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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

☒ | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2025

☐ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from __________ to __________

Commission File Number: 1-09447

KAISER ALUMINUM CORPORATION

(Exact name of registrant as specified in its charter)

Delaware |  | 94-3030279
(State of incorporation) |  | (I.R.S. Employer Identification No.)

1550 West McEwen Drive, Suite 500 |  |
Franklin, Tennessee |  | 37067
(Address of principal executive offices) |  | (Zip Code)

(629) 252-7040

(Registrant’s telephone number, including area code)

(Former name, former address and former fiscal year, if changed since last report)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class | Trading symbol | Name of each exchange on which registered
Common stock, par value $0.01 per share | KALU | Nasdaq Global Select Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months, and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer | ☒ |  | Accelerated filer | ☐
Non-accelerated filer | ☐ |  | Smaller reporting company | ☐
|  |  | Emerging growth company | ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of October 20, 2025, there were 16,206,255 shares of common stock of the registrant outstanding.

COMMONLY USED OR DEFINED TERMS

Term | Definition
Adjusted EBITDA | Earnings before interest, taxes, depreciation and amortization adjusted for non-run-rate items
Aero/HS Products | 2000, 7000 and certain 6000 series alloys products used in the Aerospace, Defense, Space and other end markets requiring high strength applications
Alloy(s) | Certain metals such as copper, zinc, magnesium, manganese and silicon added to primary aluminum to obtain certain attributes
AOCI | Accumulated other comprehensive income (loss)
ASU | Accounting Standards Update
Automotive Extrusions | 6000 series extruded aluminum products used in automotive applications
COGS | Cost of products sold, excluding depreciation and amortization
FIFO | First-in, first-out inventory valuation methodology
Form 10-Q | This Quarterly Report on Form 10-Q
GAAP | United States Generally Accepted Accounting Principles
GE Products | 6000 series alloys products used in the General Engineering end markets
LIFO | Last-in, first-out inventory valuation methodology
LME | London Metal Exchange
Metal Price Lag | Management’s estimate of the financial impact resulting from the timing difference between aluminum prices included within Hedged Cost of Alloyed Metal and the weighted average market price for aluminum during the period, based on MWTP (defined below), multiplied by our shipment volume during the periods. Metal Price Lag will generally increase our earnings in times of rising primary aluminum prices and decrease our earnings in times of declining primary aluminum prices.
MWTP | Midwest Transaction Price is equal to the LME aluminum price plus a Midwest premium
Newark | Kaiser Aluminum manufacturing facility located in Heath, Ohio, a suburb of Newark, Ohio
OPEB | Other Post Employment Benefits
Packaging | 3000 and 5000 series alloys products used in the beverage and food packaging end markets
Revolving Credit Facility | Revolving credit facility with Wells Fargo Bank, National Association, as administrative agent, and the other financial institutions party thereto
Salaried VEBA | Salaried Voluntary Employees' Beneficiary Association
SEC | Securities and Exchange Commission
Senior Notes | Collectively, the fixed-rate unsecured notes we issued during the years ended December 31, 2019 and 2021 at the following interest rates and aggregate principal amounts, respectively: (i) 4.625% and $500.0 million; and (ii) 4.50% and $550.0 million
Term SOFR | Forward looking term rate based on the Secured Overnight Financing Rate
Trentwood | Kaiser Aluminum manufacturing facility located in Spokane Valley, Washington
WAC | Weighted average cost inventory valuation methodology
Warrick | Kaiser Aluminum manufacturing facility located in Newburgh, Indiana, in the county of Warrick

TABLE OF CONTENTS

PART I |  |
Item 1. Financial Statements |  | 1
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations |  | 28
Item 3. Quantitative and Qualitative Disclosures About Market Risk |  | 38
Item 4. Controls and Procedures |  | 39
PART II |  |
Item 1. Legal Proceedings |  | 40
Item 1A. Risk Factors |  | 40
Item 2. Unregistered Sales of Equity Securities and Use of Proceeds |  | 40
Item 3. Defaults Upon Senior Securities |  | 40
Item 4. Mine Safety Disclosures |  | 40
Item 5. Other Information |  | 40
Item 6. Exhibits |  | 41
SIGNATURES |  | 42

2

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

PART I – FINANCI AL INFORMATION

Item 1. Financi al Statements

CONSOLIDATED BALANCE SHEETS (UNAUDITED)

|  | As of September 30, 2025 |  |  | As of December 31, 2024 As Adjusted 1 |
|  | (In millions of dollars, except share and per share amounts) |
ASSETS |  |  |  |  |  |
Current assets: |  |  |  |  |  |
Cash and cash equivalents |  | $ | 17.2 |  |  | $ | 18.4 |
Receivables: |  |  |  |  |  |
Trade receivables, net |  |  | 388.9 |  |  |  | 319.7 |
Other |  |  | 32.3 |  |  |  | 22.2 |
Contract assets |  |  | 54.0 |  |  |  | 73.4 |
Inventories |  |  | 702.3 |  |  |  | 601.9 |
Prepaid expenses and other current assets |  |  | 49.5 |  |  |  | 39.0 |
Total current assets |  |  | 1,244.2 |  |  |  | 1,074.6 |
Property, plant and equipment, net |  |  | 1,199.8 |  |  |  | 1,161.2 |
Operating lease assets |  |  | 24.1 |  |  |  | 27.2 |
Deferred tax assets, net |  |  | 1.4 |  |  |  | 4.0 |
Intangible assets, net |  |  | 42.1 |  |  |  | 45.5 |
Goodwill |  |  | 18.8 |  |  |  | 18.8 |
Other assets |  |  | 61.7 |  |  |  | 78.6 |
Total assets |  | $ | 2,592.1 |  |  | $ | 2,409.9 |
LIABILITIES AND STOCKHOLDERS’ EQUITY |  |  |  |  |  |
Current liabilities: |  |  |  |  |  |
Accounts payable |  | $ | 392.8 |  |  | $ | 266.9 |
Accrued salaries, wages and related expenses |  |  | 58.4 |  |  |  | 54.3 |
Other accrued liabilities |  |  | 49.5 |  |  |  | 79.3 |
Total current liabilities |  |  | 500.7 |  |  |  | 400.5 |
Long-term portion of operating lease liabilities |  |  | 22.8 |  |  |  | 25.2 |
Pension and OPEB |  |  | 70.6 |  |  |  | 71.4 |
Deferred tax liabilities |  |  | 64.6 |  |  |  | 44.1 |
Long-term liabilities |  |  | 84.4 |  |  |  | 84.0 |
Long-term debt, net |  |  | 1,042.9 |  |  |  | 1,041.6 |
Total liabilities |  |  | 1,786.0 |  |  |  | 1,666.8 |
Commitments and contingencies – Note 7 |  |  |  |  |  |
Stockholders’ equity: |  |  |  |  |  |
Preferred stock, 5,000,000 shares authorized at both September 30, 2025 and December 31, 2024; no shares were issued and outstanding at September 30, 2025 and December 31, 2024 |  |  | — |  |  |  | — |
Common stock, par value $0.01, 90,000,000 shares authorized at both September 30, 2025 and December 31, 2024; 23,041,541 shares issued and 16,206,255 shares outstanding at September 30, 2025; 22,931,184 shares issued and 16,095,898 shares outstanding at December 31, 2024 |  |  | 0.2 |  |  |  | 0.2 |
Additional paid in capital |  |  | 1,128.0 |  |  |  | 1,117.0 |
Retained earnings |  |  | 127.1 |  |  |  | 81.3 |
Treasury stock, at cost, 6,835,286 shares at both September 30, 2025 and December 31, 2024 |  |  | (475.9 | ) |  |  | (475.9 | )
AOCI |  |  | 26.7 |  |  |  | 20.5 |
Total stockholders’ equity |  |  | 806.1 |  |  |  | 743.1 |
Total liabilities and stockholders' equity |  | $ | 2,592.1 |  |  | $ | 2,409.9 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.

The accompanying notes to interim consolidated financial statements are an integral part of these statements.

1

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

STATEMENTS OF CONSOLIDA TED INCOME (UNAUDITED)

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |  |  | 2025 |  |  | 2024 As Adjusted 1 |
|  | (In millions of dollars, except share and per share amounts) |
Net sales |  | $ | 843.5 |  |  | $ | 747.7 |  |  | $ | 2,444.0 |  |  | $ | 2,258.6 |
Costs and expenses: |  |  |  |  |  |  |  |  |  |  |  |
Cost of products sold, excluding depreciation and amortization |  |  | 728.8 |  |  |  | 676.0 |  |  |  | 2,125.0 |  |  |  | 1,997.1 |
Depreciation and amortization |  |  | 32.0 |  |  |  | 29.0 |  |  |  | 91.6 |  |  |  | 86.8 |
Selling, general, administrative, research and development |  |  | 33.9 |  |  |  | 28.8 |  |  |  | 97.3 |  |  |  | 93.0 |
Restructuring costs |  |  | — |  |  |  | 0.7 |  |  |  | 1.9 |  |  |  | 7.6 |
Other operating charges, net |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.4 |
Total costs and expenses |  |  | 794.7 |  |  |  | 734.5 |  |  |  | 2,315.8 |  |  |  | 2,184.9 |
Operating income |  |  | 48.8 |  |  |  | 13.2 |  |  |  | 128.2 |  |  |  | 73.7 |
Other (expense) income: |  |  |  |  |  |  |  |  |  |  |  |
Interest expense |  |  | (12.4 | ) |  |  | (10.7 | ) |  |  | (36.1 | ) |  |  | (33.3 | )
Other income, net – Note 9 |  |  | 11.4 |  |  |  | 8.7 |  |  |  | 14.4 |  |  |  | 19.1 |
Income before income taxes |  |  | 47.8 |  |  |  | 11.2 |  |  |  | 106.5 |  |  |  | 59.5 |
Income tax provision |  |  | (8.3 | ) |  |  | (2.4 | ) |  |  | (22.2 | ) |  |  | (13.6 | )
Net income |  | $ | 39.5 |  |  | $ | 8.8 |  |  | $ | 84.3 |  |  | $ | 45.9 |
Net income per common share: |  |  |  |  |  |  |  |  |  |  |  |
Basic |  | $ | 2.44 |  |  | $ | 0.54 |  |  | $ | 5.22 |  |  | $ | 2.85 |
Diluted |  | $ | 2.38 |  |  | $ | 0.54 |  |  | $ | 5.10 |  |  | $ | 2.81 |
Weighted-average number of common shares outstanding (in thousands): |  |  |  |  |  |  |  |  |  |  |  |
Basic |  |  | 16,192 |  |  |  | 16,087 |  |  |  | 16,156 |  |  |  | 16,062 |
Diluted |  |  | 16,612 |  |  |  | 16,335 |  |  |  | 16,511 |  |  |  | 16,291 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.

The accompanying notes to interim consolidated financial statements are an integral part of these statements.

2

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

STATEMENTS OF CONSOLIDATED COM PREHENSIVE INCOME (UNAUDITED)

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |  |  | 2025 |  |  | 2024 As Adjusted 1 |
|  | (In millions of dollars) |  |  | (In millions of dollars) |
Net income |  | $ | 39.5 |  |  | $ | 8.8 |  |  | $ | 84.3 |  |  | $ | 45.9 |
Other comprehensive income (loss), net of tax – Note 8: |  |  |  |  |  |  |  |  |  |  |  |
Defined benefit plans |  |  | 0.2 |  |  |  | 0.5 |  |  |  | 0.7 |  |  |  | (0.1 | )
Cash flow hedges |  |  | (0.7 | ) |  |  | 1.6 |  |  |  | 5.5 |  |  |  | 3.3 |
Other comprehensive (loss) income, net of tax |  |  | (0.5 | ) |  |  | 2.1 |  |  |  | 6.2 |  |  |  | 3.2 |
Comprehensive income |  | $ | 39.0 |  |  | $ | 10.9 |  |  | $ | 90.5 |  |  | $ | 49.1 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.

The accompanying notes to interim consolidated financial statements are an integral part of these statements.

3

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

STATEMENTS OF CONSOLIDATED STO CKHOLDERS’ EQUITY (UNAUDITED)

Nine Months Ended September 30, 2025

|  | Common Shares Outstanding 1 |  |  | Common Stock |  |  | Additional Paid in Capital |  |  | Retained Earnings |  |  | Treasury Stock |  |  | AOCI |  |  | Total |
|  | (In millions of dollars, except share and per share amounts) |
BALANCE, December 31, 2024, as adjusted 2 |  |  | 16,095,898 |  |  | $ | 0.2 |  |  | $ | 1,117.0 |  |  | $ | 81.3 |  |  | $ | (475.9 | ) |  | $ | 20.5 |  |  | $ | 743.1 |
Net income |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 21.6 |  |  |  | — |  |  |  | — |  |  |  | 21.6 |
Other comprehensive income, net of tax |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 2.6 |  |  |  | 2.6 |
Common shares issued (including impacts from Long-Term Incentive programs) |  |  | 84,115 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |
Cancellation of shares to cover tax withholdings upon common shares issued |  |  | (25,637 | ) |  |  | — |  |  |  | (1.8 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (1.8 | )
Cash dividends declared 3 |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (12.9 | ) |  |  | — |  |  |  | — |  |  |  | (12.9 | )
Amortization of unearned equity compensation |  |  | — |  |  |  | — |  |  |  | 4.2 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 4.2 |
BALANCE, March 31, 2025 |  |  | 16,154,376 |  |  | $ | 0.2 |  |  | $ | 1,119.4 |  |  | $ | 90.0 |  |  | $ | (475.9 | ) |  | $ | 23.1 |  |  | $ | 756.8 |
Net income |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 23.2 |  |  |  | — |  |  |  | — |  |  |  | 23.2 |
Other comprehensive income, net of tax |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 4.1 |  |  |  | 4.1 |
Common shares issued (including impacts from Long-Term Incentive programs) |  |  | 23,582 |  |  |  | — |  |  |  | 0.4 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.4 |
Cancellation of shares to cover tax withholdings upon common shares issued |  |  | (219 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |
Cash dividends declared 2 |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (12.8 | ) |  |  | — |  |  |  | — |  |  |  | (12.8 | )
Amortization of unearned equity compensation |  |  | — |  |  |  | — |  |  |  | 4.3 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 4.3 |
BALANCE, June 30, 2025 |  |  | 16,177,739 |  |  | $ | 0.2 |  |  | $ | 1,124.1 |  |  | $ | 100.4 |  |  | $ | (475.9 | ) |  | $ | 27.2 |  |  | $ | 776.0 |
Net income |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 39.5 |  |  |  | — |  |  |  | — |  |  |  | 39.5 |
Other comprehensive loss, net of tax |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (0.5 | ) |  |  | (0.5 | )
Common shares issued (including impacts from Long-Term Incentive programs) |  |  | 42,894 |  |  |  | — |  |  |  | 0.1 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.1 |
Cancellation of shares to cover tax withholdings upon common shares issued |  |  | (14,378 | ) |  |  | — |  |  |  | (1.1 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (1.1 | )
Cash dividends declared 2 |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (12.8 | ) |  |  | — |  |  |  | — |  |  |  | (12.8 | )
Amortization of unearned equity compensation |  |  | — |  |  |  | — |  |  |  | 4.9 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 4.9 |
BALANCE, September 30, 2025 |  |  | 16,206,255 |  |  | $ | 0.2 |  |  | $ | 1,128.0 |  |  | $ | 127.1 |  |  | $ | (475.9 | ) |  | $ | 26.7 |  |  | $ | 806.1 |

1.
At September 30, 2025, 449,765 shares were available for awards under the Kaiser Aluminum Corporation 2021 Equity and Incentive Compensation Plan, as amended and restated.
2.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
3.
Dividends declared per common share were $0.77 for each of the quarters ended March 31, 2025, June 30, 2025, and September 30, 2025.

The accompanying notes to interim consolidated financial statements are an integral part of these statements.

4

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

STATEMENTS OF CONSOLIDATED STOCKHOLDERS’ EQUITY CONTINUED (UNAUDITED)

Nine Months Ended September 30, 2024

|  | Common Shares Outstanding |  |  | Common Stock |  |  | Additional Paid in Capital |  |  | Retained Earnings As Adjusted 1 |  |  | Treasury Stock |  |  | AOCI |  |  | Total As Adjusted 1 |
|  | (In millions of dollars, except share and per share amounts) |
BALANCE, December 31, 2023 |  |  | 16,015,791 |  |  | $ | 0.2 |  |  | $ | 1,104.7 |  |  | $ | 10.1 |  |  | $ | (475.9 | ) |  | $ | 13.1 |  |  | $ | 652.2 |
Cumulative effect of change in inventory valuation methodology, net of tax |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 56.2 |  |  |  | — |  |  |  | — |  |  |  | 56.2 |
Net income |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 18.2 |  |  |  | — |  |  |  | — |  |  |  | 18.2 |
Other comprehensive loss, net of tax |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (2.1 | ) |  |  | (2.1 | )
Common shares issued (including impacts from Long-Term Incentive programs) |  |  | 56,416 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |
Cancellation of shares to cover tax withholdings upon common shares issued |  |  | (16,175 | ) |  |  | — |  |  |  | (1.2 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (1.2 | )
Cash dividends declared 2 |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (12.6 | ) |  |  | — |  |  |  | — |  |  |  | (12.6 | )
Amortization of unearned equity compensation |  |  | — |  |  |  | — |  |  |  | 4.0 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 4.0 |
BALANCE, March 31, 2024, as adjusted 1 |  |  | 16,056,032 |  |  | $ | 0.2 |  |  | $ | 1,107.5 |  |  | $ | 71.9 |  |  | $ | (475.9 | ) |  | $ | 11.0 |  |  | $ | 714.7 |
Net income |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 18.9 |  |  |  | — |  |  |  | — |  |  |  | 18.9 |
Other comprehensive income, net of tax |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 3.2 |  |  |  | 3.2 |
Common shares issued (including impacts from Long-Term Incentive programs) |  |  | 38,143 |  |  |  | — |  |  |  | 0.5 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.5 |
Cancellation of shares to cover tax withholdings upon common shares issued |  |  | (7,063 | ) |  |  | — |  |  |  | (0.6 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (0.6 | )
Cash dividends declared 1 |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (12.7 | ) |  |  | — |  |  |  | — |  |  |  | (12.7 | )
Amortization of unearned equity compensation |  |  | — |  |  |  | — |  |  |  | 3.6 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 3.6 |
BALANCE, June 30, 2024, as adjusted 1 |  |  | 16,087,112 |  |  | $ | 0.2 |  |  | $ | 1,111.0 |  |  | $ | 78.1 |  |  | $ | (475.9 | ) |  | $ | 14.2 |  |  | $ | 727.6 |
Net income |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 8.8 |  |  |  | — |  |  |  | — |  |  |  | 8.8 |
Other comprehensive income, net of tax |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 2.1 |  |  |  | 2.1 |
Common shares issued (including impacts from Long-Term Incentive programs) |  |  | 1,000 |  |  |  | — |  |  |  | 0.1 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.1 |
Cancellation of shares to cover tax withholdings upon common shares issued |  |  | (357 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |
Cash dividends declared 1 |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (12.7 | ) |  |  | — |  |  |  | — |  |  |  | (12.7 | )
Amortization of unearned equity compensation |  |  | — |  |  |  | — |  |  |  | 3.5 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 3.5 |
BALANCE, September 30, 2024 |  |  | 16,087,755 |  |  | $ | 0.2 |  |  | $ | 1,114.6 |  |  | $ | 74.2 |  |  | $ | (475.9 | ) |  | $ | 16.3 |  |  | $ | 729.4 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
2.
Dividends declared per common share were $0.77 for each of the quarters ended March 31, 2024, June 30, 2024, and September 30, 2024.

The accompanying notes to interim consolidated financial statements are an integral part of these statements.

5

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

STATEMENTS OF CONSOLIDATE D CASH FLOWS (UNAUDITED)

|  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |
|  | (In millions of dollars) |
Cash flows from operating activities 2: |  |  |  |  |  |
Net income |  | $ | 84.3 |  |  | $ | 45.9 |
Adjustments to reconcile net income to net cash provided by operating activities: |  |  |  |  |  |
Depreciation of property, plant and equipment |  |  | 88.2 |  |  |  | 83.4 |
Amortization of definite-lived intangible assets |  |  | 3.4 |  |  |  | 3.4 |
Amortization of debt premium and debt issuance costs |  |  | 1.7 |  |  |  | 1.8 |
Deferred income taxes |  |  | 21.2 |  |  |  | 10.4 |
Non-cash equity compensation |  |  | 13.9 |  |  |  | 11.7 |
Non-cash asset impairment charge 3 |  |  | — |  |  |  | 3.6 |
Non-cash unrealized loss on derivative positions |  |  | — |  |  |  | 2.2 |
Gain on disposition of property, plant and equipment |  |  | (9.1 | ) |  |  | (3.7 | )
Bad debt expense |  |  | 0.3 |  |  |  | 0.3 |
Non-cash postretirement and postemployment defined benefit plan cost |  |  | 7.1 |  |  |  | 6.8 |
Changes in operating assets and liabilities: |  |  |  |  |  |
Trade and other receivables |  |  | (79.7 | ) |  |  | (33.7 | )
Contract assets |  |  | 19.4 |  |  |  | (3.5 | )
Inventories |  |  | (100.4 | ) |  |  | (8.0 | )
Prepaid expenses and other current assets |  |  | (3.4 | ) |  |  | (5.6 | )
Accounts payable |  |  | 122.3 |  |  |  | 17.5 |
Accrued liabilities |  |  | (28.3 | ) |  |  | (11.6 | )
Annual variable cash contributions to Salaried VEBA |  |  | (0.7 | ) |  |  | (1.1 | )
Long-term assets and liabilities, net |  |  | (8.2 | ) |  |  | 3.9 |
Net cash provided by operating activities |  |  | 132.0 |  |  |  | 123.7 |
Cash flows from investing activities 2: |  |  |  |  |  |
Capital expenditures |  |  | (106.4 | ) |  |  | (124.8 | )
Purchase of equity securities |  |  | (0.4 | ) |  |  | (0.1 | )
Proceeds from sale of equity securities |  |  | 6.4 |  |  |  | 0.3 |
Proceeds from disposition of property, plant and equipment |  |  | 10.7 |  |  |  | 6.0 |
Net cash used in investing activities |  |  | (89.7 | ) |  |  | (118.6 | )
Cash flows from financing activities 2: |  |  |  |  |  |
Borrowings under the Revolving Credit Facility |  |  | 290.4 |  |  |  | — |
Repayment of borrowings under the Revolving Credit Facility |  |  | (290.4 | ) |  |  | — |
Repayment of finance lease |  |  | (1.8 | ) |  |  | (2.0 | )
Cancellation of shares to cover tax withholdings upon common shares issued |  |  | (2.9 | ) |  |  | (1.8 | )
Cash dividends and dividend equivalents paid |  |  | (38.5 | ) |  |  | (38.0 | )
Net cash used in financing activities |  |  | (43.2 | ) |  |  | (41.8 | )
Net decrease in cash, cash equivalents and restricted cash during the period |  |  | (0.9 | ) |  |  | (36.7 | )
Cash, cash equivalents and restricted cash at beginning of period |  |  | 37.9 |  |  |  | 100.7 |
Cash, cash equivalents and restricted cash at end of period |  | $ | 37.0 |  |  | $ | 64.0 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
2.
See Note 12 for supplemental cash flow information.
3.
Non-cash asset impairment charge for the nine months ended September 30, 2024 is comprised of: (i) a $3.2 million inventory write-down related to certain alloying metals and (ii) a $0.4 million impairment charge on land held for sale.

The accompanying notes to interim consolidated financial statements are an integral part of these statements.

6

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS - UNAUDITED

NOTES INDEX

Note 1 |  | Basis of Presentation and Recent Accounting Pronouncements | 8
Note 2 |  | Supplemental Balance Sheet Information | 10
Note 3 |  | Employee Benefits | 11
Note 4 |  | Restructuring | 12
Note 5 |  | Derivatives, Hedging Programs and Other Financial Instruments | 13
Note 6 |  | Debt and Credit Facility | 16
Note 7 |  | Commitments and Contingencies | 18
Note 8 |  | Accumulated Other Comprehensive Income | 19
Note 9 |  | Other Income, Net | 20
Note 10 |  | Income Tax Matters | 20
Note 11 |  | Earnings Per Share | 21
Note 12 |  | Supplemental Cash Flow Information | 22
Note 13 |  | Business, Product, and Geographical Area Information | 22
Note 14 |  | Change in Accounting Principle | 24
Note 15 |  | Subsequent Events | 26

7

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

1. Basis of Presentation and Recent Accounting Pronouncements

This Form 10-Q should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2024. Unless the context otherwise requires, references in these notes to interim consolidated financial statements - unaudited to “Kaiser,” “we,” “us,” “our,” “the Company” and “our Company” refer collectively to Kaiser Aluminum Corporation and its subsidiaries.

Principles of Consolidation and Basis of Presentation. The accompanying unaudited consolidated financial statements include the accounts of our wholly owned subsidiaries and are prepared in accordance with GAAP and the rules and regulations of the SEC applicable for interim periods and, therefore, do not include all information and footnotes required by GAAP for complete financial statements. In management’s opinion, all adjustments (which include normal recurring adjustments) considered necessary for a fair presentation have been included. We have reclassified certain items in prior periods to conform to current classifications. The results of operations for our interim periods are not necessarily indicative of the results of operations that may be achieved for the entire 2025 fiscal year. The financial information as of December 31, 2024 is derived from our audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2024, except for the change in accounting principle disclosed in Note 14 of Notes to Interim Consolidated Financial Statements included in this Report.

Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of our consolidated financial statemen ts; accordingly, it is possible that the actual results could differ from these estimates and assumptions, which could have a material effect on the reported amounts of our consolidated financial position and results of operations.

Change in Accounting Principle. Effective January 1, 2025, the Company changed its inventory valuation methodology from LIFO to WAC for its finished products, work-in-process, and raw material inventories. This change is preferable because the Company believes that it improves the comparability of the Company's operational results between periods by removing LIFO income or charge in a period resulting from LIFO valuation and changes to historical LIFO layers. Additionally, the Company believes that the new valuation methodology better reflects the physical flow of goods and simplifies the financial close process by utilizing the WAC valuation methodology for all internal and external reporting purposes. The effects of this change have been retrospectively applied to all prior periods presented. See Note 14 for additional information regarding the change in inventory valuation methodology.

Accounting Pronouncements Issued But Not Yet Adopted

Disclosure Improvements. In October 2023, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2023-06 (“ASU 2023-06”), Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative. The guidance amends GAAP to reflect updates and simplifications to certain disclosure requirements referred to the FASB by the SEC. The amendments in ASU 2023-06 will become effective on the date which the SEC’s removal of the related disclosure becomes effective. If by June 30, 2027, the SEC does not remove the related disclosure, the pending amendment will be removed from ASC 2023-06 and it will not be effective. Adoption of ASU 2023-06 is expected to modify the disclosure and presentation requirements only and is not expected to have a material impact on our consolidated financial statements.

Income Taxes. In December 2023, the FASB issued ASU No. 2023-09 (“ASU 2023-09”), Improvements to Income Tax Disclosures. The guidance is intended to improve income tax disclosure requirements by requiring: (i) consistent categories and greater disaggregation of information in the rate reconciliation and (ii) the disaggregation of income taxes paid by jurisdiction. The guidance makes several other changes to the annual income tax disclosure requirements. The amendments in ASU 2023-09 are effective for fiscal years beginning after December 15, 2024, with early adoption permitted, and is required to be applied prospectively with the option of retrospective application. We plan to adopt the provisions of ASU 2023-09 prospectively in the fourth quarter of fiscal 2025 and do not expect this ASU to have a material impact on our consolidated financial statements.

Disaggregation of Income Statement Expenses. In November 2024, the FASB issued ASU No. 2024-03 (“ASU 2024-03”), Disaggregation of Income Statement Expenses. The guidance requires additional, disaggregated disclosure about certain income statement expense line items. The amendments in ASU 2024-03 are effective for annual reporting periods beginning after December

8

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

15, 2026 and interim reporting periods beginning after December 15, 2027, with early adoption permitted, and is required to be applied prospectively with the option of retrospective application. We plan to adopt the provisions of ASU 2024-03 prospectively in the fourth quarter of fiscal 2027 and continue to evaluate the disclosure requirements related to the new standard.

Credit Losses for Accounts Receivable and Contract Assets. In July 2025, the FASB issued ASU No. 2025-05 (“ASU 2025-05”), Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets, which provides entities with a practical expedient to simplify the estimation of expected credit losses by assuming that the current conditions as of the balance sheet date will not change for the remaining life of the asset. ASU 2025-05 is effective for fiscal years beginning after December 15, 2025 and interim reporting periods within those annual reporting periods, with early adoption permitted, and should be applied prospectively. We are currently in the process of evaluating the effects of this pronouncement on our consolidated financial statements.

Accounting for Internal-Use Software. In September 2025, the FASB issued ASU No. 2025-06 (“ASU 2025-06”), Intangibles - Goodwill and Other - Internal-Use Software (Subto pic 350-40): Targeted Improvements to the Accounting for Internal-Use Software, which improves the operability of the guidance by removing all references to software development stages so that the guidance is neutral to different software development methods. ASU 2025-06 is effective for fiscal years beginning after December 15, 2027 and interim reporting periods within those annual reporting periods, with early adoption permitted as of the beginning of the annual reporting period. The amendments may be applied by using a prospective transition approach, a retrospective transition approach, or a modified transition approach based on the status of the project and whether software costs were capitalized before the date of adoption. We are currently in the process of evaluating the effects of this pronouncement on our consolidated financial statements.

9

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

2. Supplemental Balance Sheet Information

|  | As of September 30, 2025 |  |  | As of December 31, 2024 As Adjusted 1 |
|  | (In millions of dollars) |
Trade Receivables, Net |  |  |  |  |  |
Billed trade receivables |  | $ | 389.5 |  |  | $ | 320.5 |
Allowance for doubtful receivables |  |  | (0.6 | ) |  |  | (0.8 | )
Trade receivables, net |  | $ | 388.9 |  |  | $ | 319.7 |
Inventories |  |  |  |  |  |
Finished products |  | $ | 144.1 |  |  | $ | 130.0 |
Work-in-process |  |  | 296.0 |  |  |  | 229.1 |
Raw materials |  |  | 246.8 |  |  |  | 228.7 |
Operating supplies |  |  | 15.4 |  |  |  | 14.1 |
Inventories |  | $ | 702.3 |  |  | $ | 601.9 |
Property, Plant and Equipment, Net |  |  |  |  |  |
Land and improvements |  | $ | 38.7 |  |  | $ | 37.2 |
Buildings and leasehold improvements |  |  | 320.9 |  |  |  | 256.3 |
Machinery and equipment 2 |  |  | 1,562.9 |  |  |  | 1,337.4 |
Construction in progress |  |  | 128.7 |  |  |  | 297.5 |
Property, plant and equipment, gross |  |  | 2,051.2 |  |  |  | 1,928.4 |
Accumulated depreciation and amortization |  |  | (851.5 | ) |  |  | (767.5 | )
Land held for sale |  |  | 0.1 |  |  |  | 0.3 |
Property, plant and equipment, net |  | $ | 1,199.8 |  |  | $ | 1,161.2 |
Other Assets |  |  |  |  |  |
Assets to be conveyed associated with Warrick acquisition 2 |  | $ | — |  |  | $ | 18.3 |
Restricted cash – Note 12 |  |  | 19.8 |  |  |  | 19.5 |
Long-term replacement parts |  |  | 25.5 |  |  |  | 18.3 |
Other |  |  | 16.4 |  |  |  | 22.5 |
Other assets |  | $ | 61.7 |  |  | $ | 78.6 |
Other Accrued Liabilities |  |  |  |  |  |
Uncleared cash disbursements |  | $ | 1.4 |  |  | $ | 24.5 |
Accrued income taxes and other taxes payable |  |  | 11.5 |  |  |  | 11.1 |
Accrued annual contribution to Salaried VEBA |  |  | — |  |  |  | 0.7 |
Accrued interest |  |  | 10.5 |  |  |  | 9.9 |
Short-term environmental accrual – Note 7 |  |  | 0.7 |  |  |  | 0.7 |
Current operating lease liabilities |  |  | 5.3 |  |  |  | 6.3 |
Current finance lease liabilities |  |  | 2.4 |  |  |  | 2.4 |
Current deferred compensation plan liabilities – Note 3 |  |  | 0.4 |  |  |  | 6.7 |
Other – Note 5 |  |  | 17.3 |  |  |  | 17.0 |
Other accrued liabilities |  | $ | 49.5 |  |  | $ | 79.3 |
Long-Term Liabilities |  |  |  |  |  |
Workers' compensation accrual |  | $ | 27.7 |  |  | $ | 26.8 |
Long-term environmental accrual – Note 7 |  |  | 17.5 |  |  |  | 17.7 |
Other long-term liabilities |  |  | 39.2 |  |  |  | 39.5 |
Long-term liabilities |  | $ | 84.4 |  |  | $ | 84.0 |

10

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
2.
During the quarter ended March 31, 2025, $18.3 million of certain assets associated with our acquisition of Warrick were conveyed to us and placed in service. At September 30, 2025, such assets are presented within Machinery and equipment.

3. Employee Benefits

Deferred Compensation Plan

Assets of our deferred compensation plan are included in Other assets, classified within Level 1 of the fair value hierarchy and are measured and recorded at fair value based on their quoted market prices. The following table presents the fair value of these assets (in millions of dollars):

|  | As of September 30, 2025 |  |  | As of December 31, 2024 |
Deferred compensation program - Diversified investment funds in registered investment companies |  | $ | 6.6 |  |  | $ | 11.9 |

Assets in the trust are accounted for as equity investments with changes in fair value recorded within Other income, net (see Note 9). Offsetting liabilities relating to the deferred compensation plan are included in Other accrued liabilities and Long-term liabilities.

Short-Term Incentive Plans

As of September 30, 2025, we had a liability of $20.0 million recorded within Accrued salaries, wages and related expenses for estimated probable future payments under the 2025 short-term incentive plans.

Postretirement and Postemployment Benefit Plans

The following table presents the total expense related to all postretirement and postemployment benefit plans (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Defined contribution plans 1 |  | $ | 4.2 |  |  | $ | 4.4 |  |  | $ | 14.8 |  |  | $ | 14.4 |
Deferred compensation plan 2 |  |  | 0.5 |  |  |  | 0.5 |  |  |  | 1.1 |  |  |  | 1.2 |
Multiemployer pension plans 1 |  |  | 1.6 |  |  |  | 1.6 |  |  |  | 4.7 |  |  |  | 4.6 |
Net periodic postretirement and postemployment benefit cost relating to defined benefit plans 2,3 |  |  | 2.3 |  |  |  | 2.5 |  |  |  | 7.1 |  |  |  | 6.8 |
Total |  | $ | 8.6 |  |  | $ | 9.0 |  |  | $ | 27.7 |  |  | $ | 27.0 |

1.
Substantially all of these charges related to employee benefits are in COGS with the remaining balance in Selling, general, administrative, research, and development (“SG&A and R&D”) within our Statements of Consolidated Income. For the nine months ended September 30, 2024, the expense presented for our multiemployer pension plans excludes a $4.6 million charge to Restructuring costs (see Note 4).
2.
Deferred compensation plan expense and the current service cost component of Net periodic postretirement and postemployment benefit cost relating to Salaried VEBA are included within our Statements of Consolidated Income in SG&A and R&D for all periods presented. All other components of Net periodic postretirement and postemployment benefit cost relating to Salaried VEBA are included within Other income, net, on our Statements of Consolidated Income.
3.
The current service cost component of Net periodic postretirement and postemployment benefit cost relating to both the pension plans and the OPEB plan is included within our Statements of Consolidated Income in COGS for all periods presented. All other components of Net periodic postretirement and postemployment benefit cost relating to both the pension plans and the OPEB plan are included within Other income, net, on our Statements of Consolidated Income.

11

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

Components of Net Periodic Postretirement and Postemployment Benefit Cost. The following tables present the components of Net periodic postretirement and postemployment benefit cost relating to our defined benefit plans (in millions of dollars):

|  | Pension Plans |  |  | OPEB |  |  | Salaried VEBA |
|  | Quarter Ended |  |  | Quarter Ended |  |  | Quarter Ended |
|  | September 30, |  |  | September 30, |  |  | September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Service cost |  | $ | 0.9 |  |  | $ | 0.7 |  |  | $ | 0.2 |  |  | $ | 0.3 |  |  | $ | — |  |  | $ | — |
Interest cost |  |  | 0.4 |  |  |  | 0.4 |  |  |  | 0.9 |  |  |  | 0.8 |  |  |  | 0.6 |  |  |  | 0.5 |
Expected return on plan assets |  |  | (0.4 | ) |  |  | (0.3 | ) |  |  | — |  |  |  | — |  |  |  | (0.6 | ) |  |  | (0.6 | )
Amortization of prior service cost 1 |  |  | 0.3 |  |  |  | 0.2 |  |  |  | — |  |  |  | — |  |  |  | 0.7 |  |  |  | 0.8 |
Amortization of net actuarial gain |  |  | (0.1 | ) |  |  | — |  |  |  | (0.5 | ) |  |  | (0.3 | ) |  |  | (0.1 | ) |  |  | — |
Total net periodic postretirement and postemployment benefit cost |  | $ | 1.1 |  |  | $ | 1.0 |  |  | $ | 0.6 |  |  | $ | 0.8 |  |  | $ | 0.6 |  |  | $ | 0.7 |

|  | Pension Plans |  |  | OPEB |  |  | Salaried VEBA |
|  | Nine Months Ended |  |  | Nine Months Ended |  |  | Nine Months Ended |
|  | September 30, |  |  | September 30, |  |  | September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Service cost |  | $ | 2.6 |  |  | $ | 2.7 |  |  | $ | 0.7 |  |  | $ | 0.8 |  |  | $ | — |  |  | $ | — |
Interest cost |  |  | 1.2 |  |  |  | 1.2 |  |  |  | 2.6 |  |  |  | 2.5 |  |  |  | 1.7 |  |  |  | 1.6 |
Expected return on plan assets |  |  | (1.1 | ) |  |  | (1.0 | ) |  |  | — |  |  |  | — |  |  |  | (1.7 | ) |  |  | (1.7 | )
Amortization of prior service cost 1 |  |  | 0.7 |  |  |  | 0.5 |  |  |  | — |  |  |  | — |  |  |  | 2.2 |  |  |  | 1.0 |
Amortization of net actuarial gain |  |  | (0.1 | ) |  |  | — |  |  |  | (1.4 | ) |  |  | (0.8 | ) |  |  | (0.3 | ) |  |  | — |
Total net periodic postretirement and postemployment benefit cost |  | $ | 3.3 |  |  | $ | 3.4 |  |  | $ | 1.9 |  |  | $ | 2.5 |  |  | $ | 1.9 |  |  | $ | 0.9 |

1.
We amortize prior service cost on a straight-line basis over the average remaining years of service of the active plan participants.

Pension Plan Contributions. During the nine months ended September 30, 2025, we contributed $4.6 million to our pension plans. We expect to make additional contributions of approximately $1.6 million to the pension plans during the remainder of 2025.

4. Restructuring

2025 Restructuring Plan. During the quarter ended March 31, 2025, we initiated a plan to reduce certain operating costs (“2025 Restructuring Plan”). Through September 30, 2025, we have recorded a charge of $1.9 million for severance and related benefits. Substantially all of the costs associated with the restructuring efforts initiated under the 2025 Restructuring Plan were incurred and expensed as of September 30, 2025. The costs are recorded within Restructuring costs in our Statements of Consolidated Income.

The following table summarizes activity relating to the 2025 Restructuring Plan liabilities (in millions of dollars):

BALANCE, December 31, 2024 |  | $ | — |
Restructuring costs |  |  | 1.8 |
Costs paid or otherwise settled 1 |  |  | (1.3 | )
BALANCE, March 31, 2025 |  |  | 0.5 |
Restructuring costs |  |  | 0.1 |
Costs paid or otherwise settled 1 |  |  | (0.4 | )
BALANCE, June 30, 2025 |  | $ | 0.2 |
Restructuring costs |  |  | — |
Costs paid or otherwise settled 1 |  |  | (0.1 | )
BALANCE, September 30, 2025 |  | $ | 0.1 |

1.
Cash paid during the quarter and nine months ended September 30, 2025 w as $0.1 million and $1.8 million, respectively.

12

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

2024 Restructuring Plan. During the quarter ended June 30, 2024, we initiated a plan to exit our soft alloy aluminum extrusion facility located in Sherman, Texas (“2024 Restructuring Plan”). Through September 30, 2025, we have recorded a charge of $7.5 million, consisting of a $4.6 million multiemployer pension obligation which is expected to be paid in 2027 and a $2.9 million charge for severance, related benefits, and other costs. Substantially all of the costs associated with the restructuring efforts initiated under the 2024 Restructuring Plan were incurred and expensed as of December 31, 2024. The costs are recorded within Restructuring costs in our Statements of Consolidated Income.

The following table summarizes activity relating to the 2024 Restructuring Plan liabilities (in millions of dollars):

BALANCE, December 31, 2024 |  | $ | 4.7 |
Restructuring costs |  |  | — |
Costs paid or otherwise settled 1 |  |  | (0.1 | )
BALANCE, March 31, 2025 |  |  | 4.6 |
Restructuring costs |  |  | — |
Costs paid or otherwise settled 1 |  |  | — |
BALANCE, June 30, 2025 |  | $ | 4.6 |
Restructuring costs |  |  | — |
Costs paid or otherwise settled 1 |  |  | — |
BALANCE, September 30, 2025 |  | $ | 4.6 |

1.
Cash paid during the quarter and nine months ended September 30, 2025 was $0.0 million and $0.1 million, respectively.

5. Derivatives, Hedging Programs and Other Financial Instruments

Overview

We utilize derivative instruments to manage exposure to: (i) metal price risk related to aluminum and certain alloys used as raw material for our fabrication operations; (ii) energy price risk related to natural gas and electricity used in our production processes; and (iii) foreign currency exchange rate risk related to certain equipment and service agreements. We do not use derivative financial instruments for trading or other speculative purposes. All hedging transactions are executed centrally and are overseen by a committee (“Hedging Committee”) composed of key operations and finance personnel from the management team. The scope of the Hedging Committee’s activities is reviewed with our Board of Directors.

We are exposed to counterparty credit risk on all of our derivative instruments. Our counterparties are major investment-grade financial institutions or trading companies, and our hedging transactions are governed by negotiated International Swaps and Derivatives Association Master Agreements, which generally require collateral to be posted by our counterparties above specified credit thresholds, which may adjust up or down based on changes credit ratings. As a result, we believe the risk of loss is remote and contained. The aggregate fair value of our derivative instruments that were in a net liability position was $0.1 million and $0.8 million at September 30, 2025 and December 31, 2024, respectively. We had no collateral posted as of those dates.

In addition, our firm-price customer sales commitments create incremental customer credit risk related to metal price movements. Under certain circumstances, we mitigate this risk by periodically requiring cash collateral to be posted by our customers, which we classify as deferred revenue and include as a component of Other accrued liabilities. We had no cash collateral posted by our customers at both September 30, 2025 and December 31, 2024.

The above described derivative instruments are typically designated as cash flow hedges. Unrealized gains and losses associated with our cash flow hedges are deferred in Other comprehensive income, net of tax, and reclassified to COGS when such hedges settle or when it is probable that the original forecasted transactions will not occur by the end of the originally specified time period. See Note 8 for the total amount of gain or loss on derivative instruments designated and qualifying as cash flow hedging instruments that was reported in AOCI, as well as the related reclassifications into earnings and tax effects. Cumulative gains and losses related to cash flow hedges are reclassified out of AOCI and recorded within COGS when the associated hedged commodity purchases impact earnings.

From time to time, we enter into commodity and foreign currency forward contracts that are not designated as hedging instruments to mitigate certain short‑term impacts, as identified. The gain or loss on these commodity and foreign currency derivatives is recognized

13

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

within COGS and Other income, net, respectively. As of September 30, 2025 and December 31, 2024, we had no outstanding non-designated derivative hedge positions.

Notional Amount of Derivative Contracts

The following table summarizes our derivative positions at September 30, 2025:

Aluminum |  | Maturity Period |  | Notional Amount of Contracts (mmlbs) |
Fixed price purchase contracts for LME |  | October 2025 through November 2026 |  |  | 64.1 |
Fixed price sale contracts for LME |  | October 2025 through March 2026 |  |  | 23.5 |
Fixed price purchase contracts for MWTP |  | October 2025 through November 2026 |  |  | 64.1 |
Fixed price sale contracts for MWTP |  | October 2025 through April 2026 |  |  | 23.5 |

Alloying Metals |  | Maturity Period |  | Notional Amount of Contracts (mmlbs) |
Fixed price purchase contracts |  | October 2025 through December 2027 |  |  | 6.8 |

Natural Gas |  | Maturity Period |  | Notional Amount of Contracts (mmbtu) |
Fixed price purchase contracts |  | October 2025 through December 2027 |  |  | 3,300,000 |

Euro |  | Maturity Period |  | Notional Amount of Contracts (in millions of Euros) |
Fixed price forward purchase contracts |  | October 2025 through July 2027 |  | € | 1.7 |

14

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

(Gain) Loss on Derivative Contracts

The following table summarizes the amount of (gain) loss on derivative contracts recorded within our Statements of Consolidated Income in COGS (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |  |  | 2025 |  |  | 2024 As Adjusted 1 |
Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of hedges are recorded: |  |  |  |  |  |  |  |  |  |  |  |
Cash flow hedges |  | $ | 728.8 |  |  | $ | 676.0 |  |  | $ | 2,125.0 |  |  | $ | 1,997.1 |
(Gain) loss recognized in our Statements of Consolidated Income related to cash flow hedges: |  |  |  |  |  |  |  |  |  |  |  |
Aluminum |  | $ | (9.7 | ) |  | $ | 1.6 |  |  | $ | (17.1 | ) |  | $ | 0.9 |
Alloying Metals |  |  | (0.5 | ) |  |  | (0.3 | ) |  |  | (1.4 | ) |  |  | (0.8 | )
Natural gas |  |  | 0.4 |  |  |  | 0.3 |  |  |  | 0.7 |  |  |  | 1.0 |
Electricity |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.6 |
Foreign exchange contracts |  |  | (0.2 | ) |  |  | (0.1 | ) |  |  | (0.2 | ) |  |  | (0.1 | )
Total (gain) loss recognized in our Statements of Consolidated Income related to cash flow hedges |  | $ | (10.0 | ) |  | $ | 1.5 |  |  | $ | (18.0 | ) |  | $ | 1.6 |
Loss recognized in our Statements of Consolidated Income related to non-designated derivatives: |  |  |  |  |  |  |  |  |  |  |  |
Electricity – Realized loss |  |  | — |  |  |  | 2.0 |  |  |  | — |  |  |  | 2.0 |
Electricity – Unrealized mark-to-market loss |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 2.0 |
Electricity (reclassification from AOCI due to forecasted transactions probable of not occurring) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.2 |
Total loss recognized in our Statements of Consolidated Income related to non-designated derivatives |  | $ | — |  |  | $ | 2.0 |  |  | $ | — |  |  | $ | 4.2 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.

Fair Values of Derivative Contracts

The fair values of our derivative contracts are based upon trades in liquid markets. Valuation model inputs can be verified, and valuation techniques do not involve significant judgment. The fair values of such derivatives are classified within Level 2 of the fair value hierarchy.

15

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

All of our derivative contracts with counterparties are subject to enforceable master netting arrangements. We reflect the fair value of our derivative contracts on a gross basis on our Consolidated Balance Sheets. The following table presents the fair value of our derivative assets and liabilities (in millions of dollars):

|  | As of September 30, 2025 |  |  | As of December 31, 2024 |
|  | Assets |  |  | Liabilities |  |  | Net Amount |  |  | Assets |  |  | Liabilities |  |  | Net Amount |
Cash Flow Hedges: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aluminum – |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed price purchase contracts for LME |  | $ | 1.8 |  |  | $ | — |  |  | $ | 1.8 |  |  | $ | 1.1 |  |  | $ | (0.8 | ) |  | $ | 0.3 |
Fixed price sale contracts for LME |  |  | — |  |  |  | (0.5 | ) |  |  | (0.5 | ) |  |  | — |  |  |  | — |  |  |  | — |
Fixed price purchase contracts for MWTP |  |  | 7.8 |  |  |  | — |  |  |  | 7.8 |  |  |  | 1.1 |  |  |  | — |  |  |  | 1.1 |
Fixed price sale contracts for MWTP |  |  | — |  |  |  | (1.2 | ) |  |  | (1.2 | ) |  |  | — |  |  |  | — |  |  |  | — |
Alloying Metals – Fixed price purchase contracts |  |  | 1.2 |  |  |  | (0.1 | ) |  |  | 1.1 |  |  |  | 1.3 |  |  |  | (0.1 | ) |  |  | 1.2 |
Natural gas – Fixed price purchase contracts |  |  | 1.0 |  |  |  | (1.0 | ) |  |  | — |  |  |  | 0.5 |  |  |  | (0.8 | ) |  |  | (0.3 | )
Foreign currency – Fixed price forward contracts |  |  | 0.1 |  |  |  | — |  |  |  | 0.1 |  |  |  | — |  |  |  | (0.4 | ) |  |  | (0.4 | )
Total |  | $ | 11.9 |  |  | $ | (2.8 | ) |  | $ | 9.1 |  |  | $ | 4.0 |  |  | $ | (2.1 | ) |  | $ | 1.9 |

The following table presents the total amounts of derivative assets and liabilities on our Consolidated Balance Sheets (in millions of dollars):

|  | As of September 30, 2025 |  |  | As of December 31, 2024 |
Derivative assets: |  |  |  |  |  |
Prepaid expenses and other current assets |  | $ | 10.8 |  |  | $ | 3.7 |
Other assets |  |  | 1.1 |  |  |  | 0.3 |
Total derivative assets |  | $ | 11.9 |  |  | $ | 4.0 |
Derivative liabilities: |  |  |  |  |  |
Other accrued liabilities |  | $ | (2.2 | ) |  | $ | (1.8 | )
Long-term liabilities |  |  | (0.6 | ) |  |  | (0.3 | )
Total derivative liabilities |  | $ | (2.8 | ) |  | $ | (2.1 | )

Fair Values of Other Financial Instruments

All Other Financial Assets and Liabilities. We believe that the carrying amounts of our accounts receivable, contract assets, accounts payable and accrued liabilities approximate their respective fair values due to their short-term nature and nominal credit risk.

6. Debt and Credit Facility

Senior Notes

At September 30, 2025 and December 31, 2024, we had outstanding fixed-rate unsecured Senior Notes with varying maturity dates. The stated interest rates and aggregate principal amounts of such Senior Notes were, respectively: (i) 4.625% and $500.0 million (“4.625% Senior Notes”) and (ii) 4.50% and $550.0 million (“4.50% Senior Notes”). Our Senior Notes do not require us to make any mandatory redemptions or sinking fund payments. The following table summarizes key details of our Senior Notes:

|  |  |  |  |  | Outstanding (in millions of dollars) |
|  | Issuance Date |  | Maturity |  | Effective Interest Rate |  | As of September 30, 2025 |  |  | As of December 31, 2024 |
4.625% Senior Notes |  | November 2019 |  | March 2028 |  | 4.8% |  | $ | 500.0 |  |  | $ | 500.0 |
4.50% Senior Notes |  | May 2021 |  | June 2031 |  | 4.7% |  |  | 550.0 |  |  |  | 550.0 |
Total debt |  |  |  |  |  |  |  |  | 1,050.0 |  |  |  | 1,050.0 |
Unamortized issuance costs |  |  |  |  |  |  |  |  | (7.1 | ) |  |  | (8.4 | )
Total carrying amount |  |  |  |  |  |  |  | $ | 1,042.9 |  |  | $ | 1,041.6 |

16

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

The following table presents the fair value of our outstanding Senior Notes, which are Level 1 liabilities (in millions of dollars):

|  |  |  |  |  | As of September 30, 2025 |  |  | As of December 31, 2024 |
4.625% Senior Notes |  |  |  |  |  | $ | 494.4 |  |  | $ | 470.1 |
4.50% Senior Notes |  |  |  |  |  | $ | 518.4 |  |  | $ | 484.8 |

Revolving Credit Facility

In October 2019, we entered into a Revolving Credit Facility. Joining us as borrowers under the Revolving Credit Facility are four of our wholly owned domestic operating subsidiaries: (i) Kaiser Aluminum Investments Company; (ii) Kaiser Aluminum Fabricated Products, LLC; (iii) Kaiser Aluminum Washington, LLC; and (iv) Kaiser Aluminum Warrick, LLC (collectively with the Company, the “Borrowers”). On October 14, 2025, we entered into amendment No. 5 to our Revolving Credit Facility. See Note 15, for details regarding the revised terms of the Revolving Credit Facility as amended.

The Revolving Credit Facility contains a maximum commitment amount of $575.0 million (of which up to a maximum of $50.0 million may be utilized for letters of credit) and, prior to the October 14, 2025 amendment, had a maturity date of April 2027. The amount we can borrow under our Revolving Credit Facility is determined by the value of our receivables and inventory, which serve as collateral for the facility. Our effective interest rate on outstanding borrowings under the amended Revolving Credit Facility is based on the rates of Base Rate Loans and SOFR Loans (as defined in the amended Revolving Credit Facility). As of September 30, 2025, the rate for Base Rate Loans was equal to the prevailing Prime Rate plus 0.25% (or, if borrowing availability was less than 40% of the maximum revolving commitments, 0.50%), while the rate for SOFR Loans, which are made for one or three month periods, was equal to the Term SOFR Reference Rate (as defined in the amended Revolving Credit Facility) plus 1.35% (or, if borrowing availability was less than 40% of the maximum revolving commitments, 1.60%). Outstanding borrowings under the Revolving Credit Facility are reported within Long-term debt, net, on our Consolidated Balance Sheets. We had no outstanding borrowings under the Revolving Credit Facility as of September 30, 2025 after repaying borrowings of $290.4 million incurred during the nine months ended September 30, 2025. We had no outstanding borrowings under the Revolving Credit Facility as of or during the year ended December 31, 2024.

The following table summarizes availability and usage of our Revolving Credit Facility as determined by a borrowing base calculated as of September 30, 2025 (in millions of dollars):

Revolving Credit Facility borrowing commitment |  | $ | 575.0 |
Borrowing base availability |  | $ | 575.0 |
Less: Outstanding borrowings under Revolving Credit Facility |  |  | — |
Less: Outstanding letters of credit under Revolving Credit Facility |  |  | (14.6 | )
Remaining borrowing availability |  | $ | 560.4 |

Interest Expense

The following table presents interest expense relating to our Senior Notes and Revolving Credit Facility (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Senior Notes interest expense, including debt issuance cost amortization |  | $ | 12.4 |  |  | $ | 12.4 |  |  | $ | 37.2 |  |  | $ | 37.2 |
Revolving Credit Facility interest expense, including commitment fees and finance cost amortization |  |  | 0.7 |  |  |  | 0.6 |  |  |  | 2.0 |  |  |  | 1.8 |
Interest expense on finance lease liabilities |  |  | 0.2 |  |  |  | 0.2 |  |  |  | 0.6 |  |  |  | 0.6 |
Interest expense capitalized as construction in progress |  |  | (0.9 | ) |  |  | (2.5 | ) |  |  | (3.7 | ) |  |  | (6.3 | )
Total interest expense |  | $ | 12.4 |  |  | $ | 10.7 |  |  | $ | 36.1 |  |  | $ | 33.3 |

17

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

7. Commitments and Contingencies

Commitments. We have a variety of financial commitments, including purchase agreements, forward foreign exchange and forward sales contracts, indebtedness and letters of credit (see Note 5 and Note 6).

Environmental Contingencies. We are subject to several environmental laws and regulations, potential fines or penalties assessed for alleged breaches of such laws and regulations, and potential claims based upon such laws and regulations. We are also subject to legacy environmental contingencies related to activities that occurred at our operating facilities prior to July 6, 2006, which represent the majority of our environmental accruals of $18.2 million as of September 30, 2025. This accrual represents our undiscounted estimate of costs reasonably expected to be incurred based on current laws and regulations, available facts, existing technologies, and our assessment of the likely remediation actions to be taken.

Based on approved and proposed remediation action plans for the various facilities, we expect that the implementation and ongoing monitoring could occur over a period of 30 or more years. As additional facts are developed, feasibility studies are completed, remediation plans are modified, necessary regulatory approvals for the implementation of remediation are obtained, alternative technologies are developed and/or other factors change, there may be revisions to management’s estimates, and actual costs may exceed the current environmental accruals by up to $14.2 million. Changes to our estimates may occur within the next 12 months as new information becomes available.

Other Contingencies. We are party to various lawsuits, claims, investigations and administrative proceedings that arise in connection with past and current operations. We evaluate such matters on a case-by-case basis and our policy is to vigorously contest any such claims we believe are without merit. We accrue for a legal liability when it is both probable that a liability has been incurred and the amount of the loss is reasonably estimable. Quarterly, in addition to when changes in facts and circumstances require it, we review and adjust these accruals to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular case. While uncertainties are inherent in the final outcome of such matters and it is presently impossible to determine the actual cost that may ultimately be incurred, we believe that we have sufficiently accrued for such matters and that the ultimate resolution of pending matters will not have a material impact on our consolidated financial position, operating results or liquidity.

18

Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

8. Accumulated Other Comprehensive Income

The following table presents the changes in the accumulated balances for each component of AOCI (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Defined Benefit Plans: |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  | $ | 19.6 |  |  | $ | 10.4 |  |  | $ | 19.1 |  |  | $ | 11.0 |
Actuarial (loss) gain arising during the period |  |  | — |  |  |  | — |  |  |  | (0.1 | ) |  |  | 1.4 |
Less: income tax expense |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (0.3 | )
Net actuarial (loss) gain arising during the period |  |  | — |  |  |  | — |  |  |  | (0.1 | ) |  |  | 1.1 |
Prior service cost arising during the period |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (2.2 | )
Less: income tax benefit |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.5 |
Net prior service cost arising during the period |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (1.7 | )
Amortization of net actuarial gain 1 |  |  | (0.7 | ) |  |  | (0.3 | ) |  |  | (1.8 | ) |  |  | (0.8 | )
Amortization of prior service cost 1 |  |  | 1.0 |  |  |  | 1.0 |  |  |  | 2.9 |  |  |  | 1.5 |
Less: income tax expense 2 |  |  | (0.1 | ) |  |  | (0.2 | ) |  |  | (0.3 | ) |  |  | (0.2 | )
Net amortization reclassified from AOCI to Net income |  |  | 0.2 |  |  |  | 0.5 |  |  |  | 0.8 |  |  |  | 0.5 |
Other comprehensive income (loss), net of tax |  |  | 0.2 |  |  |  | 0.5 |  |  |  | 0.7 |  |  |  | (0.1 | )
Ending balance |  | $ | 19.8 |  |  | $ | 10.9 |  |  | $ | 19.8 |  |  | $ | 10.9 |
Cash Flow Hedges: |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  | $ | 7.6 |  |  | $ | 3.8 |  |  | $ | 1.4 |  |  | $ | 2.1 |
Unrealized gain on cash flow hedges |  |  | 9.0 |  |  |  | 0.6 |  |  |  | 25.2 |  |  |  | 2.5 |
Less: income tax expense |  |  | (2.1 | ) |  |  | (0.2 | ) |  |  | (5.9 | ) |  |  | (0.6 | )
Net unrealized gain on cash flow hedges |  |  | 6.9 |  |  |  | 0.4 |  |  |  | 19.3 |  |  |  | 1.9 |
Reclassification of unrealized (gain) loss upon settlement of cash flow hedges |  |  | (10.0 | ) |  |  | 1.5 |  |  |  | (18.0 | ) |  |  | 1.6 |
Reclassification due to forecasted transactions probable of not occurring |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.2 |
Less: income tax benefit (expense)2 |  |  | 2.4 |  |  |  | (0.3 | ) |  |  | 4.2 |  |  |  | (0.4 | )
Net (gain) loss reclassified from AOCI to Net income |  |  | (7.6 | ) |  |  | 1.2 |  |  |  | (13.8 | ) |  |  | 1.4 |
Other comprehensive (loss) income, net of tax |  |  | (0.7 | ) |  |  | 1.6 |  |  |  | 5.5 |  |  |  | 3.3 |
Ending balance 3 |  | $ | 6.9 |  |  | $ | 5.4 |  |  | $ | 6.9 |  |  | $ | 5.4 |
Total AOCI ending balance |  | $ | 26.7 |  |  | $ | 16.3 |  |  | $ | 26.7 |  |  | $ | 16.3 |

1.
Amounts amortized out of AOCI related to pension and other postretirement and postemployment benefits were included within Net periodic postretirement and postemployment benefit cost (see Note 3).
2.
Income tax amounts reclassified out of AOCI were included as a component of Income tax provision.
3.
As of September 30, 2025, we estimate a net mark-to-market gain before tax of $8.7 million in AOCI will be reclassified into Net income upon settlement within the next 12 months.

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KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

9. Other Income, Net

The following table presents the components of Other income, net (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Interest income |  | $ | 0.2 |  |  | $ | 0.9 |  |  | $ | 0.6 |  |  | $ | 3.0 |
Net periodic postretirement and postemployment benefit cost |  |  | (1.2 | ) |  |  | (1.5 | ) |  |  | (3.8 | ) |  |  | (3.3 | )
Unrealized gain on equity securities |  |  | 0.3 |  |  |  | 0.2 |  |  |  | 0.4 |  |  |  | 0.5 |
Gain on disposition of non-operating property, plant and equipment |  |  | 10.3 |  |  |  | 4.4 |  |  |  | 10.3 |  |  |  | 3.9 |
Gain on business interruption insurance recoveries 1 |  |  | 1.6 |  |  |  | 4.6 |  |  |  | 6.6 |  |  |  | 15.1 |
All other, net |  |  | 0.2 |  |  |  | 0.1 |  |  |  | 0.3 |  |  |  | (0.1 | )
Other income, net |  | $ | 11.4 |  |  | $ | 8.7 |  |  | $ | 14.4 |  |  | $ | 19.1 |

1.
Represents advances against business interruption insurance claims. We recognize such advances in the period in which the insurance proceeds are received or become realizable. During the nine months ended September 30, 2025 and September 30, 2024, we received net cash proceeds of $6.4 million and $13.4 million, respectively.

Supply Chain Financing. We are party to several supply chain financing arrangements, in which we may sell certain of our customers’ trade accounts receivable to such customers’ financial institutions without recourse. During the quarter and nine months ended September 30, 2025, we sold trade accounts receivable totaling $255.9 million and $740.1 million, respectively, related to these supply chain financing arrangements, of which our customers’ financial institutions applied discount fees totaling $6.2 million and $17.2 million, respectively. During the quarter and nine months ended September 30, 2024, we sold trade accounts receivable totaling $260.5 million and $792.9 million, respectively, related to these supply chain financing arrangements, of which our customers’ financial institutions applied discount fees totaling $6.1 million and $18.9 million, respectively. To the extent discount fees related to the sale of trade accounts receivable under supply chain financing arrangements are not reimbursed by our customers, they are included in Other income, net. As of September 30, 2025, we had been and/or expected to be substantially reimbursed by our customers for these discount fees, in accordance with the underlying sales agreements.

10. Income Tax Matters

The following table presents the income tax provision by region (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |  |  | 2025 |  |  | 2024 As Adjusted 1 |
Domestic |  | $ | (8.0 | ) |  | $ | (1.8 | ) |  | $ | (20.6 | ) |  | $ | (12.0 | )
Foreign |  |  | (0.3 | ) |  |  | (0.6 | ) |  |  | (1.6 | ) |  |  | (1.6 | )
Total |  | $ | (8.3 | ) |  | $ | (2.4 | ) |  | $ | (22.2 | ) |  | $ | (13.6 | )

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.

The income tax provision for the quarters ended September 30, 2025 and September 30, 2024 was $8.3 million and $2.4 million, respectively, reflecting an effective tax rate of 17% and 21%, respectively. The difference between the effective tax rate and the projected blended statutory tax rate for the quarter ended September 30, 2025 was primarily due to a decrease of 7% related to Federal research and development credits, partially offset by an increase of 2% related to non-deductible compensation expense. There was no material difference between the effective tax rate and the blended statutory tax rate for the quarter ended September 30, 2024.

The income tax provision for the nine months ended September 30, 2025 and September 30, 2024 was $22.2 million and $13.6 million, respectively, reflecting an effective tax rate of 21% and 23%, respectively. There was no material difference between the effective tax rate and the blended statutory tax rate for the nine months ended September 30, 2025 and September 30, 2024.

20

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KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

Our gross unrecognized benefits relating to uncertain tax positions were $7.7 million and $6.9 million at September 30, 2025 and December 31, 2024, respectively, of which, $7.7 million and $6.9 million would be recorded through our income tax provision and thus, impact the effective tax rate at September 30, 2025 and December 31, 2024, respectively, if the gross unrecognized tax benefits were to be recognized.

On July 4, 2025, President Trump signed into law the One Big Beautiful Bill Act ("OBBBA"). The OBBBA made permanent key elements of the Tax Cuts and Jobs Act, including 100% bonus depreciation, domestic research cost expensing, and the business interest expense limitation. ASC 740, “Income Taxes”, requires the effects of changes in tax rates and laws on deferred tax balances to be recognized in the period in which the legislation is enacted. Consequently, as of the date of enactment, the Company evaluated all deferred tax balances under the newly enacted tax law and made all changes required to the Company's Form 10-Q for the quarter ended September 30, 2025, which included no material impact to the income tax rate.

11. Earnings Per Share

Basic net income per share is computed by dividing distributed and undistributed net income allocable to common shares by the weighted-average number of common shares outstanding during the app licable period. The basic weighted-average number of common shares outstanding during the period excludes non-vested share-based payment awards. Basic and diluted net income per share was calculated under the two-class method for the quarters and nine months ended September 30, 2025 and September 30, 2024.

The following table sets forth the computation of basic and diluted net income per share (in millions of dollars, except share and per share amounts):

|  | Quarter Ended September 30, |  |  | Nine Months Ended June 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |  |  | 2025 |  |  | 2024 As Adjusted 1 |
Numerator: |  |  |  |  |  |  |  |  |  |  |  |
Net income available to common shareholders 2 |  | $ | 39.5 |  |  | $ | 8.8 |  |  | $ | 84.3 |  |  | $ | 45.9 |
Denominator – Weighted-average common shares outstanding (in thousands): |  |  |  |  |  |  |  |  |  |  |  |
Basic |  |  | 16,192 |  |  |  | 16,087 |  |  |  | 16,156 |  |  |  | 16,062 |
Add: dilutive effect of non-vested common shares, restricted stock units and performance shares 3 |  |  | 420 |  |  |  | 248 |  |  |  | 355 |  |  |  | 229 |
Diluted |  |  | 16,612 |  |  |  | 16,335 |  |  |  | 16,511 |  |  |  | 16,291 |
Net income per common share, Basic: |  | $ | 2.44 |  |  | $ | 0.54 |  |  | $ | 5.22 |  |  | $ | 2.85 |
Net income per common share, Diluted: |  | $ | 2.38 |  |  | $ | 0.54 |  |  | $ | 5.10 |  |  | $ | 2.81 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
2.
Represents Net income less distributed and undistributed earnings allocated to non-vested restricted stock awards that contain non-forfeitable rights to dividends.
3.
Quantities in the following discussion are denoted in whole shares. During the quarter and nine months ended September 30, 2025 approximately 1 and 196 shares, respectively, were excluded from the weighted-average diluted shares computation as their inclusion would have been anti‑dilutive. For the quarter and nine months ended September 30, 2024, approximately 120 and 700 shares, respectively, were excluded from the weighted-average diluted shares computation as their inclusion would have been anti‑dilutive.

21

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KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

12. Supplemental Cash Flow Information

|  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |
|  | (In millions of dollars) |
Interest paid |  | $ | 33.3 |  |  | $ | 30.5 |
Non-cash investing and financing activities (included in Accounts payable): |  |  |  |  |  |
Unpaid purchases of property and equipment |  | $ | 23.5 |  |  | $ | 24.7 |
Supplemental lease disclosures: |  |  |  |  |  |
Operating lease liabilities arising from obtaining operating lease assets |  | $ | 1.9 |  |  | $ | 0.9 |
Cash paid for amounts included in the measurement of operating lease liabilities |  | $ | 5.2 |  |  | $ | 6.1 |
Finance lease liabilities arising from obtaining finance lease assets |  | $ | 1.7 |  |  | $ | 2.6 |

|  | As of September 30, |
|  | 2025 |  |  | 2024 |
|  | (In millions of dollars) |
Components of cash, cash equivalents and restricted cash: |  |  |  |  |  |
Cash and cash equivalents |  | $ | 17.2 |  |  | $ | 45.7 |
Restricted cash included in Other assets 1 |  |  | 19.8 |  |  |  | 18.3 |
Total cash, cash equivalents and restricted cash presented on our Statements of Consolidated Cash Flows |  | $ | 37.0 |  |  | $ | 64.0 |

1.
We are required to keep on deposit certain amounts that are pledged or held as collateral relating to workers’ compensation and other agreements. We account for such deposits as restricted cash. From time to time, such restricted funds could be returned to us or we could be required to pledge additional cash.

13. Business, Product, and Geographical Area Information

Our primary line of business is the production of semi-fabricated specialty aluminum mill products, such as plate and sheet, bare and coated coils, and extruded and drawn products, primarily used in our Aero/HS Products, Packaging, GE Products, and Automotive Extrusions end markets. We operate production facilities in the United States and Canada. We have one operating and reportable segment. Our determination that we operate as a single segment is consistent with the financial information regularly viewed by the chief operating decision maker (“CODM”) to evaluate performance and make decisions regarding resource allocation. The CODM uses Net income to measure segment profitability in deciding whether to reinvest profits into the segment or into other parts of the entity, such as for acquisitions or to pay dividends.

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KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

The following table presents the significant segment expenses that are provided to the CODM (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |  |  | 2025 |  |  | 2024 As Adjusted 1 |
Net sales |  | $ | 843.5 |  |  | $ | 747.7 |  |  | $ | 2,444.0 |  |  | $ | 2,258.6 |
Less: |  |  |  |  |  |  |  |  |  |  |  |
Cost of products sold, excluding depreciation and amortization |  |  |  |  |  |  |  |  |  |  |  |
Hedged cost of alloyed metal 2 |  |  | 492.8 |  |  |  | 385.7 |  |  |  | 1,355.9 |  |  |  | 1,160.8 |
Manufacturing costs 3 |  |  | 158.8 |  |  |  | 208.2 |  |  |  | 532.5 |  |  |  | 599.1 |
Plant overhead 4 |  |  | 45.9 |  |  |  | 45.0 |  |  |  | 136.0 |  |  |  | 133.5 |
Freight costs |  |  | 21.6 |  |  |  | 23.4 |  |  |  | 63.6 |  |  |  | 69.1 |
Other cost of products sold 5 |  |  | 9.7 |  |  |  | 13.7 |  |  |  | 37.0 |  |  |  | 34.6 |
Depreciation and amortization |  |  | 32.0 |  |  |  | 29.0 |  |  |  | 91.6 |  |  |  | 86.8 |
Selling, general, administrative, research and development |  |  |  |  |  |  |  |  |  |  |  |
Research and development costs |  |  | 0.4 |  |  |  | 0.5 |  |  |  | 1.0 |  |  |  | 1.7 |
Employee costs 6 |  |  | 24.7 |  |  |  | 20.2 |  |  |  | 69.9 |  |  |  | 63.8 |
Other selling, general and administrative costs 7 |  |  | 8.8 |  |  |  | 8.1 |  |  |  | 26.4 |  |  |  | 27.5 |
Restructuring costs |  |  | — |  |  |  | 0.7 |  |  |  | 1.9 |  |  |  | 7.6 |
Other operating charges, net |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.4 |
Interest expense |  |  | 12.4 |  |  |  | 10.7 |  |  |  | 36.1 |  |  |  | 33.3 |
Other income, net – Note 9 |  |  | (11.4 | ) |  |  | (8.7 | ) |  |  | (14.4 | ) |  |  | (19.1 | )
Income tax provision |  |  | 8.3 |  |  |  | 2.4 |  |  |  | 22.2 |  |  |  | 13.6 |
Net income |  | $ | 39.5 |  |  | $ | 8.8 |  |  | $ | 84.3 |  |  | $ | 45.9 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
2.
Hedged cost of alloyed metal includes cost of aluminum at the MWTP and the cost of alloying elements used in the production process. For the quarters ended September 30, 2025 and September 30, 2024, this metric also includes metal price exposure on shipments that we hedg ed with realized gains (losses) upon settlement of $10.2 million and ($2.1) million, respectively. For the nine months ended September 30, 2025 and September 30, 2024, this metric also includes metal price exposure on shipments that we hedged with realized gains (losses) upon settlement of $15.4 million and ($2.2) million, respectively.
3.
Manufacturing costs primarily includes labor, utilities, supplies, metal valuation impacts, metal profits, and other materials, excluding alloys incurred at our various production facilities.
4.
Plant overhead includes salaried employee costs, property taxes, and insurance associated with our various production facilities.
5.
Other cost of products sold primarily includes lease expense, accretion expense related to conditional asset retirement obligations, gains and losses on operating asset disposals, and major maintenance costs.
6.
Employee costs include non direct labor salaries, benefits, and incentive compensation.
7.
Other selling, general and administrative costs primarily include professional services, computer hardware and software costs, office rent, and utilities.

The CODM does not review asset and capital expenditure information by reportable operating segment as such information is presented to the CODM on a consolidated basis.

23

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KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

The following table presents Net sales by end market applications and by timing of control transfer (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Net sales: |  |  |  |  |  |  |  |  |  |  |  |
Aero/HS Products |  | $ | 182.2 |  |  | $ | 213.1 |  |  | $ | 624.8 |  |  | $ | 659.7 |
Packaging |  |  | 393.9 |  |  |  | 319.5 |  |  |  | 1,049.0 |  |  |  | 930.0 |
GE Products |  |  | 192.2 |  |  |  | 150.7 |  |  |  | 559.2 |  |  |  | 466.3 |
Automotive Extrusions |  |  | 75.2 |  |  |  | 62.1 |  |  |  | 211.0 |  |  |  | 195.3 |
Other products |  |  | — |  |  |  | 2.3 |  |  |  | — |  |  |  | 7.3 |
Total net sales |  | $ | 843.5 |  |  | $ | 747.7 |  |  | $ | 2,444.0 |  |  | $ | 2,258.6 |
Timing of revenue recognition: |  |  |  |  |  |  |  |  |  |  |  |
Products transferred at a point in time |  | $ | 670.7 |  |  | $ | 580.2 |  |  | $ | 1,888.1 |  |  | $ | 1,741.4 |
Products transferred over time |  |  | 172.8 |  |  |  | 167.5 |  |  |  | 555.9 |  |  |  | 517.2 |
Total net sales |  | $ | 843.5 |  |  | $ | 747.7 |  |  | $ | 2,444.0 |  |  | $ | 2,258.6 |

The following table presents geographic information for income taxes paid (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Income taxes paid: |  |  |  |  |  |  |  |  |  |  |  |
Domestic |  | $ | — |  |  | $ | 0.2 |  |  | $ | 2.6 |  |  | $ | 0.4 |
Foreign |  |  | 0.9 |  |  |  | 0.3 |  |  |  | 3.6 |  |  |  | 2.5 |
Total income taxes paid |  | $ | 0.9 |  |  | $ | 0.5 |  |  | $ | 6.2 |  |  | $ | 2.9 |

14. Change in Accounting Principle

Effective January 1, 2025, we changed our inventory valuation methodology for finished products, work-in-process, and raw material inventories from LIFO to WAC. All prior periods presented have been adjusted to apply the new method retrospectively.

Certain financial statement line items in our Statements of Consolidated Income for the quarter and nine months ended September 30, 2024, our Statements of Consolidated Cash Flows for the nine months ended September 30, 2024, and our Consolidated Balance Sheets and Consolidated Stockholders’ Equity as of September 30, 2024 and December 31, 2024, were adjusted as follows (in millions of dollars, except per share amounts):

24

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KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

|  | As Previously Reported |  | Effect of WAC Change |  | As Adjusted |
Statements of Consolidated Income (Loss) for the quarter ended September 30, 2024 |  |  |  |  |  |  |
Cost of products sold, excluding depreciation and amortization |  | $ | 671.8 |  | $ | 4.2 |  | $ | 676.0 |
Operating income |  |  | 17.4 |  |  | (4.2 | ) |  | 13.2 |
Income tax provision |  |  | (3.4 | ) |  | 1.0 |  |  | (2.4 | )
Net income |  |  | 12.0 |  |  | (3.2 | ) |  | 8.8 |
Net income per common share: |  |  |  |  |  |  |
Basic |  | $ | 0.75 |  | $ | (0.21 | ) | $ | 0.54 |
Diluted |  | $ | 0.74 |  | $ | (0.20 | ) | $ | 0.54 |
Statements of Consolidated Income (Loss) for the nine months ended September 30, 2024 |  |  |  |  |  |  |
Cost of products sold, excluding depreciation and amortization |  | $ | 2,005.2 |  | $ | (8.1 | ) | $ | 1,997.1 |
Operating income |  |  | 65.6 |  |  | 8.1 |  |  | 73.7 |
Income tax provision |  |  | (11.7 | ) |  | (1.9 | ) |  | (13.6 | )
Net income |  |  | 39.7 |  |  | 6.2 |  |  | 45.9 |
Net income per common share: |  |  |  |  |  |  |
Basic |  | $ | 2.47 |  | $ | 0.38 |  | $ | 2.85 |
Diluted |  | $ | 2.44 |  | $ | 0.37 |  | $ | 2.81 |
Statements of Consolidated Cash Flows for the nine months ended September 30, 2024 |  |  |  |  |  |  |
Net income |  | $ | 39.7 |  | $ | 6.2 |  | $ | 45.9 |
Deferred income taxes |  |  | 8.5 |  |  | 1.9 |  |  | 10.4 |
LIFO valuation inventory expense |  |  | 8.8 |  |  | (8.8 | ) |  | — |
Inventories |  |  | (8.7 | ) |  | 0.7 |  |  | (8.0 | )
Net cash provided by operating activities |  |  | 123.7 |  |  | — |  |  | 123.7 |
Consolidated Balance Sheet as of September 30, 2024 |  |  |  |  |  |  |
Receivables, other |  | $ | 0.9 |  | $ | 0.1 |  | $ | 1.0 |
Inventories |  |  | 473.9 |  |  | 81.6 |  |  | 555.5 |
Deferred tax assets, net |  |  | 6.3 |  |  | (2.7 | ) |  | 3.6 |
Deferred tax liabilities |  |  | 23.7 |  |  | 16.6 |  |  | 40.3 |
Retained earnings |  |  | 11.8 |  |  | 62.4 |  |  | 74.2 |
Consolidated Balance Sheet as of December 31, 2024 |  |  |  |  |  |  |
Receivables, other |  | $ | 22.0 |  | $ | 0.2 |  | $ | 22.2 |
Inventories |  |  | 503.9 |  |  | 98.0 |  |  | 601.9 |
Deferred tax assets, net |  |  | 7.2 |  |  | (3.2 | ) |  | 4.0 |
Other accrued liabilities |  |  | 79.4 |  |  | (0.1 | ) |  | 79.3 |
Deferred tax liabilities |  |  | 24.1 |  |  | 20.0 |  |  | 44.1 |
Retained earnings |  |  | 6.2 |  |  | 75.1 |  |  | 81.3 |

25

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KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

The following table compares the amounts that would have been reported under LIFO with amounts reported under WAC in the current period Interim Consolidated Financial Statements (in millions of dollars, except per share amounts):

|  | As Computed (using LIFO) |  | Effect of Change |  | As Reported (using WAC) |
Statements of Consolidated Income (Loss) for the quarter ended September 30, 2025 |  |  |  |  |  |  |
Cost of products sold, excluding depreciation and amortization |  | $ | 790.2 |  | $ | (61.4 | ) | $ | 728.8 |
Operating (loss) income |  |  | (12.6 | ) |  | 61.4 |  |  | 48.8 |
Income tax benefit (provision) |  |  | 1.4 |  |  | (9.7 | ) |  | (8.3 | )
Net (loss) income |  |  | (12.2 | ) |  | 51.7 |  |  | 39.5 |
Net (loss) income per common share: |  |  |  |  |  |  |
Basic |  | $ | (0.75 | ) | $ | 3.19 |  | $ | 2.44 |
Diluted |  | $ | (0.75 | ) | $ | 3.13 |  | $ | 2.38 |
Statements of Consolidated Income (Loss) for the nine months ended September 30, 2025 |  |  |  |  |  |  |
Cost of products sold, excluding depreciation and amortization |  | $ | 2,242.3 |  | $ | (117.3 | ) | $ | 2,125.0 |
Operating income |  |  | 10.9 |  |  | 117.3 |  |  | 128.2 |
Income tax provision |  |  | (0.1 | ) |  | (22.1 | ) |  | (22.2 | )
Net (loss) income |  |  | (10.9 | ) |  | 95.2 |  |  | 84.3 |
Net (loss) income per common share: |  |  |  |  |  |  |
Basic |  | $ | (0.68 | ) | $ | 5.90 |  | $ | 5.22 |
Diluted |  | $ | (0.68 | ) | $ | 5.78 |  | $ | 5.10 |
Statements of Consolidated Cash Flows for the nine months ended September 30, 2025 |  |  |  |  |  |  |
Net (loss) income |  | $ | (10.9 | ) | $ | 95.2 |  | $ | 84.3 |
Deferred income taxes |  |  | (0.9 | ) |  | 22.1 |  |  | 21.2 |
Inventories |  |  | 16.9 |  |  | (117.3 | ) |  | (100.4 | )
Net cash provided by operating activities |  |  | 132.0 |  |  | — |  |  | 132.0 |
Consolidated Balance Sheet as of September 30, 2025 |  |  |  |  |  |  |
Receivables, other |  | $ | 32.1 |  | $ | 0.2 |  | $ | 32.3 |
Inventories |  |  | 487.0 |  |  | 215.3 |  |  | 702.3 |
Deferred tax assets, net |  |  | 7.1 |  |  | (5.7 | ) |  | 1.4 |
Other accrued liabilities |  |  | 49.6 |  |  | (0.1 | ) |  | 49.5 |
Deferred tax liabilities |  |  | 25.0 |  |  | 39.6 |  |  | 64.6 |
Retained (deficit) earnings |  |  | (43.2 | ) |  | 170.3 |  |  | 127.1 |

15. Subsequent Events

Dividend Declaration. On October 14, 2025, we announced that our Board of Directors declared a quarterly cash dividend of $0.77 per common share. As such, we expect to pay approximately $12.8 million (including dividend equivalents) on or about November 14, 2025 to stockholders of record and the holders of certain restricted stock units at the close of business on October 24, 2025.

Revolving Credit Facility. On October 14, 2025, we entered into amendment No. 5 to our Revolving Credit Facility with a syndicate of commercial lenders led by Wells Fargo Bank, National Association (the “Amended Credit Facility”). The Amended Credit Facility, among other things, (i) contains a maximum commitment amount of $575.0 million (of which up to a maximum of $50.0 million may be utilized for letters of credit), (ii) allows the Company to request an increase of the revolving commitments by up to an amount equal to $200.0 million plus an additional amount for a first-in last-out tranche, subject to certain conditions and the agreement

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Notes Index

KAISER ALUMINUM CORPORATION AND SUBSIDIARY COMPANIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS – UNAUDITED

of one or more lenders to provide such increased commitment, and (iii) is set to mature on the earlier of (i) March 1, 2028, if by that date the scheduled maturity of the Company’s senior notes due 2028 has not been extended to a date not earlier than 90 days after October 14, 2030, repaid in full, or refinanced or replaced on terms mutually satisfactory to the Borrowers and Wells Fargo; and (ii) October 14, 2030. The amount we can borrow under the Amended Credit Facility is determined by the value of our eligible accounts receivable and inventory and certain other assets, which serve as collateral for the Amended Credit Facility. Our effective interest rate on outstanding borrowings under the Amended Credit Facility bear interest at a rate equal to either a base rate or the secured overnight financing rate (SOFR), plus, in each case, a specified variable percentage of between 125 basis points and 150 basis points for SOFR loans (or 25 basis points and 50 basis points for base rate loans) determined by reference to the then-remaining borrowing availability under the Amended Credit Facility and, in certain instances, a fixed margin. At the time of execution of the Amended Credit Facility, we had no outstanding borrowings under the previous revolving credit facility nor did we borrow on the Amended Credit Facility. As of the effective date, under the Amended Credit Facility, there were outstanding letters of credit totaling $14.6 million.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Forward-Looking Statements

This Quarterly Report on Form 10-Q contains statements which constitute “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. These statements appear throughout this Report and can be identified by the use of forward-looking terminology such as “believes,” “expects,” “may,” “estimates,” “will,” “should,” “plans” or “anticipates,” or the negative of the foregoing or other variations of comparable terminology, or by discussions of strategy. Readers are cautioned that any such forward‑looking statements are not guarantees of future performance and involve significant risks and uncertainties and that actual results may vary from those in the forward-looking statements as a result of various factors. These factors include: (i) the effectiveness of management’s strategies and decisions, including strategic investments, capital spending strategies, cost reduction initiatives, sourcing strategies, processes and countermeasures implemented to address operational and supply chain challenges and the execution of those strategies; (ii) the execution and timing of strategic investments; (iii) general economic and business conditions, including the impact of geopolitical factors and governmental and other actions taken in response, cyclicality, reshoring, labor challenges, supply interruptions, customer disruptions, customer inventory imbalances and supply chain issues, and other conditions that impact demand drivers in the Aero/HS Products, Packaging, GE Products, and Automotive Extrusions end markets we serve; (iv) our ability to participate in mature and anticipated new automotive programs expected to launch in the future and successfully launch new automotive programs; (v) changes or shifts in defense spending due to competing national priorities; (vi) pricing, market conditions and our ability to effectively execute commercial and labor strategies, pass through cost increases, including the institution of surcharges, and flex costs in response to inflation, volatile commodity costs and changing economic conditions; (vii) developments in technology; (viii) the impact of our future earnings, cash flows, financial condition, capital requirements and other factors on our financial strength and flexibility; (ix) new or modified statutory or regulatory requirements; (x) the successful integration of acquired operations and technologies and (xi) stakeholders’, including regulators’ and customers’, views regarding our sustainability goals and initiatives and the impact of factors outside of our control on such goals and initiatives. This Item and Part I, Item 1A. “Risk Factors” included in our Annual Report on Form 10-K for the year ended December 31, 2024, each identify other factors that could cause actual results to vary. No assurance can be given that these are all of the factors that could cause actual results to vary materially from the forward looking statements.

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with Part I, Item 1. “Financial Statements” of this Report and our consolidated financial statements and related notes included in Part II, Item 8. “Financial Statements and Supplementary Data” of our Annual Report on Form 10-K for the year ended December 31, 2024.

Basis of Presentation

Effective January 1, 2025, we changed our inventory valuation methodology from LIFO to WAC. The impact of this change in accounting principle to both the current period and, as applied retrospectively, to the comparable period of the prior fiscal year is disclosed in Note 14 of the Form 10-Q. Prior period information provided in this Management’s Discussion and Analysis has been updated to reflect the retrospective application of the change in accounting principle.

Non-GAAP Financial Measures

This information contains certain non-GAAP financial measures. A non-GAAP financial measure is defined as a numerical measure of a company’s financial performance that excludes or includes amounts so as to be different than the most directly comparable measure calculated and presented in accordance with GAAP in the statements of income, balance sheets or statements of cash flows of the company. We have provided a reconciliation of non‑GAAP financial measures to the most directly comparable financial measure in the accompanying tables. We have also provided discussion of the reasons we believe that presentation of the non-GAAP financial measures provides useful information to investors, as well as any additional ways in which we use the non-GAAP financial measures. The non-GAAP financial measures used in the following discussions are Conversion Revenue (defined as Net sales less the Hedged Cost of Alloyed Metal, see below in “Metal Pricing Policies” discussion), Adjusted EBITDA and ratios related thereto. These measures are presented because management uses this information to monitor and evaluate financial results and trends and believes this information to also be useful for investors.

In the discussion of operating results below, we refer to certain items as “non-run-rate items.” For purposes of such discussion, non-run-rate items are items that, while they may recur from period-to-period: (i) are particularly material to results; (ii) affect costs primarily as a result of external market factors; and (iii) may not recur in future periods if the same level of underlying performance were to occur. Non-run-rate items are part of our business and operating environment but are worthy of being highlighted for the benefit of readers of our financial statements. Our intent is to allow users of the financial statements to consider our results both in light of and separately from such items. For a reconciliation of Adjusted EBITDA to Net income, see below in “Results of Operations - Selected Operational and Financial Information.” Reconciliations of certain forward‑looking non-GAAP financial measures to comparable

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GAAP measures are not provided because certain items required for such reconciliations are outside of our control and/or cannot be reasonably predicted or provided without unreasonable effort.

Metal Pricing Policies

A fundamental part of our business model is to remain neutral to the impact from fluctuations in the market price for aluminum and certain alloys, thereby earning profit predominantly from the conversion of aluminum into semi-fabricated mill products. We refer to this as “metal price neutrality.” We purchase primary, rolling ingot and scrap, or recycled, aluminum, our main raw material, and alloys at prices that fluctuate on a monthly basis, and our pricing policies generally allow us to pass the current month underlying index cost of aluminum and certain alloys through to our customers so that we remain neutral to metal pricing. We may also enter into firm-price customer sales agreements that specify a firm underlying metal price plus a conversion price. Firm-price sales agreements create price exposure for us, which we mitigate through hedging and related programs with an objective to remain metal price neutral. Additionally, we have certain contracts that may adjust certain alloy prices for a forward period based on an average prior period cost for such alloys. As a result, until the selling price resets, we can experience an adverse impact when alloy prices increase and a favorable impact when alloy prices decrease.

In order to allow users of our financial statements to consider the impact of aluminum and alloy cost on our Net sales, we disclose Net sales as well as Conversion Revenue, which is Net sales less the Hedged Cost of Alloyed Metal. As used in this discussion, “Hedged Cost of Alloyed Metal” is the cost of aluminum at the average MWTP plus the cost of alloying elements and any realized gains and/or losses on settled hedges related to the metal sold in the referenced period. The average MWTP of aluminum reflects the primary aluminum supply/demand dynamics in North America. For a reconciliation of Conversion Revenue to Net sales, see below in “Results of Operations - Selected Operational and Financial Information.”

Business Overview

We manufacture and sell semi-fabricated specialty aluminum mill products for the following end market applications: (i) Aero/HS Products; (ii) Packaging; (iii) GE Products; and (iv) Automotive Extrusions. Our fabricated aluminum mill products include flat-rolled (plate, sheet and coil), extruded (rod, bar, hollows and shapes), drawn (rod, bar, pipe, tube and wire) and certain cast aluminum products. The sophistication of our products is due to the metallurgy and physical properties of the metal and the special characteristics that are required for particular end uses. We strategically choose to serve technically challenging applications for which we can deploy our core metallurgical and process technology capabilities to produce highly engineered mill products with differentiated characteristics that present opportunities for us to receive premium pricing and to create long-term profitable growth.

With respect to the global market for flat-rolled aluminum mill products, our focus is on heat treat plate and sheet for applications that require higher strength and other desired product attributes that cannot be achieved by common alloy rolled products. The primary end market applications of flat-rolled heat treat plate and sheet, which are produced at Trentwood, are Aero/HS Products (which we sell globally) and GE Products (which we predominantly sell within North America). The primary end market application of bare and coated aluminum coil, which are produced at Warrick, is Packaging (which we sell in North America). Our Packaging products require demanding attributes and can be further processed to include coating and slitting depending on customer specifications.

In the areas of aluminum extrusions, we focus on demanding Aero/HS Products, GE Products, and Automotive Extrusions that require high strength, machinability or other specific properties where we can create and maintain a defensible competitive position because of our technical expertise, strong production capability and high product quality. Our 10 active extrusion/drawing facilities, nine of which are in the United States and one of which is in Canada, serve primarily North American demand for aerospace, general engineering, or automotive applications. Additionally, we have a facility in Columbia, New Jersey, that focuses on multi-material advanced manufacturing methods and techniques, which include multi-axis computer numerical control machining, additive manufacturing (“3D Printing”), welding and fabrication for demanding aerospace and defense, high technology, general industrial, and automotive applications. Our consolidated Net sales for the nine months ended September 30, 2025 totaled $2,444.0 million on approximately 834.2 million pounds shipped from our facilities. We employed approximately 3,900 people at September 30, 2025.

We have long-standing relationships with our customers, which consist primarily of blue-chip companies including leading aerospace and automotive manufacturers, tier one aerospace and automotive suppliers, food and beverage packaging manufacturers, and metal service centers. Approximately 70% of our shipments is sold direct to manufacturers or tier one suppliers and approximately 30% is sold to metal service centers. In our served markets, we seek to be the supplier of choice by pursuing “Best in Class” customer satisfaction driven by quality, availability, service and delivery performance. We believe we differentiate our product portfolio through our broad product offering and our Kaiser Select® products, which are engineered and manufactured to deliver enhanced product characteristics with improved consistency, so as to result in better performance, lower waste and, in many cases, lower production cost for our customers.

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As part of the manufacturing process, we purchase primary, rolling ingot and scrap, or recycled, aluminum, our main raw material, and alloys at prices that fluctuate on a daily basis. We typically purchase scrap at a discount to the MWTP which can vary depending on market dynamics and availability. As a result, we can experience an adverse impact when scrap discounts decrease and a favorable impact when scrap discounts increase. Additionally, as our manufacturing process takes approximately one to four months to complete, depending on the complexity and additional fabrication processes required, and we value our inventory on a weighted average cost methodology, the weighted average cost of our inventory may lag the current metal selling cost. As such, our results may reflect a favorable impact when metal prices increase and adverse impact when metal prices decrease. We refer to this as Metal Price Lag, which can be influenced not only by the amount of change in price but also the volatility and timing of the change of metal prices during the reporting period.

Highlights for the quarter ended September 30, 2025:

•
Net sales $843.5 million; Conversion Revenue $350.7 million;
•
Net income $39.5 million; Net income per diluted share $2.38; and
•
Cash dividends and dividend equivalents of $0.77 per share or $12.8 million paid during the quarter ended September 30, 2025.

Results of Operations

Consolidated Results of Operations

Net Sales. The following table sets forth, for the quarters ended September 30, 2025 and September 30, 2024, shipments (in millions of pounds) and Net sales (in millions of dollars) by end market applications and the respective fluctuations.

|  | Quarter Ended September 30, |  |  |  |  |  |  |  |  |
|  | 2025 |  | 2024 |  |  |  |  |
|  | Shipments |  | Net sales |  | Shipments |  | Net sales |  | Shipment Change |  | % Increase (Decrease) |  | Net sales Change |  | % Increase (Decrease) |
Aero/HS Products |  | 41.8 |  | $ | 182.2 |  |  | 59.5 |  | $ | 213.1 |  |  | (17.7 | ) |  | (30 | %) | $ | (30.9 | ) |  | (15 | %)
Packaging |  | 144.1 |  |  | 393.9 |  |  | 150.9 |  |  | 319.5 |  |  | (6.8 | ) |  | (5 | %) |  | 74.4 |  |  | 23 | %
GE Products |  | 60.4 |  |  | 192.2 |  |  | 55.6 |  |  | 150.7 |  |  | 4.8 |  |  | 9 | % |  | 41.5 |  |  | 28 | %
Automotive Extrusions |  | 23.9 |  |  | 75.2 |  |  | 25.2 |  |  | 62.1 |  |  | (1.3 | ) |  | (5 | %) |  | 13.1 |  |  | 21 | %
Other Products |  |  | — |  |  | — |  |  | 1.0 |  |  | 2.3 |  |  | (1.0 | ) |  | (100 | %) |  | (2.3 | ) |  | (100 | %)
Total |  |  | 270.2 |  | $ | 843.5 |  |  | 292.2 |  | $ | 747.7 |  |  | (22.0 | ) |  | (8 | %) | $ | 95.8 |  |  | 13 | %

The increase in Net sales reflected an increase in the average realized sales price per pound of $0.56 (22%). This benefit was partially offset by a 22.0 million pound (8%) decrease in shipment volume, primarily driven by a planned partial outage at Trentwood in conjunction with the Phase VII capacity expansion project.

The following table sets forth, for the nine months ended September 30, 2025 and September 30, 2024, shipments (in millions of pounds) and Net sales (in millions of dollars) by end market applications and the respective fluctuations.

|  | Nine Months Ended September 30, |  |  |  |  |  |  |  |  |
|  | 2025 |  | 2024 |  |  |  |  |
|  | Shipments |  | Net sales |  | Shipments |  | Net sales |  | Shipment Change |  | % Increase (Decrease) |  | Net sales Change |  | % Increase (Decrease) |
Aero/HS Products |  | 158.0 |  | $ | 624.8 |  |  | 184.6 |  | $ | 659.7 |  |  | (26.6 | ) |  | (14 | %) | $ | (34.9 | ) |  | (5 | %)
Packaging |  | 415.4 |  |  | 1,049.0 |  |  | 439.2 |  |  | 930.0 |  |  | (23.8 | ) |  | (5 | %) |  | 119.0 |  |  | 13 | %
GE Products |  | 188.9 |  |  | 559.2 |  |  | 173.2 |  |  | 466.3 |  |  | 15.7 |  |  | 9 | % |  | 92.9 |  |  | 20 | %
Automotive Extrusions |  | 71.9 |  |  | 211.0 |  |  | 79.8 |  |  | 195.3 |  |  | (7.9 | ) |  | (10 | %) |  | 15.7 |  |  | 8 | %
Other Products |  |  | — |  |  | — |  |  | 3.2 |  |  | 7.3 |  |  | (3.2 | ) |  | (100 | %) |  | (7.3 | ) |  | (100 | %)
Total |  |  | 834.2 |  | $ | 2,444.0 |  |  | 880.0 |  | $ | 2,258.6 |  |  | (45.8 | ) |  | (5 | %) | $ | 185.4 |  |  | 8 | %

The increase in Net sales reflected an increase in the average realized sales price per pound of $0.36 (14%). This benefit was partially offset by a 45.8 million pound (5%) decrease in shipment volume, reflecting the impact of a planned partial outage at Trentwood in conjunction with the Phase VII capacity expansion project.

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COGS. COGS for the quarter ended September 30, 2025 totaled $728.8 million, or 86% of Net sales, compared to $676.0 million, or 90% of Net sales, for the quarter ended September 30, 2024. The total increase reflected the following (in millions of dollars):

|  | Quarter Ended September 30, |  |  |  |  |
|  | 2025 |  | 2024 As Adjusted 1 |  | Change |  | % Increase (Decrease) |
Hedged Cost of Alloyed Metal |  | $ | 492.8 |  | $ | 385.7 |  | $ | 107.1 |  |  | 28 | %
Manufacturing costs |  |  | 158.8 |  |  | 208.2 |  |  | (49.4 | ) |  | (24 | %)
Plant overhead |  |  | 45.9 |  |  | 45.0 |  |  | 0.9 |  |  | 2 | %
Freight costs |  |  | 21.6 |  |  | 23.4 |  |  | (1.8 | ) |  | (8 | %)
Other cost of products sold |  |  | 9.7 |  |  | 13.7 |  |  | (4.0 | ) |  | (29 | %)
Total |  | $ | 728.8 |  | $ | 676.0 |  | $ | 52.8 |  |  | 8 | %

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 of Notes to Interim Consolidated Financial Statements included in this Report for further discussion.

Of the $107.1 million increase in Hedged Cost of Alloyed Metal, $136.1 million was due to an increase in hedged metal prices (see above in our “Net Sales” discussion for further details), partially offset by a $29.0 million decrease attributed to lower shipment volume. The $49.4 million decrease in manufacturing costs was primarily due to favorable metal consumption and lower shipment volume, partially offset by higher costs associated with a planned partial outage at Trentwood for the Phase VII capacity expansion project and the start-up of the fourth coating line at Warrick. The $4.0 million decrease in other cost of products sold was primarily driven by a decrease in legacy environmental costs and a decrease in major maintenance costs. The $1.8 million decrease in freight costs was primarily due to lower shipment volume. For a further discussion of the comparative results of operations for the quarters ended September 30, 2025 and September 30, 2024, see below in “Selected Operational and Financial Information.”

COGS for the nine months ended September 30, 2025 totaled $2,125.0 million, or 87% of Net sales, compared to $1,997.1 million, or 88% of Net sales, for the nine months ended September 30, 2024. The total increase reflected the following (in millions of dollars):

|  | Nine Months Ended September 30, |  |  |  |  |
|  | 2025 |  | 2024 As Adjusted 1 |  | Change |  | % Increase (Decrease) |
Hedged Cost of Alloyed Metal |  | $ | 1,355.9 |  | $ | 1,160.8 |  | $ | 195.1 |  |  | 17 | %
Manufacturing costs |  |  | 532.5 |  |  | 599.1 |  |  | (66.6 | ) |  | (11 | %)
Plant overhead |  |  | 136.0 |  |  | 133.5 |  |  | 2.5 |  |  | 2 | %
Freight costs |  |  | 63.6 |  |  | 69.1 |  |  | (5.5 | ) |  | (8 | %)
Other cost of products sold |  |  | 37.0 |  |  | 34.6 |  |  | 2.4 |  |  | 7 | %
Total |  | $ | 2,125.0 |  | $ | 1,997.1 |  | $ | 127.9 |  |  | 6 | %

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 of Notes to Interim Consolidated Financial Statements included in this Report for further discussion.

Of the $195.1 million increase in Hedged Cost of Alloyed Metal, $255.4 million was due to an increase in hedged metal prices (see above in our “Net Sales” discussion for further details), partially offset by a $60.3 million decrease attributed to lower shipment volume. The $66.6 million decrease in manufacturing costs was primarily due to favorable metal consumption and lower shipment volume, partially offset by higher costs associated with a planned partial outage at Trentwood for the Phase VII capacity expansion project and the commissioning and start-up of the fourth coating line at Warrick. The $5.5 million decrease in freight costs was primarily due to lower shipment volume. The $2.4 million increase in other cost of products sold was primarily driven by an increase in major maintenance costs, partially offset by a decrease in legacy environmental costs. For a further discussion of the comparative results of operations for the nine months ended September 30, 2025 and September 30, 2024, see below in “Selected Operational and Financial Information.”

Selling, General, Administrative, Research and Development (“SG&A and R&D”). SG&A and R&D expense totaled $33.9 million and $28.8 million for the quarters ended September 30, 2025 and September 30, 2024, respectively. The increase reflected the following (in millions of dollars):

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|  | Quarter Ended September 30, |  |  |  |  |
|  | 2025 |  | 2024 |  | Change |  | % Increase (Decrease) |
Research and development costs |  | $ | 0.4 |  | $ | 0.5 |  | $ | (0.1 | ) |  | (20 | %)
Employee costs |  |  | 24.7 |  |  | 20.2 |  |  | 4.5 |  |  | 22 | %
Other selling, general and administrative costs |  |  | 8.8 |  |  | 8.1 |  |  | 0.7 |  |  | 9 | %
Total |  | $ | 33.9 |  | $ | 28.8 |  | $ | 5.1 |  |  | 18 | %

SG&A and R&D expense totaled $97.3 million and $93.0 million for the nine months ended September 30, 2025 and September 30, 2024, respectively. The increase reflected the following (in millions of dollars):

|  | Nine Months Ended September 30, |  |  |  |  |
|  | 2025 |  | 2024 |  | Change |  | % Increase (Decrease) |
Research and development costs |  | $ | 1.0 |  | $ | 1.7 |  | $ | (0.7 | ) |  | (41 | %)
Employee costs |  |  | 69.9 |  |  | 63.8 |  |  | 6.1 |  |  | 10 | %
Other selling, general and administrative costs |  |  | 26.4 |  |  | 27.5 |  |  | (1.1 | ) |  | (4 | %)
Total |  | $ | 97.3 |  | $ | 93.0 |  | $ | 4.3 |  |  | 5 | %

Restructuring Costs. Restructuring costs of $0.0 million and $0.7 million for the quarters ended September 30, 2025 and September 30, 2024, respectively, and $1.9 million and $7.6 million for the nine months ended September 30, 2025 and September 30, 2024, respectively, were related to our restructuring plans. See Note 4 of Notes to Interim Consolidated Financial Statements included in this Report for further information regarding the restructuring plans.

Other Operating Charges, Net. We had no Other operating charges for the quarter or nine months ended September 30, 2025. Other operating charges of $0.4 million for the nine months ended September 30, 2024 represented an impairment charge on land classified as held for sale during the quarter ended March 31, 2024.

Interest Expense. See Note 6 of Notes to Interim Consolidated Financial Statements included in this Report for a discussion of our debt and credit facilities that were in effect during the quarters ended September 30, 2025 and September 30, 2024 and interest expense capitalized as part of construction in progress.

Other Income, Net. See Note 9 of Notes to Interim Consolidated Financial Statements included in this Report for details.

Income Tax Provision. See Note 10 of Notes to Interim Consolidated Financial Statements included in this Report for disclosure regarding our income tax provision.

Selected Operational and Financial Information

The following data should be read in conjunction with our consolidated financial statements and the notes thereto included in Part I, Item 1. “Financial Statements” of this Report. Interim results are not necessarily indicative of those for a full year.

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The table below provides selected operational and financial information (in millions of dollars):

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |  |  | 2025 |  |  | 2024 As Adjusted 1 |
Net income |  | $ | 39.5 |  |  | $ | 8.8 |  |  | $ | 84.3 |  |  | $ | 45.9 |
Interest expense |  |  | 12.4 |  |  |  | 10.7 |  |  |  | 36.1 |  |  |  | 33.3 |
Other income, net |  |  | (11.4 | ) |  |  | (8.7 | ) |  |  | (14.4 | ) |  |  | (19.1 | )
Income tax provision |  |  | 8.3 |  |  |  | 2.4 |  |  |  | 22.2 |  |  |  | 13.6 |
Depreciation and amortization |  |  | 32.0 |  |  |  | 29.0 |  |  |  | 91.6 |  |  |  | 86.8 |
Non-run-rate items: |  |  |  |  |  |  |  |  |  |  |  |
Restructuring costs |  |  | — |  |  |  | 0.7 |  |  |  | 1.9 |  |  |  | 7.6 |
Mark-to-market loss on derivative instruments 2 |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 2.2 |
Non-cash asset impairment charge |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.4 |
Environmental expenses 3 |  |  | 0.1 |  |  |  | 3.3 |  |  |  | 0.3 |  |  |  | 3.7 |
Loss on disposition of operating property, plant and equipment |  |  | 0.4 |  |  |  | — |  |  |  | 0.4 |  |  |  | — |
Total non-run-rate items |  |  | 0.5 |  |  |  | 4.0 |  |  |  | 2.6 |  |  |  | 13.9 |
Adjusted EBITDA 4 |  | $ | 81.3 |  |  | $ | 46.2 |  |  | $ | 222.4 |  |  | $ | 174.4 |

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 of Notes to Interim Consolidated Financial Statements included in this Report for further discussion.
2.
Mark-to-market loss on derivative instruments represents the loss on non-designated commodity hedges. Adjusted EBITDA reflects the realized impact related to these derivatives upon settlement.
3.
Non-run-rate environmental expenses are related to legacy contingencies from activities at operating facilities prior to July 6, 2006. See Note 7 of Notes to Interim Consolidated Financial Statements included in this Report for additional information relating to the environmental expenses.
4.
Adjusted EBITDA includes favorable Metal Price Lag of approximately $28.0 million and approximately $7.0 million for the quarters ended September 30, 2025 and September 30, 2024, respectively, and favorable Metal Price Lag of approximately $64.0 million and approximately $31.0 million for the nine months ended September 30, 2025 and September 30, 2024, respectively.

Adjusted EBITDA for the quarter ended September 30, 2025 was $35.1 million higher than Adjusted EBITDA for the quarter ended September 30, 2024. Adjusted EBITDA for the quarter ended September 30, 2025 was impacted by: (i) improved product pricing and mix; (ii) favorable metal costs; and (iii) lower major maintenance costs. This was partially offset by: (i) higher manufacturing costs primarily due to costs associated with the Trentwood Phase VII outage and startup of the fourth coating line at Warrick; (ii) lower sales volume; and (iii) higher employee and employee-related costs. See above in “Consolidated Results of Operations” for further details.

Adjusted EBITDA for the nine months ended September 30, 2025 was $48.0 million higher than Adjusted EBITDA for the nine months ended September 30, 2024. Adjusted EBITDA for the nine months ended September 30, 2025 was impacted by: (i) improved product pricing and mix and (ii) favorable metal costs. This was partially offset by: (i) higher manufacturing costs primarily due to costs associated with the Trentwood Phase VII outage and startup of the fourth coating line at Warrick; (ii) lower sales volume; (iii) higher employee and employee-related costs; and (iv) higher major maintenance costs. See above in “Consolidated Results of Operations” for further details.

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The following table provides our shipment and Conversion Revenue information (in millions of dollars, except shipments and Conversion Revenue per pound) by end market applications:

|  | Quarter Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Aero/HS Products: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shipments (mmlbs) |  | 41.8 |  |  | 59.5 |  |  | 158.0 |  |  | 184.6 |
|  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |
Net sales |  | $ | 182.2 |  |  | $ | 4.36 |  |  | $ | 213.1 |  |  | $ | 3.58 |  |  | $ | 624.8 |  |  | $ | 3.95 |  |  | $ | 659.7 |  |  | $ | 3.57 |
Less: Hedged Cost of Alloyed Metal |  |  | (82.7 | ) |  |  | (1.98 | ) |  |  | (85.2 | ) |  |  | (1.43 | ) |  |  | (277.6 | ) |  |  | (1.75 | ) |  |  | (261.9 | ) |  |  | (1.42 | )
Conversion Revenue |  | $ | 99.5 |  |  | $ | 2.38 |  |  | $ | 127.9 |  |  | $ | 2.15 |  |  | $ | 347.2 |  |  | $ | 2.20 |  |  | $ | 397.8 |  |  | $ | 2.15 |
Packaging: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shipments (mmlbs) |  | 144.1 |  |  | 150.9 |  |  | 415.4 |  |  | 439.2 |
|  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |
Net sales |  | $ | 393.9 |  |  | $ | 2.73 |  |  | $ | 319.5 |  |  | $ | 2.12 |  |  | $ | 1,049.0 |  |  | $ | 2.53 |  |  | $ | 930.0 |  |  | $ | 2.12 |
Less: Hedged Cost of Alloyed Metal |  |  | (256.1 | ) |  |  | (1.77 | ) |  |  | (191.1 | ) |  |  | (1.27 | ) |  |  | (654.1 | ) |  |  | (1.58 | ) |  |  | (564.7 | ) |  |  | (1.29 | )
Conversion Revenue |  | $ | 137.8 |  |  | $ | 0.96 |  |  | $ | 128.4 |  |  | $ | 0.85 |  |  | $ | 394.9 |  |  | $ | 0.95 |  |  | $ | 365.3 |  |  | $ | 0.83 |
GE Products: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shipments (mmlbs) |  | 60.4 |  |  | 55.6 |  |  | 188.9 |  |  | 173.2 |
|  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |
Net sales |  | $ | 192.2 |  |  | $ | 3.18 |  |  | $ | 150.7 |  |  | $ | 2.71 |  |  | $ | 559.2 |  |  | $ | 2.96 |  |  | $ | 466.3 |  |  | $ | 2.69 |
Less: Hedged Cost of Alloyed Metal |  |  | (110.3 | ) |  |  | (1.82 | ) |  |  | (74.6 | ) |  |  | (1.34 | ) |  |  | (308.1 | ) |  |  | (1.63 | ) |  |  | (227.4 | ) |  |  | (1.31 | )
Conversion Revenue |  | $ | 81.9 |  |  | $ | 1.36 |  |  | $ | 76.1 |  |  | $ | 1.37 |  |  | $ | 251.1 |  |  | $ | 1.33 |  |  | $ | 238.9 |  |  | $ | 1.38 |
Automotive Extrusions: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shipments (mmlbs) |  | 23.9 |  |  | 25.2 |  |  | 71.9 |  |  | 79.8 |
|  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |
Net sales |  | $ | 75.2 |  |  | $ | 3.15 |  |  | $ | 62.1 |  |  | $ | 2.45 |  |  | $ | 211.0 |  |  | $ | 2.93 |  |  | $ | 195.3 |  |  | $ | 2.45 |
Less: Hedged Cost of Alloyed Metal |  |  | (43.7 | ) |  |  | (1.83 | ) |  |  | (33.4 | ) |  |  | (1.31 | ) |  |  | (116.1 | ) |  |  | (1.61 | ) |  |  | (102.5 | ) |  |  | (1.29 | )
Conversion Revenue |  | $ | 31.5 |  |  | $ | 1.32 |  |  | $ | 28.7 |  |  | $ | 1.14 |  |  | $ | 94.9 |  |  | $ | 1.32 |  |  | $ | 92.8 |  |  | $ | 1.16 |
Other Products: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shipments (mmlbs) |  | — |  |  | 1.0 |  |  | — |  |  | 3.2 |
|  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |
Net sales |  | $ | — |  |  | $ | — |  |  | $ | 2.3 |  |  | $ | 2.30 |  |  | $ | — |  |  | $ | — |  |  | $ | 7.3 |  |  | $ | 2.28 |
Less: Hedged Cost of Alloyed Metal |  |  | — |  |  |  | — |  |  |  | (1.4 | ) |  |  | (1.40 | ) |  |  | — |  |  |  | — |  |  |  | (4.3 | ) |  |  | (1.34 | )
Conversion Revenue |  | $ | — |  |  | $ | — |  |  | $ | 0.9 |  |  | $ | 0.90 |  |  | $ | — |  |  | $ | — |  |  | $ | 3.0 |  |  | $ | 0.94 |
Total: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shipments (mmlbs) |  | 270.2 |  |  | 292.2 |  |  | 834.2 |  |  | 880.0 |
|  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |  |  | $ |  |  | $ / lb |
Net sales |  | $ | 843.5 |  |  | $ | 3.12 |  |  | $ | 747.7 |  |  | $ | 2.56 |  |  | $ | 2,444.0 |  |  | $ | 2.93 |  |  | $ | 2,258.6 |  |  | $ | 2.57 |
Less: Hedged Cost of Alloyed Metal 1 |  |  | (492.8 | ) |  |  | (1.82 | ) |  |  | (385.7 | ) |  |  | (1.32 | ) |  |  | (1,355.9 | ) |  |  | (1.63 | ) |  |  | (1,160.8 | ) |  |  | (1.32 | )
Conversion Revenue |  | $ | 350.7 |  |  | $ | 1.30 |  |  | $ | 362.0 |  |  | $ | 1.24 |  |  | $ | 1,088.1 |  |  | $ | 1.30 |  |  | $ | 1,097.8 |  |  | $ | 1.25 |

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1.
Hedged Cost of Alloyed Metal for the quarters ended September 30, 2025 and September 30, 2024 included $503.0 million and $383.6 million, respectively, reflecting the cost of aluminum at the average MWTP and the cost of certain alloys used in the production process, as well as metal price exposure on shipments that we hedged with realized gains (losses) upon settlement of $10.2 million and ($2.1) million in the quarters ended September 30, 2025 and September 30, 2024, respectively, all of which were included within both Net sales and COGS in our Statements of Consolidated Income. Hedged Cost of Alloyed Metal for the nine months ended September 30, 2025 and September 30, 2024 included $1,371.3 million and $1,158.6 million, respectively, reflecting the cost of aluminum at the average MWTP and the cost of certain alloys used in the production process, as well as metal price exposure on shipments that we hedged with realized gains (losses) upon settlement of $15.4 million and ($2.2) million in the nine months ended September 30, 2025 and September 30, 2024, respectively, all of which were included within both Net sales and COGS in our Statements of Consolidated Income. See Note 5 of Notes to Interim Consolidated Financial Statements included in this Report for the total realized gains and losses on aluminum hedges for which we hedged the metal price exposure externally.

Liquidity and Capital Resources

Summary

The following table summarizes our liquidity (in millions of dollars):

|  | As of September 30, 2025 |  |  | As of December 31, 2024 |
Available cash and cash equivalents |  | $ | 17.2 |  |  | $ | 18.4 |
Borrowing availability under Revolving Credit Facility, net of letters of credit 1 |  |  | 560.4 |  |  |  | 553.4 |
Total liquidity |  | $ | 577.6 |  |  | $ | 571.8 |

1.
Borrowing availability under the Revolving Credit Facility was determined by a borrowing base calculated as of September 30, 2025 and December 31, 2024.

We place our cash in bank deposits with high credit quality financial institutions. See Note 12 of Notes to Interim Consolidated Financial Statements included in this Report for information regarding restricted cash at September 30, 2025.

We had no outstanding borrowings under the Revolving Credit Facility as of September 30, 2025 after repaying borrowings of $290.4 million incurred during the nine months ended September 30, 2025. We had no outstanding borrowings under the Revolving Credit Facility during the year ended December 31, 2024. See below in “Sources of Liquidity” for a further discussion of subsequent borrowing activity. See Note 6 of Notes to Interim Consolidated Financial Statements included in this Report.

Cash Flows

The following table summarizes our cash flows from operating, investing, and financing activities (in millions of dollars):

|  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 As Adjusted 1 |
Total cash provided by (used in): |  |  |  |  |  |
Operating activities |  | $ | 132.0 |  |  | $ | 123.7 |
Investing activities |  | $ | (89.7 | ) |  | $ | (118.6 | )
Financing activities |  | $ | (43.2 | ) |  | $ | (41.8 | )

1.
Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 of Notes to Interim Consolidated Financial Statements included in this Report for further discussion.

Cash provided by operating activities for the nine months ended September 30, 2025 reflected results of business activity described above in our “Consolidated Results of Operations” discussion, as well as the following working capital changes: (i) an increase in accounts payable of $122.3 million, primarily due to higher metal cost; (ii) an increase in inventory of $100.4 million, primarily due to increased metal prices, partially offset by a reduction in total inventory pounds; (iii) an increase in trade and other receivables of $79.7 million, primarily due to increased metal prices; and (iv) a decrease in accrued liabilities of $28.3 million, primarily due to timing of uncleared cash disbursements and settlement of certain liabilities.

35

Cash provided by operating activities for the nine months ended September 30, 2024 reflected results of business activity described above in our “Consolidated Results of Operations” discussion, as well as the following working capital changes: (i) an increase in trade and other receivables of $33.7 million, primarily due to increased metal prices and sales mix; (ii) an increase in accounts payable of $17.5 million, primarily due to the timing of payments and higher metal cost; (iii) an increase in inventory of $8.0 million, primarily due to strong customer demand in Packaging end market; and (iv) a decrease in accrued liabilities of $11.6 million, primarily due to timing and a decrease in general business activities.

See Statements of Consolidated Cash Flows included in this Report for further details on our cash flows from operating, investing, and financing activities for the nine months ended September 30, 2025 and September 30, 2024.

Sources of Liquidity

Our most significant sources of liquidity include available cash and cash equivalents, borrowing availability under the Revolving Credit Facility, and cash flows generated from operations. We believe we have sufficient liquidity to fund our operations and meet our short-term and long-term financial obligations.

Our Revolving Credit Facility and Senior Notes have covenants that, we believe, allow us to operate our business with limited restrictions and significant flexibility for the foreseeable future. We do not believe that the covenants contained in the Revolving Credit Facility are reasonably likely to limit our ability to raise additional debt or equity should we choose to do so during the next 12 months, nor do we believe it is likely that during the next 12 months we will trigger the availability threshold that would require measuring and maintaining a fixed charge coverage ratio. On October 14, 2025, we entered into the Amended Credit Facility to, among other things, extend the maturity date to the earlier of (i) March 1, 2028, if by that date the scheduled maturity of the Company’s senior notes due 2028 has not been extended to a date not earlier than 90 days after October 14, 2030, repaid in full, or refinanced or replaced on terms mutually satisfactory to the Borrowers and Wells Fargo; and (ii) October 14, 2030, and incorporate certain improved terms offering greater operational flexibility. See Note 15 of Notes to Interim Consolidated Financial Statements included in this Report for further details.

At October 20, 2025, we had no outstanding borrowings under the Revolving Credit Facility. See Note 9 of Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2024 for a description of our Revolving Credit Facility.

We engage in certain customer-based supply chain financing programs to accelerate the receipt of payment for outstanding accounts receivable from certain customers. Costs of these programs are typically reimbursed to us by the customer. Receivables transferred under these customer-based supply chain financing programs generally meet the requirements to be accounted for as sales resulting in the derecognition of such receivables from our consolidated balance sheets. Receivables involved with these customer‑based supply chain finance programs for the quarter ended September 30, 2025 constituted approximately 31% of our Net sales. See Note 9 of Notes to Interim Consolidated Financial Statements included in this Report for further details with respect to these supply chain financing programs.

Material Cash Requirements

See Note 9 of Notes to Consolidated Financial Statements included in Part II, Item 8. “Financial Statements and Supplementary Data” in our Annual Report on Form 10-K for the year ended December 31, 2024 for mandatory principal and cash interest payments on the outstanding borrowings.

We do not believe that covenants in the indentures governing the Senior Notes are reasonably likely to limit our ability to obtain additional debt or equity financing should we choose to do so during the next 12 months.

Except as otherwise disclosed in this Report, there has been no material change in our material cash requirements from significant contractual obligations, commercial commitments, or off-balance sheet arrangements other than in the ordinary course of business since December 31, 2024.

Capital Expenditures and Investments

We strive to strengthen our competitive position across our end markets through strategic capital investment. Significant investments over the past decade have positioned us well with increased capacity and expanded manufacturing capabilities while more recent capital projects have focused on further enhancing manufacturing cost efficiency, improving product quality and promoting operational security, which we believe are critical to maintaining and strengthening our position in an increasingly competitive market

36

environment. At our Trentwood facility, a significant portion of our capital spending over the past several years related to modernization projects, which focused on equipment upgrades throughout the process flow to reduce conversion costs, increase efficiency, and further improve our competitive cost position on all products produced at Trentwood. These investments also focused on modernizing legacy equipment and the process flow for thin gauge plate to achieve Kaiser Select® quality enhancements for these Aero/HS Products and GE Products. These improvements have allowed us to gain incremental manufacturing capacity to enable future sales growth. At our Warrick facility, we have invested significant capital to expand our capacity and quality in higher margin coated products.

Our capital investment plans remain focused on supporting demand growth through capacity expansion, sustaining our operations, enhancing product quality and increasing operating efficiencies. We anticipate total capital spending in 2025 of approximately $130.0 million. We expect to continue to deploy capital thoughtfully so that investment decisions align with demand expectations in order to maximize the earnings potential of the business and maintain financial strength and flexibility.

Capital investments will be funded using cash generated from operations, available cash and cash equivalents, borrowings under the Revolving Credit Facility and/or other third-party financing arrangements. The level of anticipated capital expenditures may be adjusted from time to time depending on our business plans, our price outlook for fabricated aluminum products, our ability to maintain adequate liquidity, and other factors. No assurance can be provided as to the timing of any such expenditures or the operational benefits expected therefrom.

Dividends

We have consistently paid a quarterly cash dividend since the second quarter of 2007 to holders of our common stock, including holders of restricted stock. Nevertheless, as in the past, the future declaration and payment of dividends, if any, will be at the discretion of our Board of Directors and will depend on a number of factors, including our financial and operating results, including the availability of surplus and/or net profits, liquidity position, anticipated cash requirements and contractual restrictions under our Revolving Credit Facility, the indentures for our Senior Notes or other indebtedness we may incur in the future. We can give no assurance that dividends will be declared and paid in the future.

We also pay quarterly dividend equivalents to the holders of certain restricted stock units. Holders of performance shares are not paid a quarterly dividend equivalent, but instead are entitled to receive, in connection with the issuance of underlying shares of common stock for performance shares that ultimately vest, a one-time payment equal to the dividends such holders would have received if the number of such shares of common stock so issued had been held of record by such holders from the date of grant of such performance shares through the date of such issuance.

See our Statements of Consolidated Stockholders’ Equity and Note 15 of Notes to Interim Consolidated Financial Statements included in this Report for information regarding dividends paid during the quarters ended September 30, 2025 and September 30, 2024, and declared subsequent to September 30, 2025.

Repurchases of Common Stock

We suspended share repurchases as of March 2020. We will continue to assess share repurchases as a part of our capital allocation priorities and strategic investment opportunities identified to support further growth in our business. At September 30, 2025, $93.1 million remained authorized and available for future repurchases of common stock under our stock repurchase program.

See our Statements of Consolidated Stockholders’ Equity included in this Report for information regarding minimum statutory tax withholding obligations arising during the quarters ended September 30, 2025 and September 30, 2024 in connection with the vesting of non‑vested shares, restricted stock units, and performance shares.

Critical Accounting Estimates and Policies

Our consolidated financial statements are prepared in accordance with GAAP. In connection with the preparation of our financial statements, we are required to make assumptions and estimates about future events and apply judgments that affect the reported amounts of assets, liabilities, revenue and expenses and the related disclosures. We base our assumptions, estimates and judgments on historical experience, current trends and other factors that management believes to be relevant at the time our consolidated financial statements are prepared. On a regular basis, management reviews the accounting policies, assumptions, estimates and judgments to ensure that our financial statements are presented fairly and in accordance with GAAP. However, because future events and their effects cannot be determined with certainty, actual results could differ from our assumptions and estimates and such differences could be material.

37

Our significant accounting policies are discussed in Note 1 of Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2024. We discuss our critical accounting estimates in Part II, Item 7. “Management’s Discussion and Analysis of Financial Condition and Results of Operations” of our Annual Report on Form 10‑K for the year ended December 31, 2024. There have been no material changes in our critical accounting estimates and policies since December 31, 2024.

New Accounting Pronouncements

Information regarding new accounting pronouncements is included in Note 1 of our Interim Consolidated Financial Statements in this Form 10-Q.

Availability of Information

We file Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, Proxy Statements, any amendments to those reports and statements and other information with the SEC. You may obtain the documents that we file electronically from the SEC’s website at http://www.sec.gov. Our filings with the SEC are made available free of charge on our website at http://www.kaiseraluminum.com as soon as reasonably practicable after we file or furnish the materials with the SEC. News releases, announcements of upcoming earnings calls and events in which our management participates or hosts with members of the investment community and an archive of webcasts of such earnings calls and investor events and related investor presentations, are also available on our website. Information on our website is not incorporated into this Form 10-Q unless expressly noted.

Item 3. Quantitative and Qualitat ive Disclosures About Market Risk

The following quantitative and qualitative disclosures about market risk should be read in conjunction with Note 5 and Note 8 of Notes to Interim Consolidated Financial Statements included in this Report. Our operating results are sensitive to changes in the prices of primary aluminum, certain alloying metals, natural gas, electricity, and foreign currency, and also depend to a significant degree upon the volume and mix of products sold to customers. We have historically utilized hedging transactions to lock in a specified price or range of prices for certain products which we sell or consume in our production process, and to mitigate our exposure to changes in energy prices.

Aluminum

During the nine months ended September 30, 2025 and September 30, 2024, settlements of derivative contracts were for 88.8 million pounds and 117.3 million pounds, respectively, of hedged shipments sold on pricing terms that created aluminum price risk for us. At September 30, 2025, we had derivative contracts with respect to approximately 34.6 million and 6.0 million pounds to hedge sales to be made in the remainder of 2025 and 2026, respectively, on pricing terms that create aluminum price risk for us.

Based on the aluminum derivative positions held by us to hedge firm-price customer sales agreements, we estimate that a $0.10/lb decrease in the LME market price of aluminum as of September 30, 2025 and December 31, 2024, with all other variables held constant, would have resulted in an unrealized mark-to-market loss of $4.1 million and $4.7 million, respectively, with corresponding changes to the net fair value of our aluminum derivative positions. Additionally, we estimate that a $0.05/lb decrease in the Midwest premium for aluminum as of September 30, 2025 and December 31, 2024, with all other variables held constant, would have resulted in an unrealized mark-to-market loss of $2.0 million and $2.0 million, respectively, with corresponding changes to the net fair value of our aluminum derivative positions.

Alloying Metals

We are exposed to the risk of fluctuating prices of certain alloying metals, especially copper, zinc, and magnesium, to the extent that changes in their prices do not highly correlate with price changes for aluminum. Copper, zinc, magnesium, and certain other metals are used in our remelt operations to cast rolling ingot and extrusion billet with the proper chemistry for our products. From time to time, we enter into forward contract swaps and/or physical delivery commitments with third parties to mitigate our risk from fluctuations in the prices of these alloys. As of September 30, 2025, we had forward swap contracts with settlement dates designed to align with the timing of scheduled purchases of zinc and copper by our manufacturing facilities. We estimate that a $0.10/lb decrease in the market price of zinc and copper as of September 30, 2025 and December 31, 2024, with all other variables held constant, would have resulted in an unrealized mark‑to‑market loss of $0.7 million and $0.9 million, respectively, with corresponding changes to the net fair value of our zinc and copper derivative positions.

38

Energy

We are exposed to the risk of fluctuating prices for natural gas and electricity. We, from time to time, in the ordinary course of business, enter into hedging transactions and/or firm-price physical delivery commitments with third parties to mitigate our risk from fluctuations in natural gas and electricity prices. We estimate that a $1.00 per mmbtu decrease in natural gas prices would have resulted in an unrealized mark-to-market loss of $3.3 million and $2.8 million as of September 30, 2025 and December 31, 2024, respectively, with corresponding changes to the net fair value of our natural gas derivative positions. We had no outstanding electricity derivative positions as of September 30, 2025 and December 31, 2024.

Foreign Currency

As of September 30, 2025, we hedged the foreign currency exchange rate risk related to certain lease transactions and equipment purchases denominated in Euros using forward swap contracts with settlement dates through July 2027. We estimate that a 10% decrease in the exchange rate of our hedged foreign currencies to U.S. dollars would have resulted in an unrealized mark-to-market loss of $0.2 million and $0.8 million as of September 30, 2025 and December 31, 2024, respectively, with corresponding changes to the net fair value of our foreign currency derivative positions.

Item 4. Controls and Procedures

Evaluation of Disclosure Controls and Procedures. We maintain disclosure controls and procedures that are designed to ensure that information required to be disclosed in our reports under the Securities Exchange Act of 1934 is processed, recorded, summarized and reported within the time periods specified in the SEC’s rules and forms and that such information is accumulated and communicated to management, including the principal executive officer and principal financial officer, to allow for timely decisions regarding required disclosure. In designing and evaluating the disclosure controls and procedures, management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives, and management is required to apply its judgment in evaluating the cost-benefit relationship of possible controls and procedures. An evaluation of the effectiveness of the design and operation of our disclosure controls and procedures was performed as of the end of the period covered by this Report under the supervision of and with the participation of our management, including the principal executive officer and principal financial officer. Based on that evaluation, our principal executive officer and principal financial officer concluded that our disclosure controls and procedures were effective as of September 30, 2025 at the reasonable assurance level.

Changes in Internal Control Over Financial Reporting. We had no changes in our internal control over financial reporting during the nine months ended September 30, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

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PART II – OTH ER INFORMATION

Item 1. Legal Proceedings

Reference is made to Part I, Item 3. “Legal Proceedings” included in our Annual Report on Form 10-K for the year ended December 31, 2024 for information concerning material legal proceedings with respect to the Company. There have been no material developments since December 31, 2024.

Item 1A. Ri sk Factors

Reference is made to Part I, Item 1A. “Risk Factors” included in our Annual Report on Form 10-K for the year ended December 31, 2024 for information concerning risk factors. There have been no material changes in risk factors since December 31, 2024.

Item 2. Unregistered Sales of Equi ty Securities and Use of Proceeds

The following table provides information regarding our repurchases of our common shares during the quarter ended September 30, 2025:

|  | Equity Incentive Plan |  |  | Stock Repurchase Plan |
|  | Total Number of Shares Purchased 1 |  |  | Average Price per Share |  |  | Total Number of Shares Purchased 2 |  |  | Average Price per Share |  |  | Maximum Dollar Value of Shares that May Yet Be Purchased Under the Programs (millions)2 |
July 1, 2025 - July 31, 2025 |  |  | 103 |  |  | $ | 88.48 |  |  |  | — |  |  | $ | — |  |  | $ | 93.1 |
August 1, 2025 - August 31, 2025 |  |  | 14,275 |  |  |  | 74.73 |  |  |  | — |  |  |  | — |  |  |  | 93.1 |
September 1, 2025 - September 30, 2025 |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 93.1 |
Total |  |  | 14,378 |  |  | $ | 74.83 |  |  |  | — |  |  | $ | — |  |  | n/a |

1.
Under our equity incentive plan, participants may elect to have us withhold common shares to satisfy minimum statutory tax withholding obligations arising from the recognition of income and the vesting of restricted stock, restricted stock units, and performance shares. When we withhold these shares, we are required to remit to the appropriate taxing authorities the market price of the shares withheld by us on the date of withholding. The withholding of common shares by us could be deemed a purchase of such common shares.
2.
In September 2018, our Board of Directors authorized us to repurchase an indeterminate number of shares of our common stock at an aggregate market value of up to $100.0 million. At September 30, 2025, $93.1 million remained available to repurchase our common shares pursuant to the stock repurchase program. The September 2018 authorization does not have an expiration date.

Item 3. Defaults Upo n Senior Securities

None.

Item 4. Mine Saf ety Disclosures

Not applicable.

Item 5. Other Information

Rule 10b5-1 Trading Arrangements. During the quarter ended September 30, 2025, no director or officer of the Company adopted, modified, or terminated a "Rule 10b5-1 trading arrangement" or "non-Rule 10b5-1 trading arrangement" as each term is defined in Item 408 of Regulation S-K.

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*Item 6. Exhibits

Exhibit |  |  |  | Provided |  | Incorporated by Reference
No. |  | Exhibit Description |  | Herewith |  | Form |  | File Number |  | Exhibit |  | Filing Date
10.1 |  | Amendment No. 5 to Credit Agreement and Loan Documents, dated as of October 14, 2025, by and among the Company and certain affiliates of the Company, as borrowers, Wells Fargo Bank, National Association, as agent for the lenders, and the lenders party thereto |  | X |  |  |  |  |  |  |  |
31.1 |  | Certification of Keith A. Harvey pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 |  | X |  |  |  |  |  |  |  |
31.2 |  | Certification of Neal E. West pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 |  | X |  |  |  |  |  |  |  |
32.1 |  | Certification of Keith A. Harvey pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 |  | X |  |  |  |  |  |  |  |
32.2 |  | Certification of Neal E. West pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 |  | X |  |  |  |  |  |  |  |
101.INS |  | Inline XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document |  |  |  |  |  |  |  |  |  |
101.SCH |  | Inline XBRL Taxonomy Extension Schema |  | X |  |  |  |  |  |  |  |
104 |  | Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101) |  | X |  |  |  |  |  |  |  |

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SIGNA TURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this Report to be signed on its behalf by the undersigned thereunto duly authorized.

| KAISER ALUMINUM CORPORATION
| /s/ Neal E. West
| Neal E. West
| Executive Vice President and Chief Financial Officer (Principal Financial Officer)
| /s/ Vijai Narayan
| Vijai Narayan
| Vice President and Chief Accounting Officer (Principal Accounting Officer)

Date: October 23, 2025

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