Kaiser Aluminum Corporation

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On June 4, 2026, Kaiser Aluminum Corporation (the “Company”) held its Annual Meeting of Stockholders (the “2026 Annual Meeting”). At the 2026 Annual Meeting, the stockholders of the Company, upon recommendation of the Company’s Board of Directors (the “Board”), approved the amendment and restatement of the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan, as amended (the “2021 Plan”), to increase the number of shares of common stock, par value $0.01 per share, of the Company (“Common Stock”), available for awards under the 2021 Plan by 395,000 shares. We refer to the 2021 Plan, as newly amended and restated at the 2026 Annual Meeting, as the “Amended 2021 Plan.” Other than the increase in shares described above, the Amended 2021 Plan does not make any other material changes to the 2021 Plan. Subject to adjustment as described in the Amended 2021 Plan and the Amended 2021 Plan’s share counting rules, a total of 1,183,000 shares of Common Stock (consisting of 395,000 new shares approved by the Company’s stockholders at the 2026 Annual Meeting, 263,000 shares approved by the Company’s stockholders in 2024, and 525,000 shares approved by the Company’s stockholders in 2021) are available for awards granted under the Amended 2021 Plan. This description of the Amended 2021 Plan is qualified in its entirety by reference to the full text of the Amended 2021 Plan, which is incorporated by reference as Exhibit 10.1 to this Current Report on Form 8-K.

Item 5.07 Submission of Matters to a Vote of Security Holders. Below are the matters that were voted upon at the 2026 Annual Meeting and the final voting results as reported by our inspector of elections. 1. Election of Directors - The stockholders elected three Class I directors, each for a term expiring at the Company's 2029 Annual Meeting of Stockholders. Each received the affirmative vote of a majority of the votes cast at the 2026 Annual Meeting. The voting results were as follows: Nominee Name Votes For Votes Withheld Broker Non-Votes ───────────────────────────────────────────────────────────────────────────────────── James D. Hoffman 13,600,788.963056 796.383000 722.574.000000 Glenda J. Minor 14,118,306.174456 278,865.788600 722.574.000000 Brett E. Wilcox 13,838,262.963056 558,909.000000 722.574.000000 The other directors with terms continuing after the 2026 Annual Meeting are Michael C. Arnold, David A. Foster, Kimberly T. Glas, Richard P. Grimley, Keith A. Harvey and Donald J. Stebbins. 2. Advisory Vote on Executive Compensation - The Company's stockholders approved, on an advisory, non-binding basis, the compensation of the Company's named executive officers. The voting results were as follows: For Against Abstain Broker Non-Votes ────────────────────────────────────────────────────────────────────────────────── 14,207,656.775510 171,450.243473 18,088.486942 722.574.000000 The number of shares voting “for” constituted 98.68% of the total number of shares represented and entitled to vote at the meeting and actually voted on the proposal. 3. Ratification of the Selection of Independent Registered Public Accounting Firm - The Company's stockholders ratified the selection of Deloitte & Touche LLP as the independent registered public accounting firm for the Company for 2026. The voting results were as follows: For Against Abstain ──────────────────────────────────────────────────────────── 14,847,826.494528 251,817.441411 20,125.569986 The number of shares voting “for” constituted 98.20% of the total number of shares represented and entitled to vote at the meeting and actually voted on the proposal. 4. Approval of the Amended 2021 Plan - The Company's stockholders approved the Amended 2021 Plan. The voting results were as follows: For Against Abstain Broker Non-Votes ────────────────────────────────────────────────────────────────────────────────── 13,595,325.653799 785,562.439006 16,307.413120 722.574.000000 The number of shares voting “for” constituted 94.43% of the total number of shares represented and entitled to vote at the meeting and actually voted on the proposal.