Filed Pursuant to Rule 424(b)(3)

Registration No. 333-266136

PROSPECTUS SUPPLEMENT NO. 10

(To the Prospectus dated September 21, 2022)

Up to 10,916,647 Ordinary Shares Issuable Upon Exercise of Warrants

Up to 219,616,200 Ordinary Shares Offered by Selling Securityholders

Up to 4,666,667 Warrants to purchase Ordinary Shares offered by the Sponsor

This prospectus supplement supplements the prospectus, dated September 21, 2022 (the “Prospectus”), which forms a part of our registration statement on Form F-1 (No. 333-266136). This prospectus supplement is being filed to update and supplement the information in the Prospectus with the information contained in our Report on Form 6-K filed with the Securities and Exchange Commission (the “SEC”) on January 6, 2023 (the “Report”). Accordingly, we have attached the Report to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the issuance by us of 10,916,647 Ordinary Shares consisting of (i) 6,249,980 of our ordinary shares, $0.01 nominal value, (“Ordinary Shares”) that may be issued upon exercise of warrants to purchase Ordinary Shares at an exercise price of $11.50 (the “Public Warrants”), which were originally issued in the initial public offering of Oaktree Acquisition Corp. II (“OACB”) at a price of $10.00 per unit, with each unit consisting of one OACB Class A Ordinary Share (as defined in the Prospectus) and one-fourth of a Public Warrant, and (ii) 4,666,667 Ordinary Shares that may be issued upon exercise of warrants issued to Oaktree Acquisition Holdings II, L.P. (the “Sponsor”), and its transferees to purchase Ordinary Shares at an exercise price of $11.50 (the “Private Placement Warrants”). We refer to the Public Warrants and the Private Placement Warrants together as the “Warrants.”

The Prospectus and this prospectus supplement also relate to the offer and sale from time to time by the selling securityholders named in the Prospectus (collectively, the “Selling Securityholders”), or their permitted transferees, of up to (i) 17,493,000 Ordinary Shares subscribed for by the Selling Securityholders, for a subscription price of $10.00 per share, in the context of the PIPE Financing (as defined in the Prospectus), (ii) 6,250,000 Ordinary Shares issued to the Sponsor in exchange for OACB’s Class B Ordinary Shares, par value $0.0001 (which were purchased by the Sponsor for $25,000 or approximately $0.004 per share) in connection with the Business Combination (as defined in the Prospectus), (iii) 4,666,667 Ordinary Shares issuable upon exercise of Private Placement Warrants, (iv) 186,206,553 Ordinary Shares issued to former shareholders of Alvotech Holdings S.A. (“Alvotech Holdings”) in exchange for their Alvotech Holdings Ordinary Shares (as defined in the Prospectus) in connection with the Business Combination (subject to vesting and lockups) at an equity consideration value of $10.00 per share, (v) 5,000,000 Ordinary Shares subscribed for by Alvogen Lux Holdings S.à.r.l. and Aztiq Pharma Partners S.à.r.l., for a subscription price of $10.00 per share, in the context of the Alvogen-Aztiq Loan Advance Conversion (as defined in the Prospectus), and (vi) 4,666,667 Private Placement Warrants, which were purchased by the Sponsor at a price of $1.50 per warrant.

The Ordinary Shares and Warrants are listed on The Nasdaq Stock Market LLC (“Nasdaq”) under the symbols “ALVO” and “ALVOW,” respectively. On January 5, 2023, the closing price of the Ordinary Shares on Nasdaq was $10.05. The Ordinary Shares are also listed on the Nasdaq First North Growth Market (“Nasdaq First North”) under the symbol “ALVO.”

This prospectus supplement should be read in conjunction with the Prospectus, including any amendments or supplements thereto, which is to be delivered with this prospectus supplement. This prospectus supplement is qualified by reference to the Prospectus, including any amendments or supplements thereto, except to the extent that the information in this prospectus supplement updates and supersedes the information contained therein.

This prospectus supplement is not complete without, and may not be delivered or utilized except in connection with, the Prospectus, including any amendments or supplements thereto.

We are a “foreign private issuer” under applicable SEC rules and an “emerging growth company” as that term is defined in the Jumpstart Our Business Startups Act of 2012 and are eligible for reduced public company disclosure requirements.

You should read the Prospectus and any prospectus supplement or amendment carefully before you invest in our securities. Investing in our securities involves risks. See “Risk Factors” beginning on page 11 of the Prospectus and under similar headings in any amendments or supplements to the Prospectus.

Neither the SEC nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement or the Prospectus. Any representation to the contrary is a criminal offense.

The date of this Prospectus Supplement No. 10 is January 6, 2023.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the Month of January 2023

Commission File Number: 001-41421

Alvotech

(Translation of registrant’s name into English)

9, Rue de Bitbourg,

L-1273 Luxembourg,

Grand Duchy of Luxembourg

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

☒  Form 20-F                ☐  Form 40-F

INFORMATION CONTAINED IN THIS REPORT ON FORM 6-K

Press Release

On January 6, 2023, Alvotech announced that the U.S. Food and Drug Administration (FDA) has accepted for review a Biologics License Application (BLA) for AVT04, Alvotech’s proposed biosimilar to Stelara® (ustekinumab), which is prescribed to treat a variety of inflammatory conditions. Alvotech anticipates that the FDA’s review will be completed in October 2023. A copy of the announcement is furnished as Exhibit 99.1 to this Report of Form 6-K.

Forward Looking Statements

Certain statements in this communication may be considered “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements generally relate to future events and may include, for example, Alvotech’s expectations regarding regulatory review and interactions, the timing of the facility inspection by the FDA, satisfactory responses to the FDA’s inspection findings and resolution of deficiencies conveyed following the inspection of Alvotech’s manufacturing site, the potential approval and commercial launch of its product candidates, the timing of the announcement of clinical study results, regulatory approvals and market launches, the estimated size of the total addressable market of Alvotech’s pipeline products, competitive advantages, business prospects and opportunities including pipeline product development, future plans and intentions, results, level of activities, performance, goals or achievements or other future events. In some cases, you can identify forward-looking statements by terminology such as “may”, “should”, “expect”, “intend”, “will”, “estimate”, “anticipate”, “believe”, “predict”, “potential”, “aim” or “continue”, or the negatives of these terms or variations of them or similar terminology. Such forward-looking statements are subject to risks, uncertainties, and other factors which could cause actual results to differ materially from those expressed or implied by such forward-looking statements. These forward-looking statements are based upon estimates and assumptions that, while considered reasonable by Alvotech and its management, are inherently uncertain and are inherently subject to risks, variability, and contingencies, many of which are beyond Alvotech’s control. Factors that may cause actual results to differ materially from current expectations include, but are not limited to: (1) the outcome of any legal proceedings that may be instituted against Alvotech or others following the business combination between Alvotech Holdings S.A., Oaktree Acquisition Corp. II and Alvotech; (2) the ability to maintain stock exchange listing standards; (3) changes in applicable laws or regulations; (4) the possibility that Alvotech may be adversely affected by other economic, business, and/or competitive factors; (5) Alvotech’s estimates of expenses and profitability; (6) Alvotech’s ability to develop, manufacture and commercialize the products and product candidates in its pipeline; (7) the ability of Alvotech or its partners to respond to inspection findings and resolve deficiencies to the satisfaction of the regulators; (8) actions of regulatory authorities, which may affect the initiation, timing and progress of clinical studies or future regulatory approvals or marketing authorizations; (9) the ability of Alvotech or its partners to enroll and retain patients in clinical studies; (10) the ability of Alvotech or its partners to gain approval from regulators for planned clinical studies, study plans or sites; (11) the ability of Alvotech’s partners to conduct, supervise and monitor existing and potential future clinical studies, which may impact development timelines and plans; (12) Alvotech’s ability to obtain and maintain regulatory approval or authorizations of its products, including the timing or likelihood of expansion into additional markets or geographies; (13) the success of Alvotech’s current and future collaborations, joint ventures, partnerships or licensing arrangements; (14) Alvotech’s ability, and that of its commercial partners, to execute their commercialization strategy for approved products; (15) Alvotech’s ability to manufacture sufficient commercial supply of its approved products; (16) the outcome of ongoing and future litigation regarding Alvotech’s products and product candidates; (17) the potential impact of the ongoing COVID-19 pandemic on the FDA’s review timelines, including its ability to complete timely inspection of manufacturing sites; (18) the impact of worsening macroeconomic conditions, including rising inflation and interest rates and general market conditions, war in Ukraine and global geopolitical tension, and the ongoing and evolving COVID-19 pandemic on the Company’s business, financial position, strategy and anticipated milestones; and (19) other risks and uncertainties set forth in the sections entitled “Risk Factors” and “Cautionary Note Regarding Forward-Looking Statements” in documents that Alvotech may from time to time file or furnish with the SEC. There may be additional risks that Alvotech does not presently know or that Alvotech currently believes are immaterial that could also cause actual results to differ from those contained in the forward-looking statements. Nothing in this communication should be regarded as a representation by any person that the forward-looking

statements set forth herein will be achieved or that any of the contemplated results of such forward-looking statements will be achieved. You should not place undue reliance on forward-looking statements, which speak only as of the date they are made. Alvotech does not undertake any duty to update these forward-looking statements or to inform the recipient of any matters of which any of them becomes aware of which may affect any matter referred to in this communication. Alvotech disclaims any and all liability for any loss or damage (whether foreseeable or not) suffered or incurred by any person or entity as a result of anything contained or omitted from this communication and such liability is expressly disclaimed. The recipient agrees that it shall not seek to sue or otherwise hold Alvotech or any of its directors, officers, employees, affiliates, agents, advisors, or representatives liable in any respect for the provision of this communication, the information contained in this communication, or the omission of any information from this communication.

INCORPORATION BY REFERENCE

The Company hereby incorporates by reference the information contained in the body of this Report on Form 6-K into the Company’s registration statements on Form S-8 (File No. 333-266881) of Alvotech and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

Exhibit 99.1 to this Report is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act.

EXHIBIT INDEX

SIGNATURES

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.

Exhibit 99.1

Alvotech and Teva Announce Acceptance of U.S. Biologics License

Application for AVT04, a Proposed Biosimilar to Stelara^® (ustekinumab)

REYKJAVIK, ICELAND & PARSIPPANY, NJ (January 6, 2023) — Alvotech (NASDAQ: ALVO), a global biotech company specializing in the development and manufacture of biosimilar medicines for patients worldwide, and Teva Pharmaceuticals, a U.S. affiliate of Teva Pharmaceutical Industries Ltd. (NYSE and TASE: TEVA), today announced that the U.S. Food and Drug Administration (FDA) has accepted for review a Biologics License Application (BLA) for AVT04, Alvotech’s proposed biosimilar to Stelara^® (ustekinumab), which is prescribed to treat a variety of inflammatory conditions. The companies anticipate that the FDA’s review will be completed in the second half of 2023.

“The progress of AVT04 helps to validate the end-to-end biosimilars development and manufacturing platform that we have built at Alvotech,” said Joseph McClellan, Chief Scientific Officer of Alvotech. “Our approach is multi-product, and we look forward to broadening our portfolio as we continue to focus on expanding access to affordable biologic medicines.”

“We are pleased to be one step closer to making AVT04 available to patients and providers as a biosimilar treatment option to Stelara^® for indicated inflammatory conditions,” said Christine Baeder, SVP, Chief Operating Officer US Generics, Teva. “Teva continues to remain focused on our commitment to lower healthcare costs and expand the availability and access of biosimilars.”

In August 2020, Alvotech and Teva announced a strategic partnership for the exclusive commercialization in the U.S. of five of Alvotech’s biosimilar product candidates. In May 2022, Alvotech announced that a confirmatory clinical, safety and efficacy study for AVT04 had met its primary endpoint, in demonstrating therapeutic equivalence between Alvotech’s biosimilar candidate and the reference product in patients with moderate to severe chronic plaque-type psoriasis. Earlier in May 2022, Alvotech also announced positive top-line results from a pharmacokinetic (PK) similarity study for AVT04.

About AVT04 (ustekinumab)

AVT04 is a monoclonal antibody and a biosimilar candidate to Stelara^® (ustekinumab). Ustekinumab binds to two cytokines, IL-12 and IL-23, that are involved in inflammatory and immune responses [1]. AVT04 is an investigational product and has not received regulatory approval in any country. Biosimilarity has not been established by regulatory authorities and is not claimed.

* Stelara^® is a registered trademark of Johnson & Johnson

[1] https://www.janssenlabels.com/package-insert/product-monograph/prescribing-information/STELARA-pi.pdf

About Alvotech

Alvotech is a biotech company, founded by Robert Wessman, focused solely on the development and manufacture of biosimilar medicines for patients worldwide. Alvotech seeks to be a global leader in the biosimilar space by delivering high quality, cost-effective products, and services, enabled by a fully integrated approach and broad in-house capabilities. Alvotech’s current pipeline contains eight biosimilar candidates aimed at treating autoimmune disorders, eye disorders, osteoporosis, respiratory disease, and cancer. Alvotech has formed a network of strategic commercial partnerships to provide global reach and leverage local expertise in markets that include the United States, Europe, Japan, China, and other Asian countries and large parts of South America, Africa and the Middle East. Alvotech’s commercial partners include Teva Pharmaceuticals, a US affiliate of Teva Pharmaceutical Industries Ltd. (US), STADA Arzneimittel AG (EU), Fuji Pharma Co., Ltd (Japan), Cipla/Cipla Gulf/Cipla Med Pro (Australia, New Zealand, South Africa/Africa), JAMP Pharma Corporation (Canada), Yangtze River Pharmaceutical (Group) Co., Ltd. (China), DKSH (Taiwan, Hong Kong, Cambodia, Malaysia, Singapore, Indonesia, India, Bangladesh and Pakistan), YAS Holding LLC (Middle East and North Africa), Abdi Ibrahim (Turkey), Kamada Ltd. (Israel), Mega Labs, Stein, Libbs, Tuteur and Saval (Latin America) and Lotus Pharmaceuticals Co., Ltd. (Thailand, Vietnam, Philippines, and South Korea). Each commercial partnership covers a unique set of product(s) and territories. Except as specifically set forth therein, Alvotech disclaims responsibility for the content of periodic filings, disclosures and other reports made available by its partners. For more information, please visit www.alvotech.com. None of the information on the Alvotech website shall be deemed part of this press release.

About Teva

Teva Pharmaceutical Industries Ltd. (NYSE and TASE: TEVA) has been developing and producing medicines to improve people’s lives for more than a century. We are a global leader in generic and specialty medicines with a portfolio consisting of over 3,500 products in nearly every therapeutic area. Around 200 million people around the world take a Teva medicine every day and are served by one of the largest and most complex supply chains in the pharmaceutical industry. Along with our established presence in generics, we have significant innovative research and operations supporting our growing portfolio of specialty and biopharmaceutical products. Learn more at www.tevapharm.com.

Forward Looking Statements (Alvotech)

Certain statements in this communication may be considered “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements generally relate to future events and may include, for example, Alvotech’s expectations regarding regulatory review and interactions, the timing and results of the facility inspection by the FDA, satisfactory responses to the FDA’s inspection findings and resolution of deficiencies conveyed following the inspection of Alvotech’s manufacturing site, the potential approval and commercial launch of its product candidates, the timing of the announcement of clinical study results, regulatory approvals and market launches, the estimated size of the total addressable market of Alvotech’s pipeline products, competitive advantages, business prospects and opportunities including pipeline product development, future plans and intentions, results, level of activities, performance, goals or achievements or other future events. In some cases, you can identify forward-looking statements by terminology such as “may”, “should”, “expect”, “intend”, “will”, “estimate”, “anticipate”, “believe”, “predict”, “potential”, “aim” or “continue”, or the negatives of these terms or variations of them or

similar terminology. Such forward-looking statements are subject to risks, uncertainties, and other factors which could cause actual results to differ materially from those expressed or implied by such forward-looking statements. These forward-looking statements are based upon estimates and assumptions that, while considered reasonable by Alvotech and its management, are inherently uncertain and are inherently subject to risks, variability, and contingencies, many of which are beyond Alvotech’s control. Factors that may cause actual results to differ materially from current expectations include, but are not limited to: (1) the outcome of any legal proceedings that may be instituted against Alvotech or others following the business combination between Alvotech Holdings S.A., Oaktree Acquisition Corp. II and Alvotech; (2) the ability to maintain stock exchange listing standards; (3) changes in applicable laws or regulations; (4) the possibility that Alvotech may be adversely affected by other economic, business, and/or competitive factors; (5) Alvotech’s estimates of expenses and profitability; (6) Alvotech’s ability to develop, manufacture and commercialize the products and product candidates in its pipeline; (7) the ability of Alvotech or its partners to respond to inspection findings and resolve deficiencies to the satisfaction of the regulators; (8) actions of regulatory authorities, which may affect the initiation, timing and progress of clinical studies or future regulatory approvals or marketing authorizations; (9) the ability of Alvotech or its partners to enroll and retain patients in clinical studies; (10) the ability of Alvotech or its partners to gain approval from regulators for planned clinical studies, study plans or sites; (11) the ability of Alvotech’s partners to conduct, supervise and monitor existing and potential future clinical studies, which may impact development timelines and plans; (12) Alvotech’s ability to obtain and maintain regulatory approval or authorizations of its products, including the timing or likelihood of expansion into additional markets or geographies; (13) the success of Alvotech’s current and future collaborations, joint ventures, partnerships or licensing arrangements; (14) Alvotech’s ability, and that of its commercial partners, to execute their commercialization strategy for approved products; (15) Alvotech’s ability to manufacture sufficient commercial supply of its approved products; (16) the outcome of ongoing and future litigation regarding Alvotech’s products and product candidates; (17) the potential impact of the ongoing COVID-19 pandemic on the FDA’s review timelines, including its ability to complete timely inspection of manufacturing sites; (18) the impact of worsening macroeconomic conditions, including rising inflation and interest rates and general market conditions, war in Ukraine and global geopolitical tension, and the ongoing and evolving COVID-19 pandemic on the Company’s business, financial position, strategy and anticipated milestones; and (19) other risks and uncertainties set forth in the sections entitled “Risk Factors” and “Cautionary Note Regarding Forward-Looking Statements” in documents that Alvotech may from time to time file or furnish with the SEC. There may be additional risks that Alvotech does not presently know or that Alvotech currently believes are immaterial that could also cause actual results to differ from those contained in the forward-looking statements. Nothing in this communication should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that any of the contemplated results of such forward-looking statements will be achieved. You should not place undue reliance on forward-looking statements, which speak only as of the date they are made. Alvotech does not undertake any duty to update these forward-looking statements or to inform the recipient of any matters of which any of them becomes aware of which may affect any matter referred to in this communication. Alvotech disclaims any and all liability for any loss or damage (whether foreseeable or not) suffered or incurred by any person or entity as a result of anything contained or omitted from this communication and such liability is expressly disclaimed. The recipient agrees that it shall not seek to sue or otherwise hold Alvotech or any of its directors, officers, employees, affiliates, agents, advisors, or representatives liable in any respect for the provision of this communication, the information contained in this communication, or the omission of any information from this communication.

Cautionary Note Regarding Forward-Looking Statements (Teva)

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, which are based on management’s current beliefs and expectations and are subject to substantial risks and uncertainties, both known and unknown, that could cause our future results, performance or achievements to differ significantly from that expressed or implied by such forward-looking statements. You can identify these forward-looking statements by the use of words such as “should,” “expect,” “anticipate,” “estimate,” “target,” “may,” “project,” “guidance,” “intend,” “plan,” “believe” and other words and terms of similar meaning and expression in connection with any discussion of future operating or financial performance. Important factors that could cause or contribute to such differences include risks relating to our ability to develop our biosimilar products pipeline; our ability to successfully compete in the marketplace, including our ability to develop and commercialize biopharmaceutical products, competition for our innovative medicines, including AUSTEDO^®, AJOVY^® and COPAXONE^®; our ability to achieve expected results from investments in our product pipeline, our ability to develop and commercialize additional pharmaceutical products, and the effectiveness of our patents and other measures to protect our intellectual property rights; our substantial indebtedness; our business and operations in general; costs and delays resulting from the extensive pharmaceutical regulation to which we are subject to, or delays in governmental processing time due to travel and work restrictions caused by the COVID-19 pandemic; compliance, regulatory and litigation matters, including failure to comply with complex legal and regulatory environments; other financial and economic risks; and other factors discussed in our Quarterly Report on Form 10-Q for the third quarter of 2022 and in our Annual Report on Form 10-K for the year ended December 31, 2021, including in the section captioned “Risk Factors.” Forward-looking statements speak only as of the date on which they are made, and we assume no obligation to update or revise any forward-looking statements or other information contained herein, whether as a result of new information, future events or otherwise. You are cautioned not to put undue reliance on these forward-looking statements.

CONTACTS

Alvotech Investor Relations and Global Communications

Benedikt Stefansson

alvotech.ir[at]alvotech.com

Teva Investor Relations

Ran Meir

Ran.Meir@tevapharm.com

Yael Ashman

Yael.Ashman@teva.co.il

Teva PR Contacts

Doris Yiu

Doris.Yiu@tevapharm.com

Yonatan Beker

Yonatan.Beker@tevapharm.com