KAISER ALUMINUM CORP

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

PROXY STATEMENT PURSUANT TO SECTION 14(a) OF

THE SECURITIES EXCHANGE ACT OF 1934 (AMENDMENT NO. )

Filed by the Registrant ☑

Filed by a Party other than the Registrant ☐

Check the appropriate box:

☐ Preliminary Proxy Statement

☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☑ Definitive Proxy Statement

☐ Definitive Additional Materials

☐ Soliciting Material Pursuant to §240.14a-12

(Name of Registrant as Specified in Its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

☑ No fee required

☐ Fee paid previously with preliminary materials

☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

LETTER TO OUR STOCKHOLDERS

FROM OUR CHAIRMAN OF THE BOARD, PRESIDENT AND CHIEF EXECUTIVE OFFICER

AND OUR LEAD INDEPENDENT DIRECTOR

April 28, 2026

Dear Stockholder:

On behalf of our Board of Directors and management team, we thank you for your continued support of Kaiser Aluminum Corporation. It is our pleasure to invite you to attend the Annual Meeting of Stockholders to be held at the Company's corporate office at 1550 West McEwen Drive, Suite 500, Franklin, Tennessee 37067, on Thursday, June 4, 2026, at 9:00 a.m. Central Time. While we do not expect to make a separate presentation, we expect our directors and officers to be present at the Annual Meeting and available to respond to any questions you may have.

Your vote is very important to us. Whether or not you plan to attend the Annual Meeting, we urge you to vote your shares as promptly as possible. Details of the business to be conducted at the Annual Meeting are included in this Proxy Statement, which we encourage you to read carefully. You may submit your voting instructions over the Internet or by telephone as indicated on the enclosed proxy card or by completing, signing and dating the enclosed proxy card and returning it by mail in the accompanying envelope. If you plan to attend the Annual Meeting, please review the information on attendance provided in this Proxy Statement.

We would like to share with you several areas of particular significance in advance of our Annual Meeting and in connection with our distribution of this Proxy Statement:

2025 PERFORMANCE HIGHLIGHTS

2025 was a defining year for Kaiser as we advanced our strategy and delivered strong performance. We are proud of our team’s dedication and the progress achieved in a complex market environment as we executed on objectives we believe will position Kaiser to continue to achieve long‑term value creation. Importantly, we strengthened our balance sheet and completed the most significant capital investment cycle in our recent history. Our unwavering focus on serving the evolving needs of our customers remained central to our success and will continue to guide us in the years ahead.

We delivered 2025 net sales and conversion revenue of $3.37 billion and $1.45 billion, respectively. Additionally, we were pleased to report enhanced profitability with 2025 net income of $113 million, or $6.77 per diluted share, along with record adjusted earnings before interest, taxes, depreciation, and amortization (adjusted EBITDA) of $310 million. This resulted in margin improvement to 3.4% from 2.2% in 2024 and in a significant improvement in our adjusted EBITDA margin (which is calculated as adjusted EBITDA as a percentage of conversion revenue) to 21.3% from 16.6% in 2024. Please refer to “Appendix A” of this Proxy Statement for reconciliations of measures from generally accepted accounting principles (“GAAP”) measures to non-GAAP measures such as conversion revenue, adjusted EBITDA and adjusted EBITDA margin.

We ended 2025 with ample liquidity, underscoring the strength of our balance sheet and the progress made in improving our capital structure. During the year, we extended the term of our $575 million revolving credit facility to 2030, completed a $500 million offering of senior notes due 2034, and redeemed all $500 million aggregate principal amount of our notes due 2028. In addition, our enhanced profitability enabled us to reduce our net leverage to 3.4x at December 31, 2025 from 4.3x at December 31, 2024, further strengthening our long-term financial flexibility. Our capital allocation priorities remain focused on investing in high return organic growth opportunities, maintaining a strong balance sheet, and returning capital to our stockholders.

As a specialty metals company, we supply highly-engineered aluminum solutions designed to meet the critical performance requirements of the demanding end markets we serve, including aerospace and high strength, packaging, general engineering, automotive extrusions, and other industrial applications. In aerospace and high strength, we navigated a transitional year as destocking eased and demand in business jet, defense, and space applications remained solid, positioning the business to support rising commercial aircraft build rates in 2026. Packaging advanced its mix shift toward coated products, supported by strong underlying demand trends. General engineering benefited from low customer inventories and steady demand for our Kaiser Select® products, while automotive remained resilient amid market uncertainty.

Our position as a preferred supplier is anchored in superior product quality, on-time delivery, and service excellence, supported by a deep understanding of the evolving needs of our customers. The completion of our multi-year investment cycle positions us to participate meaningfully in a rebound across key markets and continue guiding the business decisions that shape our path forward. In 2025, we completed both the commissioning of our fourth coating line at our Warrick rolling mill, which enables the conversion of approximately 25% of our existing mix to higher margin coated products for packaging customers, and the execution of the Phase VII expansion at our Trentwood rolling mill to increase capacity for high value flat rolled products serving aerospace and general engineering applications.

CORPORATE VALUES & SUSTAINABILITY

Our corporate values of being a preferred investment, a preferred supplier, a preferred employer, a preferred customer, and a valued corporate citizen continue to guide how we pursue sustainable business value creation and form the foundation of our culture and strategy. In 2025, we:

•

Enhanced our position as a preferred investment by delivering long-term value to our stockholders through disciplined capital allocation, strong governance, and consistent stockholder returns. In 2025, we invested $137 million in capital expenditures and returned $51 million to our stockholders through quarterly dividends, marking our 19th consecutive year of dividend payments. Major project execution is now largely behind us, allowing us to intensify our focus on reducing manufacturing and operating costs to maximize returns. We remain committed to our ongoing board refreshment, stakeholder engagement, and compensation practices that support long-term growth and stockholder feedback.

•

Advanced our role as a preferred supplier by delivering best-in-class customer service, expanding our Kaiser Select® product portfolio, and progressing toward our 2030 GHG emissions intensity reduction targets. Circularity remains central to both Kaiser and the aluminum industry, and we continue to work with our customers, suppliers, and industry partners to increase the use of recycled aluminum.

•

Strengthened our standing as a preferred employer through our continued focus on safety, including strong total case incident rate, lost-time case incident rate, and days away, restricted or transferred rates, leadership development and workforce engagement. We also expanded recruitment and retention efforts, advanced leadership and development programs, and sustained a clear focus on career advancement and succession planning that builds a strong leadership pipeline for Kaiser.

•

Maintained our commitment as a preferred customer by partnering closely with our suppliers to secure quality, reliable, and responsible sourcing consistent with our Supplier Code of Conduct and Conflict Minerals Sourcing Policy.

•

Continued to serve as a valued corporate citizen by prioritizing social responsibility across our operating communities, engaging local stakeholders to understand and help address community needs, including through formal mechanisms such as the Warrick facility Community Advisory Board, and providing financial and in-kind support in areas of impact.

SUMMARY

We are proud of the results our team delivered in 2025, which strengthened our competitive position and set Kaiser up for continued growth in 2026. Our focused portfolio of high performance and application-specific solutions in select and diversified markets, along with stronger market visibility and the capabilities we have built across the business, reinforce our ability to deliver sustainable long-term value for stockholders. Across our portfolio, we are sharpening our focus on cost reduction, operating leverage, and customer service excellence to increase returns. As we celebrate Kaiser’s 80 th anniversary, we enter 2026 with strong momentum, solid visibility across our end markets, and the benefit of having largely completed major growth investments. This positions us to focus on harvesting returns, expanding margins, and generating meaningful free cash flow. Our five corporate values will continue to guide how we lead, invest, and deliver value as we move into this next chapter.

Thank you to our stockholders, employees and their families, customers, suppliers, and all stakeholders for their continued commitment and support of Kaiser.

1550 West McEwen Drive, Suite 500

Franklin, Tennessee 37067

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON June 4, 2026

NOTICE IS HEREBY GIVEN that the 2026 Annual Meeting of Stockholders (the "Annual Meeting") of Kaiser Aluminum Corporation (the "Company") will be held at the Company's corporate office, located at 1550 McEwen Drive, Suite 500, Franklin, Tennessee 37067, on Thursday, June 4, 2026, at 9:00 a.m., Central Time, for the following purposes:

(1)

To elect three members to our board of directors for three-year terms to expire at our 2029 annual meeting of stockholders;

(2)

To approve, on a non-binding, advisory basis, the compensation of our named executive officers as disclosed in the accompanying Proxy Statement;

(3)

To ratify the selection of Deloitte & Touche LLP as our independent registered public accounting firm for 2026;

(4)

To approve the amendment and restatement of the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan; and

(5)

To consider such other business as may properly come before the Annual Meeting or any adjournments thereof.

Information concerning the matters to be acted upon at the Annual Meeting is set forth in the accompanying Proxy Statement. This notice and the accompanying proxy materials are being mailed or made available to stockholders on or about April 28, 2026.

The close of business on April 17, 2026 has been fixed as the record date for determining the stockholders entitled to notice of, and to vote at, the Annual Meeting or any adjournments thereof.

We urge stockholders to vote by proxy by submitting voting instructions over the Internet or by telephone as indicated on the enclosed proxy card or by completing, signing and dating the enclosed proxy card and returning it by mail in the accompanying envelope, which does not require postage if mailed in the United States.

By Order of the Board of Directors

John M. Donnan

Executive Vice President, Chief Administrative

Officer and General Counsel

April 28, 2026

Franklin, Tennessee

PROPOSALS AND BOARD RECOMMENDATIONS

Proposal 1 - Election of Directors

The board of directors recommends a vote "FOR ALL" of the persons nominated by the board of directors.

Additional information about our directors and their respective qualifications may be found beginning on page 5.

Proposal 2 - Advisory Vote to Approve Named Executive Officer Compensation

The board of directors recommends a vote "FOR" the approval, on a non-binding, advisory basis, of the compensation of our named executive officers as disclosed in this Proxy Statement.

Additional information about executive compensation may be found beginning on page 12.

Proposal 3 - Ratification of Appointment of Independent Registered Public Accounting Firm

The board of directors recommends a vote "FOR" the ratification of the audit committee's selection of Deloitte & Touche LLP as our independent registered public accounting firm for 2026.

Additional information about the independent registered public accounting firm may be found beginning on page 15.

Proposal 4 - Approval of the Amendment and Restatement of the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan

The board of directors recommends a vote "FOR" the approval of the amendment and restatement of the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan.

Additional information about the amendment and restatement of the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan may be found beginning on page 15.

PROXY STATEMENT SUMMARY

Our financial results for 2025 exceeded our outlook and reflected a year of consistent execution. This summary highlights information contained elsewhere in this Proxy Statement but does not contain all of the information that you should consider. We encourage you to read the entire Proxy Statement for more information about these topics prior to voting.

(1)

See Appendix A of this Proxy Statement for reconciliations of measures from GAAP to non-GAAP. While our use of terms such as EBITDA, “adjusted” or "Conversion Revenue" is not intended to be (and should not be relied on) in lieu of the comparable captions under GAAP to which these metrics are reconciled, those terms are intended to provide greater clarity of the impact of certain material items on the GAAP measure and are not intended to imply those terms should be excluded.

Our corporate values serve as the foundation for our culture and guiding principles driving our daily operations, strategic initiatives and long-term success.

i

ii

EXECUTIVE COMPENSATION HIGHLIGHTS

Our incentive programs are designed to “pay for performance,” and we expect payouts to be impacted by business/economic conditions. As described in further detail in the “Executive Compensation - Compensation Discussion and Analysis” section of this Proxy Statement, or CD&A, our 2025 compensation program was developed and designed to:

•

align the interest of our named executive officers and stockholders by tying a significant portion of compensation to enhancing total shareholder return ("TSR");

•

attract, motivate and retain highly experienced executives with significant industry experience vital to our short-term and long-term success, profitability and growth;

•

deliver a mix of fixed and at-risk compensation with the portion of compensation at risk increasing with seniority;

•

tie our executive compensation to our ability to pay and safety, quality and delivery and individual performance directly linked to our strategic initiatives; and

•

require strong financial performance as we continue to invest in our business

iii

In 2025, the compensation of our named executive officers consisted primarily of the following components:

•

a base salary (1) compensating each named executive officer based on the level and scope of responsibility, individual expertise and prior experience and (2) providing a fixed amount of cash compensation upon which our named executive officers can rely;

•

a short-term annual cash incentive (1) payable only if our company achieved certain Adjusted EBITDA, safety, quality, and delivery performance, (2) with positive and negative adjustments to individual awards, in exceptional instances, approved by our compensation committee, based on individual, facility, and/or functional area performance, as well as performance against other strategic initiatives, and (3) capped at 2.5 times target; and

•

an equity-based, long-term incentive designed to align compensation with the interests of our stockholders and to enhance retention of our named executive officers consisting of (1) restricted stock units with three-year cliff vesting and (2) performance shares, which vest, if at all, based on our performance against demanding underlying metrics over the applicable three-year performance period.

Because grants under our long-term incentive program are outstanding for three years, at any time we have three over-lapping long-term incentive programs outstanding. The underlying metrics applicable to the performance shares can vary as our compensation committee assesses the effectiveness of our outstanding programs, metrics critical to our long-term success, feedback from our stockholders and compensation trends. The following table describes the performance share metrics (described more fully below) for our 2023-2025, 2024-2026 and 2025-2027 long-term incentive programs:

Our compensation committee, working with its independent compensation consultant, Meridian Compensation Partners, LLC (referred to herein as Meridian), reviews, evaluates and updates our compensation peer group, which includes companies in both similar and different industries, at least annually. For 2025, our compensation committee approved a 22-company peer group more fully described in our CD&A section. Due to the differences in size among the companies in our peer group, Meridian uses a regression analysis to adjust survey data results based on our revenue as compared to the revenue of other companies in our peer group.

Pay for Performance

The table below summarizes the performance metrics under our 2025 short-term incentive plan ("2025 STI Plan") and 2025-2027 long-term incentive plan initiated in 2025 ("2025-2027 LTI Plan") for our named executive officers:

• Safety performance is measured using our total case incident rate ("TCIR") and lost-time case incident rate ("LCIR"). Quality performance is measured using our no-fault claim rate. Delivery performance is measured by our on-time delivery rate.

** As noted, the individual modifier is discretionary and, with respect to our executive officers, only used in exceptional instances approved by the compensation committee based on actual performance, including individual, facility and/or functional area performance, as well as performance against other strategic initiatives.

The following summarizes the key features and our performance against the metrics under our 2025 STI Plan and our 2023-2025 long-term incentive plan completed in 2025 ("2023-2025 LTI Plan"):

iv

2025 STI Plan

The final multiplier of our 2025 STI Plan, including the impact of all performance metrics, was 1.85x. The table below summarizes the performance metrics and payout potential under our 2025 STI Plan and our performance against each of the metrics:

*Total may not sum due to rounding.

2023-2025 LTI Plan

As discussed in more detail below, for the 2023 to 2025 performance period, the total performance share payout under the 2023-2025 LTI Plan was 183%.

Annual Performance Award Payouts under Long-Term Incentive Plans

The table below reflects our annual performance award payouts for the last three years under our completed long-term incentive plans.

v

Performance Share Award Payouts Based on Relative TSR

For our 2023-2025 LTI Plan, 60% of the performance shares granted to our named executive officers were subject to our TSR performance metric over the applicable three-year performance period compared to the TSR of the other companies comprising the S&P SmallCap 600 Materials and S&P MidCap 400 Materials Indices.

In considering constituents for the S&P SmallCap 600 Materials and S&P MidCap 400 Materials Indices, S&P Dow Jones Indices currently looks for companies (1) with market capitalization of between $1.2 billion and $8.0 billion and between $8.0 billion and $22.7 billion, respectively, (2) meeting certain float requirements, (3) with a U.S. domicile, (4) required to file Securities and Exchange Commission ("SEC") annual reports, and (5) listed on a major U.S. exchange, among other factors. The beginning and ending stock prices used to determine our TSR are calculated using the 20-trading day average preceding the beginning and end of the performance period. Based on our relative TSR performance for the 2023-2025 performance period, the multiplier for such metric was 172%, resulting in a weighted multiplier for such metric of 103%.

The chart below illustrates the relative TSR performance payout multipliers for our performance share awards under the 2021-2023, 2022-2024 and 2023-2025 long-term incentive programs:

Performance Share Award Payout Based on Adjusted EBITDA Margin

For our 2023-2025 LTI Plan, 40% of the performance shares granted to our named executive officers were subject to an Adjusted EBITDA margin performance metric, calculated by our Adjusted EBITDA as a percentage of conversion revenue over the three-year performance period. Our conversion revenue is calculated as our net sales less the hedged cost of alloyed metals. Based on our Adjusted EBITDA margin performance for the 2023-2025 performance period, the multiplier for such metric was 200%, resulting in a weighted multiplier for such metric of 80%.

2025 Total CEO Compensation

As previously noted, the mix of our CEO’s total target compensation is heavily weighted toward performance-based compensation with more than 80% of the total target compensation being at-risk (short- and long-term compensation), more than 60% of the total target compensation being long-term, and 50% of the long-term target being allocated to performance shares.

vi

The market pay analysis performed by Meridian at the end of 2025 reflected that the total target compensation of our CEO for 2025 was 15% below the median of our compensation peer group and that our CEO’s (1) base salary was approximately 8% below the median base salary, (2) short-term incentive target was approximately 16% below the median and (3) long-term incentive target was approximately 20% below the median.

vii

1550 West McEwen Drive, Suite 500

Franklin, Tennessee 37067

PROXY STATEMENT

FOR

ANNUAL MEETING OF STOCKHOLDERS

To Be Held on June 4, 2026

TABLE OF CONTENTS

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Stockholders to be held on June 4, 2026: The Proxy Statement and our Annual Report to Stockholders are available at www.envisionreports.com/kalu.