April 27, 2026 - 144: Report of proposed sale of securities

144: Filer Information

Filer CIK

0001289226

Filer CCC

XXXXXXXX

Is this a LIVE or TEST Filing?

LIVE

TEST

Submission Contact Information

Name

Phone

E-Mail Address

144: Issuer Information

Name of Issuer

Kaiser Aluminum

SEC File Number

001-09447

Address of Issuer

1550 West McEwen Drive
Suite 500
Franklin
TENNESSEE
37067

Phone

6292527040

Name of Person for Whose Account the Securities are To Be Sold

Brett Wilcox

See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.

Relationship to Issuer

Board Member

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	UBS Financial Services Inc 1000 Harbor Blvd 3rd Floor Weehawken NJ 07086	15000	2625000	16340606	04/27/2026	Nasdaq

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	06/04/2013	RSU	Kaiser Aluminum	1478	06/04/2013	N/A
common	06/04/2014	RSU	Kaiser Aluminum	1384	06/04/2014	N/A
Common	06/02/2015	RSU	Kaiser Aluminum	1158	06/02/2015	N/A
Common	05/26/2017	RSU	Kaiser Aluminum	1078	05/26/2017	N/A
Common	06/04/2016	RSU	Kaiser Aluminum	373	06/04/2016	N/A
Common	06/06/2019	RSU	Kaiser Aluminum	336	06/06/2019	N/A
Common	06/14/2019	RSU	Kaiser Aluminum	1001	06/14/2019	N/A
Common	06/06/2020	RSU	Kaiser Aluminum	1185	06/06/2020	N/A
Common	06/10/2020	RSU	Kaiser Aluminum	491	06/10/2020	N/A
Common	06/03/2021	RSU	Kaiser Aluminum	266	06/03/2021	N/A
Common	06/10/2021	RSU	Kaiser Aluminum	1756	06/10/2021	N/A
Common	06/02/2022	RSU	Kaiser Aluminum	611	06/02/2022	N/A
Common	06/03/2022	RSU	Kaiser Aluminum	952	06/03/2022	N/A
Common	06/02/2023	RSU	Kaiser Aluminum	229	06/02/2023	N/A
Common	06/07/2024	RSU	Kaiser Aluminum	2060	06/07/2024	N/A
Common	06/11/2024	RSU	Kaiser Aluminum	642	06/11/2024	N/A

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Nothing to Report

144: Remarks and Signature

Remarks

Brett Wilcox is on the board of Kaiser Aluminum, The Brett E. Wilcox Trust dtd 07/02/2019 is the seller.

Date of Notice

04/27/2026

ATTENTION:

The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.

Signature

/s/JOSEPH CASSIDY, for UBS Financial Services Inc, as attorney-in-fact for Brett Wilcox

Form: 144

FORM 144