0001710607 ck0001710607:AmericanCenturyETFTrustMember ck0001710607:S000063026Member 2026-01-01 2026-01-01 0001710607 2026-01-01 2026-01-01 0001710607 ck0001710607:AmericanCenturyETFTrustMember ck0001710607:S000063026Member ck0001710607:C000204482Member 2026-01-01 2026-01-01 pure iso4217:USD 497 2026-07-31 0001710607 false N-1A <div style="margin-bottom:3pt;margin-top:8pt;text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:99.861%"><tr><td style="width:1.0%"></td><td style="width:68.162%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:14.477%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:14.061%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:1.5pt 1pt;text-align:left;vertical-align:bottom"><div style="margin-top:5pt"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">American Century ETF Trust</span></div><div style="margin-bottom:10pt;margin-top:10pt"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:14pt;font-weight:700;line-height:120%">Prospectus Supplement</span></div><div style="margin-top:10pt"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:14pt;font-weight:700;line-height:100%">American Century</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:9.1pt;font-weight:700;line-height:100%;position:relative;top:-4.89pt;vertical-align:baseline">®</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:14pt;font-weight:700;line-height:100%"> Diversified Municipal Bond ETF</span></div></td><td colspan="6" style="padding:0 1pt;vertical-align:top"><div style="text-align:right"><img alt="ACI_Horiz_RGB_Black (Cropped).jpg" id="i-1" src="ck0001710607-20260731_g1.jpg" style="height:77px;margin-bottom:5pt;vertical-align:text-bottom;width:192px"/></div></td></tr><tr><td colspan="9" style="padding:1.5pt 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Supplement dated August 1, 2026 </span><span style="color:#000000;font-family:'Wingdings',sans-serif;font-size:10pt;font-weight:400;line-height:100%">n</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%"> Prospectus dated January 1, 2026</span></div></td></tr></table></div><div style="margin-bottom:3pt;margin-top:10pt"><span><br/></span></div><div style="margin-bottom:3pt;margin-top:3pt"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">The following replaces the </span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Annual Fund Operating Expenses</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%"> table in the </span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Fees and Expenses</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%"> section on page 2 of the prospectus:</span></div><div style="margin-top:5pt;text-align:center"><span><br/></span></div><div style="margin-top:5pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:82.762%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:15.038%"></td><td style="width:0.1%"></td></tr><tr><td colspan="6" style="padding:1.5pt 1pt;text-align:left;vertical-align:bottom"><div style="margin-bottom:2pt;margin-top:2pt"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">Annual Fund Operating Expenses</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%"> (expenses that you pay each year as a percentage of the value of your investment)</span></div></td></tr><tr><td colspan="3" style="border-top:1pt solid #000000;padding:1.5pt 1pt;text-align:left;vertical-align:middle"><div><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Management Fee</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline">1</span></div></td><td colspan="3" style="border-top:1pt solid #000000;padding:1.5pt 1pt;text-align:left;vertical-align:middle"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">0.25%</span></td></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:1.5pt 1pt;text-align:left;vertical-align:bottom"><div style="margin-bottom:2pt;margin-top:2pt"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Other Expenses</span></div></td><td colspan="3" style="border-top:1pt solid #000;padding:1.5pt 1pt;text-align:left;vertical-align:middle"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">0.00%</span></td></tr><tr><td colspan="3" style="border-bottom:1pt solid #000;border-top:1pt solid #000;padding:1.5pt 1pt;text-align:left;vertical-align:middle"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Total Annual Fund Operating Expenses</span></td><td colspan="3" style="border-bottom:1pt solid #000;border-top:1pt solid #000;padding:1.5pt 1pt;text-align:left;vertical-align:middle"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">0.25%</span></td></tr></table></div><div style="margin-top:1pt;padding-left:9pt;text-indent:-9pt"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:5.85pt;font-style:italic;font-weight:400;line-height:120%;position:relative;top:-3.15pt;vertical-align:baseline">1</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-style:italic;font-weight:400;line-height:120%">    The management fee has been restated to reflect the decrease in the management fee schedule effective August 1, 2026.</span></div><div><span><br/></span></div><div><span><br/></span></div><div><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">The following replaces the </span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Example</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%"> table in the </span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Fees and Expenses</span><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%"> section on page 2 of the prospectus:</span></div><div style="margin-bottom:3pt;margin-top:3pt"><span><br/></span></div><div style="margin-top:5pt;text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:23.900%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:23.900%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:23.900%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:23.900%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:1.5pt 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">1 year</span></td><td colspan="3" style="padding:1.5pt 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">3 years</span></td><td colspan="3" style="padding:1.5pt 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">5 years</span></td><td colspan="3" style="padding:1.5pt 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:100%">10 years</span></td></tr><tr><td colspan="3" style="border-bottom:1pt solid #000000;border-top:1pt solid #000000;padding:1.5pt 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">$26</span></td><td colspan="3" style="border-bottom:1pt solid #000000;border-top:1pt solid #000000;padding:1.5pt 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">$81</span></td><td colspan="3" style="border-bottom:1pt solid #000000;border-top:1pt solid #000000;padding:1.5pt 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">$141</span></td><td colspan="3" style="border-bottom:1pt solid #000000;border-top:1pt solid #000000;padding:1.5pt 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">$319</span></td></tr></table></div> American Century ETF Trust American Century® Diversified Municipal Bond ETF 2026-01-01 Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment) 0.0025 0.0000 0.0025 The management fee has been restated to reflect the decrease in the management fee schedule effective August 1, 2026. 26 81 141 319 The management fee has been restated to reflect the decrease in the management fee schedule effective August 1, 2026.