January 23, 2020 State Street Bank and Trust Company Josiah Quincy Building

January 23, 2020

State Street Bank and Trust Company

Xxxxxx Xxxxxx Building

000 Xxxxxxx Xxxxxx

North Quincy, Massachusetts 02171

Location Code: JQB5

Attention: Xxxxxxx X. Xxxxxxx

Re: Master Custodian Agreement - New Portfolios

Ladies and Gentlemen:

Please be advised that the undersigned Fund has established two (2) new series of shares to be known as:

American Century ETF Trust - American Century Focused Dynamic Growth ETF

American Century ETF Trust - American Century Focused Large Cap Value ETF (the "New Portfolios').

In accordance with Section 18.6, the Additional Portfolios provision, of the Master Custodian Agreement dated as of July 29, 2011, (the "Custodian Agreement'') by and among each Fund party thereto and State Street Bank and Trust Company, the undersigned Fund hereby requests that your bank act as Custodian for the New ETF Portfolios under the terms of the Custodian Agreement. In connection with such request, the undersigned Fund hereby confirms to you, as of the date hereof, its representations and warranties set forth in Section 18.7 of the Custodian Agreement. Capitalized terms used herein without definition shall have the meanings ascribed to them in the Custodian Agreement.

Kindly indicate your acceptance of the foregoing by executing this letter agreement and returning a copy to the Fund.

Sincerely,

American Century Investment Management, Inc. on behalf of

American Century ETF Trust - American Century Focused Dynamic Growth ETF

American Century ETF Trust - American Century Focused Large Cap Value ETF

By: /s/ Xxxx X. Xxxxx

Name: Xxxx X. Xxxxx

Title: Vice President, Duly Authorized

Agreed and Accepted:

STATE STREET BANK AND TRUST COMPANY

By: /s/ Xxxxxx Xxxxxxxx

Name: Xxxxxx Xxxxxxxx

Title: Executive Vice President

Effective Date: January 24, 2020