Kaiser Aluminum director gets 786-share stock grant

arnold michael c reported acquisition or exercise transactions in this Form 4 filing.

Rhea-AI Filing Summary

arnold michael c reported acquisition or exercise transactions in this Form 4 filing.

Kaiser Aluminum Corporation director Michael C. Arnold received a grant of 786 shares of common stock as compensation. The award was made at no cash cost to him and increases his direct holdings to 11,445 shares. The grant consists of restricted stock, with all restrictions scheduled to lapse on June 4, 2027, effectively vesting the award on that date if conditions are met.

Insider Trade Summary

Grant/Award: 786 shares

Grant/Award 1 txn

Insider arnold michael c

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Common Stock, par value $0.01 per share	786	$0.00	$0.00

Holdings After Transaction: Common Stock, par value $0.01 per share — 11,445 shares (Direct)

Footnotes (1)

1. F1. Grant to the reporting person of restricted stock under the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan, as amended and restated. All restrictions will lapse on June 4, 2027.

Key Figures

Restricted stock grant: 786 shares Grant price: $0.0000 per share Total holdings after grant: 11,445 shares +1 more

4 metrics

Restricted stock grant 786 shares Common Stock granted June 4, 2026

Grant price $0.0000 per share Restricted stock award, non-cash compensation

Total holdings after grant 11,445 shares Director’s direct ownership following transaction

Restriction lapse date June 4, 2027 All restrictions on granted restricted stock

Key Terms

restricted stock, Equity and Incentive Compensation Plan, Form 4, Grant, award, or other acquisition

4 terms

restricted stock financial

"Grant to the reporting person of restricted stock under the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan"

Shares granted to an individual that carry limits on transfer or sale until certain conditions are met, such as staying with the company for a set time or hitting performance targets. Think of them as a locked gift that gradually opens; for investors they matter because they affect how many shares may enter the market later, signal management incentives and potential dilution, and reveal confidence in future company performance.

Equity and Incentive Compensation Plan financial

"under the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan, as amended and restated"

Form 4 regulatory

"INSIDER FILING DATA (Form 4)"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

Grant, award, or other acquisition financial

"transaction_code_description": "Grant, award, or other acquisition"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Kaiser Aluminum (KALU) director Michael C. Arnold report in this Form 4?

Director Michael C. Arnold reported receiving a grant of 786 shares of Kaiser Aluminum common stock. The shares are restricted stock awarded as compensation and were granted at no cash purchase price to him under the company’s 2021 Equity and Incentive Compensation Plan.

How many Kaiser Aluminum (KALU) shares were granted to the director and at what price?

The director was granted 786 shares of Kaiser Aluminum common stock at a reported price of $0.0000 per share. This indicates a stock-based compensation award rather than an open-market purchase, consistent with a restricted stock grant under the company’s equity plan.

When do the restrictions on the newly granted Kaiser Aluminum (KALU) shares lapse?

All restrictions on the 786 restricted shares will lapse on June 4, 2027. At that time, assuming applicable conditions are satisfied, the restricted stock will fully vest, and the director’s ownership of these shares will no longer be subject to vesting restrictions.

What is Michael C. Arnold’s total Kaiser Aluminum (KALU) shareholding after this grant?

Following the restricted stock grant, Michael C. Arnold directly holds 11,445 shares of Kaiser Aluminum common stock. This total reflects his position immediately after the 786-share award and represents his reported direct ownership in the company’s common stock.

Is this Kaiser Aluminum (KALU) Form 4 transaction an open-market buy or a compensation award?

The Form 4 transaction is a compensation-related award, not an open-market buy. It is coded as a grant or award acquisition and described as restricted stock granted under the 2021 Equity and Incentive Compensation Plan with no purchase price paid by the director.

Under which plan was the Kaiser Aluminum (KALU) restricted stock granted to the director?

The restricted stock was granted under the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan, as amended and restated. This plan is the company’s approved equity compensation program for issuing stock-based awards such as restricted stock to directors and other participants.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 06/05/2026 - 06:19 PM EDT Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

arnold michael c

(Last) (First) (Middle)

1550 WEST MCEWEN DRIVE

SUITE 500

(Street)

FRANKLIN TENNESSEE 37067

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
KAISER ALUMINUM CORP [ KALU ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/04/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock, par value $0.01 per share	06/04/2026		A		786(1)	A	$0(1)	11,445	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Grant to the reporting person of restricted stock under the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan, as amended and restated. All restrictions will lapse on June 4, 2027.

	/s/ Cherrie I. Tsai, with power of attorney for Michael C. Arnold	06/05/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)