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STATEMENTS OF CONSOLIDATED STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions | Total | Common Stock | Additional Paid in Capital | Retained Earnings | Treasury Stock | Accumulated Other Comprehensive Income (Loss)
--- | --- | --- | --- | --- | --- | ---
Beginning balance at Dec. 31, 2023 |  | $ 652.2 | [1] | $ 0.2 |  | $ 1,104.7 | $ 10.1 | [1] | $ (475.9) | $ 13.1
Beginning balance (Cumulative Effect of Change in Inventory Valuation Methodology, Net of Tax) at Dec. 31, 2023 | [1] | 56.2 |  |  |  |  | 56.2 |  |  |
Beginning balance (shares) at Dec. 31, 2023 |  |  |  | 16,015,791 |  |  |  |  |  |
Net income | [1] | 18.2 |  |  |  |  | 18.2 |  |  |
Other comprehensive (loss) income, net of tax |  | (2.1) | [1] |  |  |  |  |  |  | (2.1)
Common shares issued (including impacts from Long-Term Incentive programs) (shares) |  |  |  | 56,416 |  |  |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued |  | (1.2) | [1] |  |  | (1.2) |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued (shares) |  |  |  | (16,175) |  |  |  |  |  |
Cash dividends declared | [1],[2] | (12.6) |  |  |  |  | (12.6) |  |  |
Amortization of unearned equity compensation |  | 4.0 | [1] |  |  | 4.0 |  |  |  |
Ending balance at Mar. 31, 2024 | [1] | 714.7 |  | $ 0.2 |  | 1,107.5 | 71.9 |  | (475.9) | 11.0
Ending balance (shares) at Mar. 31, 2024 | [1] |  |  | 16,056,032 |  |  |  |  |  |
Beginning balance at Dec. 31, 2023 |  | 652.2 | [1] | $ 0.2 |  | 1,104.7 | 10.1 | [1] | (475.9) | 13.1
Beginning balance (Cumulative Effect of Change in Inventory Valuation Methodology, Net of Tax) at Dec. 31, 2023 | [1] | 56.2 |  |  |  |  | 56.2 |  |  |
Beginning balance (shares) at Dec. 31, 2023 |  |  |  | 16,015,791 |  |  |  |  |  |
Net income | [3],[4],[5] | 45.9 |  |  |  |  |  |  |  |
Other comprehensive (loss) income, net of tax | [4] | 3.2 |  |  |  |  |  |  |  |
Ending balance at Sep. 30, 2024 |  | 729.4 | [1] | $ 0.2 |  | 1,114.6 | 74.2 | [1] | (475.9) | 16.3
Ending balance (shares) at Sep. 30, 2024 |  |  |  | 16,087,755 |  |  |  |  |  |
Beginning balance at Mar. 31, 2024 | [1] | 714.7 |  | $ 0.2 |  | 1,107.5 | 71.9 |  | (475.9) | 11.0
Beginning balance (shares) at Mar. 31, 2024 | [1] |  |  | 16,056,032 |  |  |  |  |  |
Net income | [1] | 18.9 |  |  |  |  | 18.9 |  |  |
Other comprehensive (loss) income, net of tax |  | 3.2 | [1] |  |  |  |  |  |  | 3.2
Common shares issued (including impacts from Long-Term Incentive programs) |  | 0.5 | [1] |  |  | 0.5 |  |  |  |
Common shares issued (including impacts from Long-Term Incentive programs) (shares) |  |  |  | 38,143 |  |  |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued |  | (0.6) | [1] |  |  | (0.6) |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued (shares) |  |  |  | (7,063) |  |  |  |  |  |
Cash dividends declared | [1] | (12.7) |  |  |  |  | (12.7) |  |  |
Amortization of unearned equity compensation |  | 3.6 | [1] |  |  | 3.6 |  |  |  |
Ending balance at Jun. 30, 2024 | [1] | 727.6 |  | $ 0.2 |  | 1,111.0 | 78.1 |  | (475.9) | 14.2
Ending balance (shares) at Jun. 30, 2024 | [1] |  |  | 16,087,112 |  |  |  |  |  |
Net income |  | 8.8 | [3],[4] |  |  |  | 8.8 | [1] |  |
Other comprehensive (loss) income, net of tax |  | 2.1 | [4] |  |  |  |  |  |  | 2.1
Common shares issued (including impacts from Long-Term Incentive programs) |  | 0.1 | [1] |  |  | 0.1 |  |  |  |
Common shares issued (including impacts from Long-Term Incentive programs) (shares) |  |  |  | 1,000 |  |  |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued (shares) |  |  |  | (357) |  |  |  |  |  |
Cash dividends declared | [1] | (12.7) |  |  |  |  | (12.7) |  |  |
Amortization of unearned equity compensation |  | 3.5 | [1] |  |  | 3.5 |  |  |  |
Ending balance at Sep. 30, 2024 |  | 729.4 | [1] | $ 0.2 |  | 1,114.6 | 74.2 | [1] | (475.9) | 16.3
Ending balance (shares) at Sep. 30, 2024 |  |  |  | 16,087,755 |  |  |  |  |  |
Beginning balance at Dec. 31, 2024 | [6] | $ 743.1 | [7] | $ 0.2 |  | 1,117.0 | 81.3 |  | (475.9) | 20.5
Beginning balance (shares) at Dec. 31, 2024 |  | 16,095,898 |  | 16,095,898 | [6],[8] |  |  |  |  |
Net income |  | $ 21.6 |  |  |  |  | 21.6 |  |  |
Other comprehensive (loss) income, net of tax |  | 2.6 |  |  |  |  |  |  |  | 2.6
Common shares issued (including impacts from Long-Term Incentive programs) (shares) | [8] |  |  | 84,115 |  |  |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued |  | (1.8) |  |  |  | (1.8) |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued (shares) | [8] |  |  | (25,637) |  |  |  |  |  |
Cash dividends declared | [9] | (12.9) |  |  |  |  | (12.9) |  |  |
Amortization of unearned equity compensation |  | 4.2 |  |  |  | 4.2 |  |  |  |
Ending balance at Mar. 31, 2025 |  | 756.8 |  | $ 0.2 |  | 1,119.4 | 90.0 |  | (475.9) | 23.1
Ending balance (shares) at Mar. 31, 2025 | [8] |  |  | 16,154,376 |  |  |  |  |  |
Beginning balance at Dec. 31, 2024 | [6] | $ 743.1 | [7] | $ 0.2 |  | 1,117.0 | 81.3 |  | (475.9) | 20.5
Beginning balance (shares) at Dec. 31, 2024 |  | 16,095,898 |  | 16,095,898 | [6],[8] |  |  |  |  |
Net income | [5] | $ 84.3 |  |  |  |  |  |  |  |
Other comprehensive (loss) income, net of tax |  | 6.2 |  |  |  |  |  |  |  |
Ending balance at Sep. 30, 2025 |  | $ 806.1 |  | $ 0.2 |  | 1,128.0 | 127.1 |  | (475.9) | 26.7
Ending balance (shares) at Sep. 30, 2025 |  | 16,206,255 |  | 16,206,255 | [8] |  |  |  |  |
Beginning balance at Mar. 31, 2025 |  | $ 756.8 |  | $ 0.2 |  | 1,119.4 | 90.0 |  | (475.9) | 23.1
Beginning balance (shares) at Mar. 31, 2025 | [8] |  |  | 16,154,376 |  |  |  |  |  |
Net income |  | 23.2 |  |  |  |  | 23.2 |  |  |
Other comprehensive (loss) income, net of tax |  | 4.1 |  |  |  |  |  |  |  | 4.1
Common shares issued (including impacts from Long-Term Incentive programs) |  | 0.4 |  |  |  | 0.4 |  |  |  |
Common shares issued (including impacts from Long-Term Incentive programs) (shares) | [8] |  |  | 23,582 |  |  |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued (shares) | [8] |  |  | (219) |  |  |  |  |  |
Cash dividends declared | [6] | (12.8) |  |  |  |  | (12.8) |  |  |
Amortization of unearned equity compensation |  | 4.3 |  |  |  | 4.3 |  |  |  |
Ending balance at Jun. 30, 2025 |  | 776.0 |  | $ 0.2 |  | 1,124.1 | 100.4 |  | (475.9) | 27.2
Ending balance (shares) at Jun. 30, 2025 | [8] |  |  | 16,177,739 |  |  |  |  |  |
Net income |  | 39.5 |  |  |  |  | 39.5 |  |  |
Other comprehensive (loss) income, net of tax |  | (0.5) |  |  |  |  |  |  |  | (0.5)
Common shares issued (including impacts from Long-Term Incentive programs) |  | 0.1 |  |  |  | 0.1 |  |  |  |
Common shares issued (including impacts from Long-Term Incentive programs) (shares) | [8] |  |  | 42,894 |  |  |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued |  | (1.1) |  |  |  | (1.1) |  |  |  |
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares/common shares issued (shares) | [8] |  |  | (14,378) |  |  |  |  |  |
Cash dividends declared | [6] | (12.8) |  |  |  |  | (12.8) |  |  |
Amortization of unearned equity compensation |  | 4.9 |  |  |  | 4.9 |  |  |  |
Ending balance at Sep. 30, 2025 |  | $ 806.1 |  | $ 0.2 |  | $ 1,128.0 | $ 127.1 |  | $ (475.9) | $ 26.7
Ending balance (shares) at Sep. 30, 2025 |  | 16,206,255 |  | 16,206,255 | [8] |  |  |  |  |
[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.
[3] | Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
[4] | Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
[5] | See Note 12 for supplemental cash flow information.
[6] | Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
[7] | Adjusted to reflect the retrospective change in inventory valuation methodology from LIFO to WAC. See Note 14 for further discussion.
[8] | 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.
[9] | Dividends declared per common share were $0.77 for each of the quarters ended March 31, 2025, June 30, 2025, and September 30, 2025.

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