March 23, 2026 - 144: Report of proposed sale of securities

144: Filer Information

Filer CIK

0001323719

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

(629) 252-7040

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

Blain Tiffany

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

Officer

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	7111	797415.9	16210443	03/23/2026	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	03/05/2026	RSU	Kaiser Aluminum	1848	03/23/2026	cash
common	03/05/2026	PSA	Kaiser Aluminum	4069	03/23/2026	cash
common	03/05/2026	RSU	Kaiser Aluminum	1194	03/23/2026	cash

* 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

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Kaiser Aluminum 1550 West McEwen Drive Suite 500 Franklin TN 37067	common	02/23/2026	15231	1875645

144: Remarks and Signature

Remarks

Date of Notice

03/23/2026

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/Mijo Suric, for UBS Financial Services Inc, as attorney-in-fact for Blain Tiffany

Form: 144

FORM 144