American Century ETF Trust Statement of Additional Information (SAI) Supplement American Century® California Municipal Bond ETF American Century® Diversified Municipal Bond ETF American Century® Multisector Floating Income ETF American Century® Quality Diversified International ETF
Supplement dated August 1, 2026 n SAI dated May 21, 2026

The following replaces the entries for American Century California Municipal Bond ETF, American Century Diversified Municipal Bond ETF, American Century Multisector Floating Income ETF and American Century Quality Diversified International ETF in the first table in the Investment Advisor section on page 49 of the SAI:

Fund			Management Fee Rate Before Waiver
American Century California Municipal Bond ETF			0.25%
American Century Diversified Municipal Bond ETF			0.25%
American Century Multisector Floating Income ETF			0.19%
American Century Quality Diversified International ETF			0.33%

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