment company; and

•10% of a fund’s total assets in the aggregate.

Such exceptions may include reliance on Rule 12d1-4 and Section 12(d)(1)(F) of the Investment Company Act. These provisions, subject to certain requirements, would permit a fund to invest in affiliated investment companies (other American Century mutual funds and ETFs) and unaffiliated investment companies in excess of the limitations described above.

A fund’s investments in other investment companies may include money market funds managed by the advisor. Investments in money market funds are not subject to the percentage limitations set forth above.

As a shareholder of another investment company, a fund would bear, along with other shareholders, its pro rata portion of the other investment company’s expenses, including advisory fees. These expenses would be in addition to the management fee that each fund bears directly in connection with its own operations.

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