CENTURY ALUMINUM CO

Condensed Notes to the Consolidated Financial Statements

Three months ended March 31, 2024 and 2023

1. General

The accompanying unaudited interim consolidated financial statements of Century Aluminum Company should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2023. In management’s opinion, the unaudited interim consolidated financial statements reflect all adjustments, which are of a normal and recurring nature, that are necessary for a fair presentation of financial results for the interim periods presented. Operating results for the first three months of 2024 are not necessarily indicative of the results that may be expected for the year ending December 31, 2024. Throughout this Form 10-Q, and unless expressly stated otherwise or as the context otherwise requires, "Century Aluminum", "Century", "the Company", "we", "us", "our" and "ours" refer to Century Aluminum Company and its consolidated subsidiaries.

Our consolidated financial statements include the consolidated results of the Jamalco joint venture, an unincorporated joint venture between the Company and Clarendon Alumina Production Limited. Clarendon Alumina Production's interest in the joint venture is reflected as noncontrolling interest on the accompanying Consolidated Balance Sheets.

Recently Issued Accounting Standards

In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) 2023-07, “Improvements to Reportable Segment Disclosures.” (“ASU 2023-07”). Among other changes, the ASU requires disclosure of significant segment expenses and extends certain annual disclosures to interim periods. The ASU is effective for the Company beginning with its annual financial statements for the year ending December 31, 2024. Early adoption is permitted. The Company is currently evaluating the requirements of ASU 2023-07.

2. Acquisition of Jamalco

On May 2, 2023, our wholly-owned subsidiary, Century Aluminum Jamaica Holdings, Inc., completed the acquisition of all the outstanding share capital of General Alumina Holdings Limited, the holder of a 55% interest in Jamalco JV ("Jamalco"), an unincorporated joint venture engaged in bauxite mining and alumina production in Jamaica. The remaining 45% interest in Jamalco is owned by Clarendon Alumina Production Limited ("CAP"), which is owned by the Government of Jamaica. The results of operations have been included in the consolidated financial statements since the acquisition date. The purchase price of the acquisition was $1.00, primarily due to the seller experiencing financial distress following curtailment of Jamalco's operations in the second half of 2021 due to a facility fire, with operations restarting in the second half of 2022.

The acquisition was accounted for as a business combination under the acquisition method of accounting in accordance with ASC 805 - Business Combinations, resulting in the Company recognizing the assets and liabilities at fair value with the excess over fair value of consideration transferred to the seller presented as a bargain purchase gain of $245.9 million recognized within the Consolidated Statements of Operations for the three months ended March 31, 2024. The Company finalized its purchase accounting as of March 31, 2024.

The following table represents the allocation of the estimated fair value of identified assets acquired, liabilities assumed and noncontrolling interest as of March 31, 2024

The following unaudited pro forma financial information reflects the results of operations of the Company for the three months ended March 31, 2023 as if the acquisition of Jamalco had been completed on January 1, 2023. This unaudited pro forma financial information has been prepared for informational purposes and is not necessarily indicative of the actual consolidated results of operations had the acquisition been completed on January 1, 2023, nor is the information indicative of future results of operations of the combined companies.

3. Curtailment of Operations - Hawesville

In August 2022, we fully curtailed production at the Hawesville facility and expect to continue to maintain the plant with the intention of restarting operations when market conditions permit, including energy prices returning to more normalized levels and aluminum prices maintaining levels that can support the on-going costs and capital expenditures necessary to restart and operate the plant.

For the three months ended March 31, 2024 and 2023, we incurred curtailment charges of approximately $0.6 million and $7.0 million, respectively, including $5.4 million related to demand capacity charges for power during three months ended March 31, 2023. In addition, these charges were partially offset by income related to scrap and materials sales of $0.5 million and $0.7 million for the three months ended March 31, 2024 and 2023, respectively, recognized in Other operating expense - net within the Consolidated Statements of Operations.

4. Related Party Transactions

The significant related party transactions occurring during the three months ended March 31, 2024 and 2023 are described below. We believe all of our transactions with related parties are at prices that approximate market.

Glencore Ownership

As of March 31, 2024, Glencore plc and its affiliates (together "Glencore") beneficially owned 42.9% of Century’s outstanding common stock (46.0% on a fully-diluted basis assuming the conversion of all of the Series A Convertible Preferred Stock) and all of our outstanding Series A Convertible Preferred Stock. See Note 8. Shareholders' Equity for a description of our outstanding Series A Convertible Preferred Stock. Century and Glencore enter into various transactions from time to time such as the purchase and sale of primary aluminum, purchase and sale of alumina and other raw materials, tolling agreements as well as forward financial contracts and borrowing and other debt transactions.

Sales to Glencore

For thethree months ended March 31, 2024 and 2023, we derived approximately 64.3% and 75.0% of our consolidated net sales from Glencore, respectively.

Glencore purchases aluminum produced at our U.S. smelters at prices based on the LME plus the Midwest regional delivery premium plus any additional market-based product premiums. Glencore purchases aluminum produced at our Grundartangi, Iceland smelter at prices primarily based on the LME plus the European Duty Paid premium plus any additional market-based product premiums.

We have entered into agreements with Glencore pursuant to which we sell certain amounts of alumina at market-based prices. For the three months ended March 31, 2024 and 2023, the Company recognized $35.5 million and$21.0 million, respectively, of revenue related to alumina sales to Glencore.

Purchases from Glencore

We purchase a portion of our alumina and certain other raw material requirements from Glencore. Alumina purchases from Glencore during the three months ended March 31, 2024 and March 31, 2023, were priced based on published alumina and aluminum indices as well as fixed prices.

Financial Contracts with Glencore

We have certain financial contracts with Glencore. See Note 15. Derivatives regarding these forward financial sales contracts.

Summary

A summary of the aforementioned significant related party sales and purchases is as follows:

(1)Includes settlements of financial contract positions.

On December 9, 2022, Vlissingen entered into a Facility Agreement with Glencore International AG pursuant to which Vlissingen may borrow from time to time up to $90.0 million (the "Vlissingen Facility Agreement") in one or more loans at a fixed interest rate equal to 8.75% per annum and payable on December 2, 2024. See Note 11. Debt for additional information. Borrowings under the Vlissingen Facility Agreement are expected to be used for general corporate and working capital purposes of Century and its subsidiaries.

Carbon Credit Repurchase Agreement

In September 2023, our wholly owned subsidiary Nordural Grundartangi ehf ("Grundartangi"), entered into a structured repurchase arrangement ("Agreement") with an affiliate of Glencore and sold 390,000 European Union Allowances ("Carbon Credits") at a price of €82.18 per Carbon Credit, for an aggregate amount of €32.1 million. The terms of the transaction permitted Grundartangi to repurchase the same number of Carbon Credits by December 21, 2023, at a price of€83.72 per Carbon Credit, for an aggregate amount of€32.7 million. In December 2023, the Agreement was amended ("Amended Agreement") to extend the repurchase window to March 25, 2024, and increased the repurchase price to €85.13 per Carbon Credit, for an aggregate amount of €33.2 million. In addition, Grundartangi entered into a second repurchase agreement ("Second Agreement") with Glencore to sell 40,000 Carbon Credits at a price of €69.30 per Carbon Credit and to repurchase the same number of Carbon Credits at a price of €70.71 per Carbon Credit for an aggregate amount of €2.8 million.

In March 2024, the Amended Agreement was amended to extend the repurchase window from March 25, 2024 to August 30, 2024 and the repurchase price was revised to €87.01 per Carbon Credit, for an aggregate amount of €33.9 million. In addition, the Second Agreement was amended to extend the repurchase window from March 25, 2024 to August 30, 2024 and revised the repurchase price to €72.59 per Carbon Credit, for an aggregate amount of €2.9 million. Due to the repurchase element of these transactions, the Company retains substantially all of the remaining benefits of the assets and has accounted for the transaction as a financing arrangement in accordance with Topic 606, Revenue from Contracts with Customers ("ASC 606").

5. Revenue

We disaggregate our revenue by geographical region as follows:

We enter into contracts to sell mainly primary aluminum to our customers. Revenue is recognized when our performance obligations with our customers are satisfied. Our obligations under the contracts are satisfied when we transfer control of our primary aluminum to our customers which is generally upon shipment or delivery to customer directed locations. The amount of consideration we receive, thus the revenue we recognize, is a function of volume delivered, market price of primary aluminum, which is based on the LME, plus regional premiums and any value-added product premiums. We have also entered into agreements with our customers to sell certain amounts of alumina at market-based prices.

The payment terms and conditions in our contracts vary and are not significant to our revenue. We complete an appropriate credit evaluation for each customer at contract inception. Customer payments are due in arrears and are recognized as accounts receivable - net and due from affiliates in our consolidated balance sheets.

In connection with our sales agreements with certain customers, including Glencore, we invoice the customer prior to physical shipment of goods for a majority of production generated from each of our U.S. domestic smelters. For those sales, revenue is recognized only when the customer has specifically requested such treatment and has made a commitment to purchase the product. The goods must be complete, ready for shipment and separated from other inventory with control over the goods passing to the customer. We must retain no further performance obligations.

Contract liabilities are recorded when cash payments are received or due in advance of performance. Amounts recognized in Due to affiliates was $52.0 million and $30.6 million, as of March 31, 2024 and December 31, 2023, respectively.

6. Fair Value Measurements

We measure certain of our assets and liabilities at fair value. Fair value represents the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

In general, reporting entities should apply valuation techniques to measure fair value that maximize the use of observable inputs and minimize the use of unobservable inputs. Observable inputs are developed using market data and reflect assumptions that market participants would use when pricing the asset or liability. Unobservable inputs are developed using the best information available about the assumptions that market participants would use when pricing the asset or liability.

The fair value hierarchy provides transparency regarding the inputs we use to measure fair value. We categorize each fair value measurement in its entirety into the following three levels, based on the lowest level input that is significant to the entire measurement:

•Level 1 Inputs - quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity can access at the measurement date.

•Level 2 Inputs - inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

•Level 3 Inputs - unobservable inputs for the asset or liability.

(1)Trust assets are currently invested in money market funds. These trust assets are held to fund the non-qualified supplemental executive pension benefit obligations for certain of our officers.

The following section describes the valuation techniques and inputs for fair value measurements categorized within Level 2 of the fair value hierarchy:

When valuing Level 3 assets and liabilities, we use certain significant unobservable inputs. Management incorporates various inputs and assumptions including forward commodity prices, commodity price volatility and macroeconomic conditions, including interest rates and discount rates. Our estimates of significant unobservable inputs are ultimately based on our estimates of risks that market participants would consider when valuing our assets and liabilities.

The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis. There was no activity related to Level 3 assets and liabilities measured at fair value on a recurring basis for the three months ended March 31, 2024.

(1)Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts."

(2)Transfers into Level 3 due to period of time remaining in derivative contract.

7. Earnings Per Share

Basic and diluted earnings per share ("EPS") amounts are calculated using the two-class method. Under the two-class method, net earnings are allocated to each class of common stock and participating securities as if all of the net earnings for the period had been distributed. Basic earnings per common share excludes dilution and is calculated by dividing net income (loss) allocated to common stockholders by the weighted average number of common shares outstanding during the period. Diluted EPS amounts assume the issuance of common stock for all potentially dilutive securities. Prior to the three months ended March 31, 2024, diluted EPS amounts were calculated by applying the if-converted method as net income allocated to participating securities was not significant.

The following table shows the basic and diluted (loss) earnings per share:

(1)In periods when we report a net loss, all share-based compensation awards, convertible preferred shares and convertible senior notes are excluded from the calculation of diluted weighted average shares outstanding because of their anti-dilutive effect on earnings (loss) per share.