KAISER ALUMINUM CORP

9. Debt and Credit Facility

Senior Notes

Issuance of $500.0 million Senior Notes Due 2034. In November 2025, we issued $500.0 million aggregate principal amount of our 5.875% unsecured senior notes due March 1, 2034 (“5.875% Senior Notes”) at par. The 5.875% Senior Notes bear interest at a rate of 5.875% per annum, payable semi-annually on March 1 and September 1, beginning in March 2026. Upon certain asset sales or changes in control accompanied by a ratings decline, we may be required to offer to repurchase the 5.875% Senior Notes. The indenture includes customary covenants and events of default provisions. In the event of default, the trustee or holders of at least 25% in aggregate principal amount of the 5.875% Senior Notes may declare the entire principal amount and the interest accrued to be immediately due and payable.

Redemption of $500.0 million Senior Notes Due 2028. In November 2025, we redeemed all $500.0 million aggregate principal amount of our outstanding 4.625% unsecured senior notes (“4.625% Senior Notes”) at a redemption price of 100% of the principal amount thereof, plus accrued and unpaid interest. The redemption was funded using the net proceeds from the issuance of the 5.875% Senior Notes (as further described above), together with existing cash on hand and borrowings under the Revolving Credit Facility. In connection with the redemption of the 4.625% Senior Notes, during the year ended December 31, 2025, we wrote-off the remaining unamortized debt issuance costs of $2.1 million within Other income, net in our Statements of Consolidated Income.

Senior Notes Outstanding. During the years ended December 31, 2025 and 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; (ii)4.50% and $550.0 million (“4.50% Senior Notes”); and (iii)5.875% and $500.0 million. Our Senior Notes do not require us to make any mandatory redemptions or sinking fund payments. The following table summarizes key details of our outstanding Senior Notes:

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

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.

In October 2025, we entered into amendment No. 5 to our Revolving Credit Facility. As amended, the Revolving Credit Facility is set to mature in October 2030, and, 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) and (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 of one or more lenders to provide such increased commitment. The amount we can borrow under the Revolving Credit Facility is determined by the value of our eligible accounts receivable and inventory and certain other assets, which serve as collateral for the Revolving Credit Facility. Borrowings under the amended Revolving Credit Facility bear interest at a rate equal to either a base rate or the SOFR, plus, in each case, a specified variable percentage between 125 -150 basis points for SOFR loans (or 25 -50 basis points for base rate loans) determined by reference to the then-remaining borrowing availability under the Revolving Credit Facility and, in certain instances, a fixed margin. Outstanding borrowings under the Revolving Credit Facility are reported within Long-term debt, net, on our Consolidated Balance Sheets. We had $22.3 million of outstanding borrowings under our Revolving Credit Facility as of December 31, 2025, reflecting borrowings of $653.3 million and repayments of $631.0 million during the year ended December 31, 2025. We hadno outstanding borrowings under our 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 December 31, 2025 (in millions of dollars):

Interest Expense and Future Maturities

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

The following table presents the future principal payments for our Senior Notes and Revolving Credit Facility as of December 31, 2025 (in millions of dollars):