Century Aluminum : 2021 Chairman's Letter

Andrew Michelmore	Michael Bless
Chairman of the Board	President and Chief Executive Officer

Dear Fellow Shareholder,

As we reflect upon an extraordinary year for our company, our industry and the world in general, it is necessary and appropriate to begin with consideration of our foremost responsibility -- ensuring the safety and well-being of our employees and all visitors to Century facilities. Sadly, we suffered two fatalities during 2020. One tragedy occurred in April at Sebree; the other took place at Mt. Holly in December. We continue to hold our late colleagues and their families in our thoughts and prayers. These losses remain painful for our employees, and for the tight-knit communities in which these plants are located. They have caused deep reflection amongst Century's directors, management and employees. We are examining all facets of our safety and health systems. We have recently adopted new vision and policy statements reiterating and redefining our commitment to safety; we have also implemented a comprehensive safety leadership program that drives two-way communication and coaching throughout the organization. Our team is totally focused on and committed to achieving consistent improvement in our most fundamental responsibility.

We are proud that our plants have operated continuously throughout the pandemic. Our site leadership was quick to implement strict protocols and mitigation measures at all of our locations; many of these measures remain in place as we wait for the pandemic to abate. This regimen has required meaningful sacrifices from our people. We have benefited from the unwavering support of our communities, in which our plants are critical employers. We are also thankful for the consistent support of our customers, suppliers, shareholders and other key stakeholders. Century has suffered no serious COVID-related hospitalizations. We have asked for our employees' continued sacrifice in maintaining their vigilance as we approach what we all hope to be the endgame of the acute phase of the pandemic.

We were pleased to have reached a new three-year power agreement for Mt. Holly. Service under this contract is provided solely by the South Carolina Public Service Authority (Santee Cooper) and is of a magnitude that will allow us to increase the smelter's production to 75 percent of capacity (from the 50 percent level at which we have been operating during the past several years). The new arrangement will enable us to make the necessary investments to bring Mt. Holly to the standard this excellent plant deserves. We are grateful for the unwavering commitment of the men and women of Mt. Holly, who have operated the plant efficiently during these uncertain times; we are looking forward to supporting them as they rebuild the smelter and broaden the market for its high quality billet and other products.

We would not have the opportunity to reinvest in Mt. Holly without the continuing effectiveness of the Section 232 tariff. The Biden administration has demonstrated its recognition of the importance of this program through its early statements and actions; it is clear the administration shares our view that workers in U.S. manufacturing industries must have well-paying jobs on which they can depend for the long-term. We look forward to working with President Biden and his administration to uphold the meaningful positive impact of the Section 232 program.

The trade remedy has also reinforced our ability to continue to invest in the development of Hawesville and Sebree. Hawesville was brought successfully to 80 percent of capacity and maintained at that level for the majority of the year. Sebree continues to perform well, and we remain committed to invest to further the plant's ability to respond to our customers' requirements for quality value-added sustainable products.

Grundartangi has advanced its program of capacity growth, modernization and product innovation. This world-class plant, with its Aluminium Stewardship Institute performance certification, successfully created and launched Century's first low-carbon product, Natur-AlTM. We finalized a long-term agreement with a high quality OEM, and are in discussions with several other potential customers. We are excited about further developing Natur-AlTM and are actively working on a variety of sustainability initiatives across the company. We continue active investigation of greenfield renewable power sources for the Kentucky smelters, and are making good progress in that regard. We are confident that these types of opportunities will become more actionable for significant users of electric power, and are excited about the prospect of playing a leadership role in the U.S. in this critical effort.

Conditions in our industry have strengthened during 2021, and the opportunities for which we have invested are presenting themselves; we intend to capitalize on this environment. At the same time, your Board and management remain mindful of the volatile market in which we compete, and will continue to guide Century with a blend of opportunism and careful risk mitigation.

On behalf of the Board of Directors, we would like to thank our dedicated employees and the customers, suppliers, shareholders and other stakeholders who have contributed to Century's progress.

Sincerely,

Andrew Michelmore	Michael Bless
Chairman of the Board	President and Chief Executive Officer
April 28, 2021

PERFORMANCE

The following line graph compares Century Aluminum Company's cumulative total return to stockholders with the cumulative total return of the S&P 500® Index and the Dow Jones U.S. Aluminum Index during the period from December 31, 2015 through December 31, 2020. These comparisons assume the investment of $100 on December 31, 2015 and the reinvestment of dividends.

					Comparison of Cumulative Total Return to
					Stockholders December 31, 2015 through December
											31, 2020
					12/31/15	12/31/16	12/31/17	12/31/18	12/31/19	12/31/20
Century Aluminum Company	$100	$194				$444	$165	$170	$250
Dow Jones U.S. Aluminum	100	111				212	105	85	97
S&P 500® Index			100	112				136	130	171	203
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12/31/2015	12/31/2016	12/31/2017		12/31/2018	12/31/2019	12/31/2020
				Century Aluminum Company					S&P 500 Index		Dow Jones U.S. Aluminum Index

ASSUMES $100 INVESTED ON 12/31/2015 ASSUMES DVIDEND REINVESTMENT FISCAL YEAR ENDING DEC. 31,2020

CORPORATE INFORMATION

Corporate Headquarters

Century Aluminum Company

One South Wacker Drive,

Suite 1000 Chicago, IL 60606

Inquiries

Interested parties may contact the company at the address above or the phone number indicated below:

1-312-696-3101

Documents Available

Company documents, including the Form 10-K (filed with the Securities and Exchange Commission) and the company's Code of Ethics are available without charge upon request.

Write or contact our corporate secretary at the address or telephone number above.

Electronic versions of these documents are available on the company's website www.centuryaluminum.com.

Stock Transfer Agent

Computershare Trust Company, N.A.

462 South 4th Street, Suite 1600

Louisville, KY 40202

Telephone (Toll Free): 800-962-4284

International (Toll): [phone]

Independent Registered Public Accounting Firm

Deloitte & Touche LLP

111 South Wacker Drive

Suite 1800

Chicago, IL 60606

Stock Trading Information

Century Aluminum common stock is traded on NASDAQ. The ticker symbol is CENX.

2020	High	Low
First Quarter	$ 8.02	$ 3.15
Second Quarter	$ 7.87	$ 3.04
Third Quarter	$ 10.83	$ 6.81
Fourth Quarter	$ 12.09	$ 6.58

Forward-Looking Statements

This report contains forward-looking statements and actual results could be materially different. Various factors that could cause actual results to differ are described in the "Risk Factors" section and throughout Century's 2020 Form 10-K.

BR156431-0421-LTRSHR