Stealth BioTherapeutics (MITO) 424B5 Prospectus supplement for primary offering

Filed pursuant to Rule 424(b)(5)
Registration Statement No. 333-237542

Prospectus Supplement No. 4

(To Prospectus dated April 10, 2020)

2,339,000 American Depositary Shares

Representing 28,068,000 Ordinary Shares

We are offering 2,339,000 American Depositary Shares (“ADS”), each representing 12 ordinary shares, each with a nominal or par value of $0.0003 per share (“Ordinary Shares”), to certain institutional investors pursuant to this prospectus supplement and the accompanying prospectus.

Our ADSs are listed on The Nasdaq Global Market under the symbol “MITO.” On February 9, 2021, the last reported sale price of our ADSs reported on the Nasdaq Global Market was $2.42 per ADS.

As of February 9, 2021, the aggregate market value of our outstanding Ordinary Shares held by non-affiliates was $23,634,276.60, which was calculated based on the 9,766,230 ADSs issued and outstanding held by non-affiliates, each representing 12 Ordinary Shares, and a price per ADS of $2.42, which was the closing price of our ADSs on February 9, 2021. Pursuant to General Instruction I.B.5 of Form F-3, in no event will we sell, pursuant to the registration statement of which this prospectus supplement forms a part, securities in a public primary offering with a value exceeding one-third of the aggregate market value of our common stock held by non-affiliates in any 12-month period, so long as the aggregate market value of our outstanding common stock held by non-affiliates remains below $75 million. During the 12 calendar months prior to and including the date of this prospectus supplement, we have sold securities pursuant to General Instruction I.B.5 of Form F-3 in the aggregate amount of $3,200,001.75, as calculated under such General Instruction. Following the sale of Shares in this offering, we will have sold securities with an aggregate market value of $7,878,001.75 pursuant to General Instruction I.B.5 of Form F-3 during the 12-month calendar period that ends on and includes the date hereof.

We are an “emerging growth company” as defined in Section 2(a) of the Securities Act of 1933, as amended. As such, we have elected to rely on certain reduced public company disclosure requirements. See “Prospectus Supplement Summary—Implications of Being an Emerging Growth Company.”

Investing in our securities involves significant risks. See “Risk Factors” beginning on page S-11 of this prospectus supplement and in our filings with the Securities and Exchange Commission that are incorporated by reference in this prospectus supplement to read about factors you should consider before buying our securities.

We have engaged H.C. Wainwright & Co., LLC, or the placement agent, to act as our exclusive placement agent in connection with this offering. The placement agent has agreed to use its reasonable best efforts to arrange for the sale of the securities offered by this prospectus supplement and the accompanying prospectus. The placement agent has no obligation to buy any securities from us or to arrange for the purchase or sale of any specific number or dollar amount of our securities. We have agreed to pay the placement agent the placement agent fees set forth in the table below. There is no arrangement for funds to be received in escrow, trust or similar arrangement. There is no minimum offering requirement. The placement agent may engage one or more sub-placement agents or selected dealers in connection with the offering. See “Plan of Distribution” beginning on page S-26 of this prospectus supplement for more information regarding this arrangement.

	Per ADS		Total
Offering price	$	2.00	$	4,678,000.00
Placement agent fees(1)	$	0.12	$	280,680.00
Proceeds, before expenses, to us	$	1.88	$	4,397,320.00

(1) In addition, we have agreed to pay to the placement agent a management fee equal to 1.0% of the gross proceeds in this offering and a non-accountable expense allowance of $35,000 and to reimburse the placement agent for certain offering-related expenses. See “Plan of Distribution” on page S-26 for additional information.

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

Delivery of the ADSs offered hereby is expected to occur on or about February 11, 2021, subject to the satisfaction of certain closing conditions.

H.C. Wainwright & Co.

The date of this prospectus supplement is February 9, 2021

TABLE OF CONTENTS

Prospectus Supplement

ABOUT THIS PROSPECTUS SUPPLEMENT	S-1
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	S-2
PROSPECTUS SUPPLEMENT SUMMARY	S-4
THE OFFERING	S-9
RISK FACTORS	S-11
USE OF PROCEEDS	S-15
DIVIDEND POLICY	S-16
DILUTION	S-17
DESCRIPTION OF THE SECURITIES WE ARE OFFERING	S-19
TAXATION	S-20
PLAN OF DISTRIBUTION	S-26
LEGAL MATTERS	S-28
EXPERTS	S-28
WHERE YOU CAN FIND MORE INFORMATION	S-29
INCORPORATION BY REFERENCE	S-30

Prospectus

ABOUT THIS PROSPECTUS	1
RISK FACTORS	2
WHERE YOU CAN FIND MORE INFORMATION	3
INCORPORATION BY REFERENCE	3
FORWARD-LOOKING STATEMENTS	4
THE COMPANY	5
CAPITALIZATION AND INDEBTEDNESS	6
USE OF PROCEEDS	7
DESCRIPTION OF SHARE CAPITAL AND ARTICLES OF ASSOCIATION	8
DESCRIPTION OF AMERICAN DEPOSITARY SHARES	22
DESCRIPTION OF UNITS	33
DESCRIPTION OF WARRANTS	33
FORMS OF SECURITIES	34
TAXATION	36
PLAN OF DISTRIBUTION	36
LEGAL MATTERS	39
EXPERTS	39
EXPENSES	39
ENFORCEMENT OF CIVIL LIABILITIES	40

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ABOUT THIS PROSPECTUS SUPPLEMENT

This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference herein. The second part, the accompanying prospectus, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement and the information contained in the accompanying prospectus or any document incorporated by reference therein filed prior to the date of this prospectus supplement, you should rely on the information in this prospectus supplement; provided that if any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in the accompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

We have not and the placement agent has not authorized anyone to provide any information other than that contained or incorporated by reference in this prospectus supplement, in the accompanying prospectus or in any free writing prospectus prepared by or on our behalf or to which we or the placement agent has referred you. We and the placement agent take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you.

This prospectus supplement and the accompanying prospectus do not constitute an offer to sell, or a solicitation of an offer to purchase, the securities offered by this prospectus supplement and the accompanying prospectus in any jurisdiction to or from any person to whom or from whom it is unlawful to make such offer or solicitation of an offer in such jurisdiction. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein and in any free writing prospectus that we have authorized for use in connection with this offering is accurate only as of the date of those respective documents. It is important for you to read and consider all information contained in this prospectus supplement and in the accompanying prospectus, including the documents incorporated by reference herein and therein, in making your investment decision. You should also read and consider the information in the documents to which we have referred you in the sections entitled “Where You Can Find More Information” and “Incorporation by Reference” in this prospectus supplement and in the accompanying prospectus.

Other than in the United States, no action has been taken by us or the placement agent that would permit a public offering of the securities offered by this prospectus supplement in any jurisdiction where action for that purpose is required. The securities offered by this prospectus supplement may not be offered or sold, directly or indirectly, nor may this prospectus supplement or any other offering material or advertisements in connection with the offer, issue and sale of any such securities be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus supplement comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus supplement. This prospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus in any jurisdiction in which such an offer or a solicitation is unlawful.

Unless the context otherwise indicates, references in this prospectus supplement to “Stealth BioTherapeutics Corp,” “Stealth,” “the Company,” “we,” “our” and “us” refer, collectively, to Stealth BioTherapeutics Corp and its consolidated subsidiaries, or any one or more of them as the context may require.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein contain forward-looking statements that involve substantial risks and uncertainties. All statements regarding our strategy, future operations, future financial position, future revenue, projected costs, prospects, plans, objectives of management and expected market growth other than statements of historical facts contained in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein are forward-looking statements. The words “anticipate,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “seek,” “should,” “target,” “will,” “would” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements include, but are not limited to, statements about:

• our plans to develop and commercialize elamipretide, SBT-272, SBT-550 and our other product candidates, and to identify additional product candidates;

• ongoing and planned clinical trials and preclinical studies for our product candidates, including the timing of initiation of these trials and studies and the timing of the anticipated results;

• our plans to submit a new drug application, or NDA, for Barth Syndrome;

• our plans to possibly enter into collaborations for the development of product candidates and the potential benefits of any collaboration;

• the timing of anticipated regulatory filings, meetings with regulatory agencies or regulatory approvals and plans and expectations for expedited regulatory review for our product candidates;

• the potential advantages and clinical utility of our product candidates;

• our commercialization, marketing and manufacturing capabilities and strategy;

• our intellectual property position and strategy;

• our estimates regarding the potential market opportunity for our product candidates;

• our expected use of proceeds from this offering; and

• our estimates regarding expenses, future revenue, capital requirements, sufficiency of our current cash and cash equivalent and our need for and ability to obtain additional funding.

These forward-looking statements involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements in this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. We have included important factors in the cautionary statements included in this prospectus supplement, particularly in the “Risk Factors” section, that could cause actual results or events to differ materially from the forward-looking statements that we make. Except as context otherwise requires, our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments that we may make.

You should read this prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein completely and with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements contained in this prospectus supplement are made as of the date of this prospectus supplement and we do not assume any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.

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This prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein includes statistical and other industry and market data, which we obtained from our own internal estimates and research, as well as from industry and general publications and research, surveys and studies conducted by third parties. Industry publications, studies and surveys generally state that they have been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. While we believe that each of these studies, reports and publications is reliable, we have not independently verified market and industry data from third-party sources. While we believe our internal company research is reliable and the market definitions are appropriate, neither such research nor these definitions have been verified by any independent source.

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PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights selected information contained elsewhere in this prospectus supplement and the accompanying prospectus and in the documents we incorporate by reference herein and therein. This summary does not contain all of the information you should consider before investing in our ADSs. You should read this entire prospectus supplement and the accompanying prospectus carefully, especially the risks of investing in our ADSs discussed under “Risk Factors” in this prospectus supplement and under “Risk Factors” in our Annual Report on Form 20-F for the fiscal year ended December 31, 2019, along with our consolidated financial statements and notes to those consolidated financial statements and the other information incorporated by reference in this prospectus supplement and the accompanying prospectus, before deciding to invest in our ADSs.

Overview of Stealth BioTherapeutics Corp

We are a clinical-stage biotechnology company focused on the discovery, development and commercialization of novel therapies for diseases involving mitochondrial dysfunction. Mitochondria, found in nearly every cell in the body, are the body’s main source of energy production and are critical for normal organ function. Dysfunctional mitochondria characterize a number of rare genetic diseases and many common age-related diseases, leading to devastating cardiac, ophthalmic and neurological symptoms. We believe our product candidates have significant potential to treat the cardiac, ophthalmic and neurological symptoms of both rare genetic and common age-related mitochondrial diseases. Our mission is to be the leader in mitochondrial medicine, and we have assembled a highly experienced management team, board of directors and group of scientific advisors to help us achieve this mission.

Our first clinical product candidate, elamipretide, is a small peptide that targets and binds reversibly to cardiolipin, an essential structural element of mitochondria, stabilizing the inner mitochondrial membrane under conditions of oxidative stress. This novel mechanism of action has shown potential clinical benefit in both rare genetic and common age-related cardiac and ophthalmic diseases entailing mitochondrial dysfunction. Elamipretide has been generally well tolerated in clinical trials with over 1,000 subjects exposed to it systemically to date. We have exclusive worldwide rights to elamipretide, which we licensed from Cornell and Institut de recherches cliniques de Montréal in 2006.

We are studying elamipretide in the following ophthalmic and cardiac disease indications:

• Barth Syndrome, or Barth, an inherited cardiomyopathic disease, for which we have conducted a Phase 3 retrospective natural history-controlled trial and a Phase 2/3 clinical trial in the United States; and

• Geographic atrophy, or GA, an advanced form of dry age-related macular degeneration, for which we have conducted a Phase 1 clinical trial in the United States and in March 2019 initiated a Phase 2b clinical trial in the United States.

Our Phase 2b trial for GA is now over 90% enrolled, with complete enrollment expected in the first quarter of 2021. We expect data from this trial in the first half of 2022.

We recently met with the Division of Cardiology and Nephrology at the U.S. Food and Drug Administration, or FDA, to discuss a potential new drug application, or NDA, submission for Barth. The FDA did not agree that the current data package is sufficient to support an NDA submission, and recommended that we collect additional controlled clinical data in this indication prior to an NDA submission. We also received a petition signed by over 4,250 members of the Barth community requesting us to submit our NDA on the basis of our existing data. We subsequently requested and have been granted a pre-NDA meeting and expect to submit our NDA following this meeting, in early 2021. We also plan to submit a protocol contemplating the withdrawal of the subjects remaining on open-label extension in our Phase 2/3 Barth trial and a protocol for a Phase 4 post-marketing

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withdrawal trial to assess whether the benefits of elamipretide are sustained after cessation of dosing. We hope to initiate the withdrawal study in early 2021.

We are evaluating the potential for additional clinical trials of elamipretide in the following cardiac, ophthalmic and mitochondrial disease indications:

• Duchenne cardiomyopathy, which is the heart muscle weakness associated with Duchenne’s muscular dystrophy, or DMD, which is phenotypically like the cardiomyopathy assessed in our Barth program and is the leading cause of early mortality in this disease;

• Friedreich’s ataxia, or FRDA, which is associated with both cardiomyopathy and progressive decline in visual function;

• Leber’s hereditary optic neuropathy, or LHON, an inherited disease of central blindness, for which we have conducted a Phase 2 clinical trial in the United States; and

• Mitochondrial replisome-related disorders, caused by mutations in nuclear genes that encode for proteins involved in mitochondrial DNA replication.

Subject to discussions with the FDA, continued planning efforts and financing plans, we hope to initiate a clinical development program for elamipretide in DMD patients with cardiomyopathy during the second half of 2021, focusing primarily on cardiac endpoints. We plan to support an investigator-initiated Phase 2a open-label clinical trial of elamipretide assessing both visual and cardiac endpoints in FRDA, which is anticipated to commence enrollment in early 2021, and we hope that results from this trial will help inform a pivotal trial design. We may initiate a Phase 3 global clinical trial for elamipretide in LHON, subject to ongoing formulation studies expected to read out in early 2022, continued planning efforts, and financing plans. We also hope to initiate a pivotal trial for elamipretide in patients with mitochondrial replisome-related disorders during the second half of 2021, subject to discussions with the FDA, continued planning efforts and financing plans; these subjects were among a subgroup of patients with nuclear DNA mutations in whom improvements were observed in our Phase 3 primary mitochondrial myopathy trial.

Our second clinical product candidate, SBT-272, is a novel peptidomimetic that has been shown to increase adenosine triphosphate production and decrease levels of reactive oxygen species in dysfunctional mitochondria in preclinical studies. In early experiments, SBT-272 demonstrated higher mitochondrial uptake, greater concentrations in the brain, and improved oral bioavailability relative to elamipretide. We are developing SBT-272 for rare neurological diseases involving mitochondrial dysfunction. Preliminary results from a Phase 1 clinical trial in healthy human volunteers completed during 2020 suggest that SBT-272 showed a favorable safety profile. We are evaluating drug exposure to inform formulation plans and may also explore subcutaneous dosing. We plan to commence long-term toxicology studies to support chronic dosing during 2021. We have also conducted and continue to conduct preclinical studies in neurological disease models to inform our decisions regarding our first Phase 2 indication.

We have discovered and own over 100 compounds, including SBT-272 and the SBT-550 family, that also target the mitochondria and form the basis of our broad proprietary pipeline of mitochondrial-targeted product candidates. We are evaluating compounds in the SBT-550 family for rare neurological indications. In addition, our internal discovery platform has generated a library of over 100 differentiated proprietary compounds which could have clinical benefit for diseases related to mitochondrial dysfunction and from which we plan to designate potential product candidates. We may also utilize certain of these compounds as part of our carrier platform, in which they could potentially serve as scaffolds to deliver other beneficial compounds to the mitochondria.

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Recent Developments

As of September 30, 2020, we had cash and cash equivalents of $19.9 million. In October 2020, we entered into a Development Funding Agreement with Morningside Ventures (I) Investment Limited, or MVIL, under which MVIL agreed to provide us funding to support our efforts to secure regulatory approval for elamipretide and to develop elamipretide for the treatment of Barth, GA, FRDA, Duchenne cardiomyopathy, replisome-related disorders and LHON. We received initial cash proceeds of $20.0 million pursuant to the Development Funding Agreement, and we may receive up to an additional $15.0 million upon the completion of certain near-term milestones. In November 2020, we entered into a Securities Purchase Agreement with certain institutional investors for a registered direct offering, or the 2020 Offering, of an aggregate of 2,844,446 ADSs at a public offering price of $1.125 per ADS for net proceeds of approximately $2.6 million.

Risks Associated with Our Business

Our business is subject to a number of risks of which you should be aware before making an investment decision. These risks are discussed more fully in the “Risk Factors” section of this prospectus supplement immediately following this prospectus supplement summary and in our Annual Report on Form 20-F for the fiscal year ended December 31, 2019. These risks include, but are not limited to, the following:

• We will need substantial additional funding. If we are unable to raise capital when needed, we would be forced to delay, reduce or eliminate our research and drug development programs or commercialization efforts. If we do raise additional capital, it may cause dilution to our shareholders.

• Based on our cash balances, recurring losses and our projected spending in 2021, and without giving effect to the proceeds of this offering or additional potential additional funding or milestones payments under the Development Funding Agreement, there is a substantial doubt about our ability to continue as a going concern.

• We have incurred significant losses since inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability. As of September 30, 2020, we had an accumulated deficit of $537.1 million.

• We depend heavily on the success of our clinical product candidates, and we cannot be certain that we will receive regulatory approval for any of our product candidates or if we will successfully commercialize any of our product candidates even if we receive such regulatory approval.

• Our approach to the discovery and development of product candidates that target mitochondria is unproven, and we do not know whether we will be able to develop any products of commercial value.

• If clinical trials of our product candidates fail to demonstrate safety and efficacy to the satisfaction of regulatory authorities or do not otherwise produce positive results, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our product candidates.

• We expect to depend on third parties for the development, marketing and/or commercialization of our product candidates in some cases. If those collaborations are not successful, we may not be able to capitalize on the market potential of our product candidates.

• We hold exclusive licenses from Cornell Research Foundation and the Institut de recherches cliniques de Montréal for our lead clinical-stage product candidate elamipretide. If these third parties terminate their agreements with us, our competitive position and our market share will be harmed. For example, our license agreement with Cornell requires us to commercialize a product by December 31, 2020, subject to specified exceptions for causes due to scientific and regulatory events that are common in drug development, and Cornell has the right to terminate the license if we do not comply. We believe that our noncompliance is subject to the named exceptions, and to date we have not received any notice of termination from Cornell.

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• MVIL has a controlling interest in us and is be able to control all matters submitted to our shareholders for approval that require an ordinary resolution or special resolution, as well as our management and affairs.

• As a foreign private issuer, we are exempt from a number of rules under the U.S. securities laws and Nasdaq Stock Market, or Nasdaq, and corporate governance rules and are permitted to file less information with the Securities and Exchange Commission, or the SEC, than U.S. companies. This may limit the information available to holders of the ADSs.

Our Corporate Information

We were incorporated in April 2006 under the name of Stealth Peptides International Inc as an exempted company incorporated with limited liability under the laws of the Cayman Islands, and we changed our name in June 2015 to Stealth BioTherapeutics Corp. Our registered office is located at c/o Intertrust Corporate Services (Cayman) Limited, 190 Elgin Avenue, George Town, Grand Cayman, KY1-9005 Cayman Islands. Our agent for service of process in the United States is Stealth BioTherapeutics Inc. (“Stealth Delaware”), and the executive offices of Stealth Delaware are located at 140 Kendrick Street, Needham, MA 02494, and the telephone number there is (617) 600-6888.

Our website address is www.stealthbt.com. The information contained on, or that can be accessed through, our website is not a part of this prospectus supplement or the accompanying prospectus. We have included our website address in this prospectus supplement and the accompanying prospectus solely as an inactive textual reference.

“Stealth BioTherapeutics,” the Stealth BioTherapeutics logo and our other trademarks or service marks appearing in this prospectus supplement are the property of Stealth BioTherapeutics or our subsidiaries.

Implications of Being an Emerging Growth Company

We qualify as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. An emerging growth company may take advantage of specified reduced reporting and other burdens that are otherwise applicable generally to public companies. These provisions include:

• an exemption from compliance with the auditor attestation requirement of Section 404 of the Sarbanes-Oxley Act of 2002 on the design and effectiveness of our internal controls over financial reporting;

• an exemption from compliance with any requirement that the Public Company Accounting Oversight Board may adopt regarding mandatory audit firm rotation or a supplement to the auditor’s report providing additional information about the audit and the financial statements;

• reduced disclosure about the company’s executive compensation arrangements; and

• exemptions from the requirements to obtain a non-binding advisory vote on executive compensation or a shareholder approval of any golden parachute arrangements.

We may take advantage of these provisions until December 31, 2024 or such earlier time that we are no longer an emerging growth company. We would cease to be an emerging growth company upon the earlier to occur of: the last day of the fiscal year in which we have more than $1.07 billion in annual revenues; the date we qualify as a “large accelerated filer,” with a non-affiliate public float in excess of $700 million; or the issuance by us of more than $1 billion of non-convertible debt over a three-year period. We may choose to take advantage of some, but not all, of the available benefits under the JOBS Act. We have taken advantage of some reduced reporting burdens in this prospectus supplement. Accordingly, the information contained herein may be different than the information you receive from other public companies in which you hold securities.

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In addition, the JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. This provision allows an emerging growth company to delay the adoption of some accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this exemption from new or revised accounting standards and, therefore, we will not be subject to the same new or revised accounting standards as other public companies.

Implications of Being a Foreign Private Issuer

Our status as a foreign private issuer also exempts us from compliance with certain laws and regulations of the SEC and certain regulations of Nasdaq. Consequently, we are not subject to all of the disclosure requirements applicable to companies organized within the United States. For example, we are exempt from certain rules under the Exchange Act that regulate disclosure obligations and procedural requirements related to the solicitation of proxies, consents or authorizations applicable to a security registered under the Exchange Act. In addition, our senior management and supervisory board members are exempt from the reporting and “short-swing” profit recovery provisions of Section 16 of the Exchange Act and related rules with respect to their purchases and sales of our securities. Moreover, we are not required to file periodic reports and financial statements with the SEC as frequently or as promptly as U.S. public companies. Accordingly, there may be less publicly available information concerning our company than there is for U.S. public companies.

In addition, foreign private issuers are not required to file their annual report on Form 20-F until 120 days after the end of each fiscal year, while U.S. domestic issuers that are accelerated filers are required to file their annual report on Form 10-K within 75 days after the end of each fiscal year. Foreign private issuers are also exempt from the Regulation Fair Disclosure, aimed at preventing issuers from making selective disclosures of material information.

We may take advantage of these exemptions until such time as we no longer qualify as a foreign private issuer. In order to maintain our current status as a foreign private issuer, either a majority of our shares must be directly or indirectly owned of record by non-residents of the United States, or a majority of our executive officers or directors may not be United States citizens or residents, more than 50% of our assets cannot be located in the United States and our business must be administered principally outside the United States.

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THE OFFERING

ADSs offered by us 2,339,000 ADSs

Offering price $2.00 per ADS

ADSs to be outstanding immediately following this offering 16,988,563 ADSs (with each ADS representing 12 Ordinary Shares), which number excludes 456,281 ADSs held in a custodial account for settlement of awards under our equity compensation plans

Ordinary Shares to be outstanding immediately following this offering 665,214,754 Ordinary Shares, which number excludes 5,475,372 ordinary shares held as ADSs in a custodial account for settlement of awards under our equity compensation plans

The ADSs Each ADS represents 12 Ordinary Shares, each with a nominal or par value of $0.0003 per share. You will have the rights of an ADS holder or beneficial owner (as applicable) as provided in the deposit agreement among us, the depositary and holders and beneficial owners of ADSs issued thereunder. To better understand the terms of our ADSs, see “Description of the Securities We are Offering.” We have also filed with the SEC a related registration statement on Form F-6 (Registration No. 333-229509), as amended, to register our ADSs. We encourage you to read the deposit agreement, the form of which is filed as an exhibit to the Form F-6.

Depositary Citibank, N.A.

Use of proceeds We intend to use the net proceeds from this offering to fund the continued clinical development of elamipretide and for working capital and general corporate purposes. See the “Use of Proceeds” section in this prospectus supplement for more information.

Risk Factors Investing in our ADSs involves a high degree of risk. You should read the “Risk Factors” section in this prospectus supplement and in our Annual Report on Form 20-F for the fiscal year ended December 31, 2019 and the other information included in, or incorporated by reference into, this prospectus supplement and the accompanying prospectus for a discussion of certain factors you should carefully consider before deciding to invest in our securities.

Nasdaq Global Market symbol Our ADSs are listed on the Nasdaq Global Market under the symbol “MITO.”

The number of Ordinary Shares to be issued and outstanding after this offering is based on 637,146,754 Ordinary

Shares issued and outstanding as of January 31, 2021, which number excludes 5,475,372 ordinary shares held as

ADSs in a custodial account for settlement of awards under our equity compensation plans. The number of Ordinary Shares to be issued and outstanding after this offering excludes:

• 45,001,937 Ordinary Shares issuable upon exercise of share options outstanding as of January 31, 2021, at a weighted-average exercise price of $0.69 per share;

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• 33,124,630 Ordinary Shares reserved for issuance under our 2019 share incentive plan, which plan includes provisions that automatically increase the number of Ordinary Shares reserved for issuance thereunder each year;

• 12,980,292 Ordinary Shares (equivalent to 1,081,691 ADSs) issuable upon vesting of grants outstanding under our 2020 ADS plan;

• 14,995,764 Ordinary Shares (equivalent to 1,249,647 ADSs) reserved for issuance under our 2020 ADS plan; which plan includes provisions that automatically increase the number of Ordinary Shares reserved for issuance thereunder each year;

• 14,691,541 Ordinary Shares reserved for issuance under our 2019 employee share purchase plan, which plan includes provisions that automatically increase the number of Ordinary Shares reserved for issuance thereunder each year;

• 46,153,846 ordinary shares issuable upon exercise of an outstanding warrant with an exercise price equal to $0.13 per share; and

• 500,000 Ordinary Shares issuable upon exercise of an outstanding warrant with an exercise price equal to $1.00 per Ordinary Share.

In addition, the discussion above assumes no additional sales of our ordinary shares or ADSs under the purchase agreement, dated June 2, 2020, between Lincoln Park Capital Fund LLC, or Lincoln Park, and us, or the Purchase

Agreement, pursuant to which we may sell, at our discretion, up to $20.0 million of our ordinary shares from time to time during the 36-month term of the Purchase Agreement.

Unless otherwise indicated, all information in this prospectus supplement assumes no exercise of the outstanding

options or warrants described above.

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RISK FACTORS

Investing in our ADSs involves a high degree of risk. You should carefully consider the following risks and the risks described in our Annual Report on Form 20-F for the fiscal year ended December 31, 2019, together with all of the other information contained in this prospectus supplement, the accompanying prospectus and in our filings with the Securities and Exchange Commission, or the SEC, that we have incorporated by reference in this prospectus supplement and the accompanying prospectus. If any of the following risks actually occur, our business, prospects, operating results and financial condition could suffer materially. In such event, the trading price of our ADSs could decline and you might lose all or part of your investment.

Risks Related to this Offering and Ownership of ADSs

The price of the ADSs has been, and is likely to continue to be, highly volatile, which could result in substantial losses for purchases of ADSs in this offering.

The price of the ADSs has been, and is likely to continue to be, highly volatile. The stock market in general and the market for smaller pharmaceutical and biotechnology companies in particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. As a result of this volatility, you may not be able to sell your ADSs at or above the public offering price and you may lose some or all of your investment. The market price for the ADSs may be influenced by many factors, including:

• our ability to commercialize or obtain regulatory approval for our product candidates, or delays in commercializing or obtaining regulatory approval;

• announcements relating to our clinical trials, including any periodic updates relating to enrollment of trial subjects, adverse events, site initiation and timing of release of interim analyses and final trial results;

• commencement or termination of collaborations for our development programs;

• failure or discontinuation of any of our development programs;

• results from, or any delays in, clinical trials relating to our product candidates, including our clinical trials for elamipretide;

• any need to suspend or discontinue clinical trials due to side effects or other safety risks, or any need to conduct studies on the long-term effects associated with the use of our product candidates;

• manufacturing issues related to our product candidates for clinical trials or future products for commercialization;

• commercial success and market acceptance of our product candidates following regulatory approval;

• undesirable side effects caused by product candidates after they have entered the market;

• ability to discover, develop and commercialize additional product candidates;

• announcements relating to collaborations that we may enter into with respect to the development or commercialization of our product candidates;

• success of our competitors in discovering, developing or commercializing products;

• strategic transactions undertaken by us;

• additions or departures of key personnel;

• product liability claims related to our clinical trials or product candidates;

• business disruptions caused by earthquakes or other natural disasters or a public health crisis (for example, an outbreak of a contagious disease such as COVID-19);

• disputes concerning our intellectual property or other proprietary rights;

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• U.S. Food and Drug Administration, European Medicines Agency, China’s National Medical Products Administration or other regulatory actions affecting us or our industry;

• healthcare reform measures in the United States;

• future sales or issuances of equity or debt securities by us;

• fluctuations in our semi-annual operating results;

• announcement or expectation of additional financing efforts;

• sales of our Ordinary Shares by us, our insiders or other shareholders;

• actual and anticipated variations in our results of operations;

• changes in securities analysts’ estimates or market perception of our financial performance;

• announcements by us of significant acquisitions, disposals, strategic alliances or joint ventures;

• market developments affecting us or the markets in which we operate;

• regulatory or legal developments, including litigation;

• the operating and share price performance of companies that investors consider to be comparable to us;

• the depth and liquidity of the market for the ADSs;

• the release or expiry of lock-up or other transfer restrictions on our Ordinary Shares and ADSs;

• general economic, political and stock market conditions in the United States and the countries in which we operate and elsewhere in the world; and

• the other factors described in this “Risk Factors” section and the “Risk Factors” sections of our Annual Report on Form 20-F for the fiscal year ended December 31, 2019, which are incorporated by reference herein.

Additionally, in the past, securities class action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for us in light of the significant stock price volatility we and other pharmaceutical companies have experienced in recent years. If we face such litigation, it could result in substantial costs and a diversion of management’s attention and resources, which could harm our business.

A significant portion of our total outstanding shares may be sold into the market, which could cause the market price of the ADSs to decline significantly, even if our business is doing well.

Sales of a substantial number of ADSs in the public market could occur at any time. These sales, or the perception in the market that holders of ADSs intend to sell a significant amount of ADSs, could reduce the market price of the ADSs. After this offering, we will have 16,988,563 ADSs outstanding, based on the 175,794,756 Ordinary Shares represented by ADSs outstanding as of January 31, 2021. These numbers exclude 5,475,372 Ordinary Shares held as 456,281 ADSs in a custodial account for settlement of awards under our equity compensation plans.

All ADSs we are selling in this offering may be resold in the public market immediately.

On June 2, 2020, we entered into the Purchase Agreement with Lincoln Park pursuant to which Lincoln Park has committed to purchase up to $20.0 million of our ordinary shares. We generally have the right to control the timing and amount of any future sales of ordinary shares to Lincoln Park. Sales of ordinary shares, if any, to Lincoln Park will depend upon market conditions and other factors to be determined by us. We may ultimately decide to sell to Lincoln Park all, some or none of the additional ordinary shares that may be available for us to sell pursuant to the Purchase Agreement. Therefore, sales to Lincoln Park could result in substantial dilution to

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the interests of other holders of our ordinary shares. Additionally, the sale of a substantial number of ordinary shares to Lincoln Park, or the anticipation of such sales, could make it more difficult for us to sell equity or equity-related securities in the future at a time and at a price that we might otherwise wish to effect sales. If and when we do sell ordinary shares to Lincoln Park, after Lincoln Park has acquired the ordinary shares, Lincoln Park may resell all, some or none of those ordinary shares at any time or from time to time in its discretion.

We have also reserved 120.8 million Ordinary Shares that we may issue under our equity compensation plans. Once registered, these shares can be freely sold in the public market upon issuance and once vested, subject to volume limitations applicable to affiliates.

We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

Our management will have broad discretion in the application of the net proceeds from this offering and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our ADSs. The failure by our management to apply these funds effectively could result in financial losses that could cause the price of our ADSs to decline and delay the development of our product candidates.

We do not anticipate paying any cash dividends on the ADSs in the foreseeable future. Accordingly, holders of ADSs must rely on capital appreciation, if any, for any return on their investment.

We have never declared nor paid cash dividends on our share capital. We currently plan to retain all of our future earnings, if any, to finance the operation, development and growth of our business. In addition, the terms of our existing loan and security agreement preclude us from paying cash dividends without the consent of our lender. As a result, capital appreciation, if any, of the ADSs will be your sole source of gain for the foreseeable future. However, if we do pay a cash dividend on our Ordinary Shares in the future, we may only pay such dividend out of our profits or share premium (subject to applicable solvency requirements) under Cayman Islands law.

If you purchase ADSs in this offering, you will suffer immediate dilution in the net tangible book value of your investment.

The public offering price of the ADSs will be substantially higher than the net tangible book value per ADS. Therefore, if you purchase ADSs in this offering, you will pay a price per ADS that substantially exceeds our net tangible book value per ADS after this offering. Based on the public offering price of $2.00 per ADS, you will experience immediate dilution of $1.88 per ADS, representing the difference between our as adjusted net tangible book value per ADS after giving effect to this offering and the public offering price. For a further description of the dilution that you will experience immediately after this offering, see “Dilution.”

You may experience future dilution in your ownership interest as a result of future equity offerings.

In order to raise additional capital, we may in the future offer additional ADSs or Ordinary Shares or other securities convertible into or exchangeable for ADSs or Ordinary Shares. We may sell securities in any other offering at effective prices that are less than the price paid by investors in this offering, and investors purchasing securities in the future could have rights superior to existing holders of ADSs.

Morningside Venture (I) Investments Limited has a controlling ownership interest in our Ordinary Shares and the ability to substantially control all matters submitted to shareholders for approval.

As of January 31, 2021, Morningside Venture (I) Investments Limited, or MVIL, beneficially owned 68.1% of our Ordinary Shares. In addition, certain entities associated within MVIL beneficially owned an additional 9.2% of our Ordinary Shares as of January 31, 2021. As a result, MVIL and such entities are able to control all matters submitted to our shareholders for approval that require an ordinary resolution or special resolution, as well as our

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management and affairs. For example, MVIL would control the election of directors and approval of any merger, consolidation or sale of all or substantially all of our assets. This concentration of ownership control may:

• delay, defer or prevent a change in control;

• entrench our management or the board of directors; or

• impede a merger, consolidation, takeover or other business combination involving us that other shareholders may desire.

MVIL owns a controlling portion of our Ordinary Shares and may have conflicts of interest with us and other shareholders in the future.

The interests of MVIL may not always be consistent with the interests of our company or of our other shareholders. Accordingly, MVIL could cause us to enter into transactions or agreements of which other holders of our Ordinary Shares would not approve or make decisions with which such holders would disagree. Gerald L. Chan, one of our directors, is a co-founder of the Morningside group, a private investment group with venture, private equity and property investments. In addition, Reenie McCarthy, our Chief Executive Officer and a director, served as a member of the investment team at Morningside Technology Advisory, LLC (and affiliates) from 1993 through 2016, and remains a director of Morningside Technology Advisory, LLC, which provides advisory services to entities associated with the Morningside group.

Although Dr. Chan is not an officer, director or employee of MVIL and has neither voting nor dispositive control over the Ordinary Shares held by MVIL and does not otherwise beneficially own such shares, as a result of his ongoing relationship with the Morningside group, transactions between us and MVIL may present an actual or perceived conflict of interest. Although Ms. McCarthy is not an officer, director or employee of MVIL, and has neither voting nor dispositive control over our Ordinary Shares held by MVIL and does not otherwise beneficially own such shares, as a result of her historic relationship with the Morningside group and her ongoing relationship with Morningside Technology Advisory, LLC, transactions between us and MVIL may present an actual or perceived conflict of interest. Any actual or perceived conflicts of interest may lead Dr. Chan and Ms. McCarthy to recuse themselves from actions of our board of directors with respect to transactions involving MVIL and its affiliates. For example, in a situation in which MVIL is adverse to us, such as if it breaches an agreement with us, a conflict could arise. We may not be able to resolve any potential conflicts, and even if we do, the resolution may be less favorable than if we were dealing with an unaffiliated party.

MVIL is in the business of making investments in companies and could from time to time acquire and hold interests in businesses that compete with us. MVIL may also pursue acquisition opportunities that may be complementary to our business, and as a result, desirable acquisitions may not be available to us. So long as MVIL continues to own a significant amount of our equity, it will continue to be able to strongly influence or effectively control our decisions.

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USE OF PROCEEDS

We estimate that the net proceeds from this offering will be approximately $4.1 million, after deducting the placement agent fees and estimated offering expenses payable by us.

We intend to use the net proceeds from this offering to fund the continued clinical development of elamipretide and for working capital and general corporate purposes.

The expected use of net proceeds from this offering represents our intentions based upon our current plans and business conditions, which could change in the future as our plans and business conditions evolve. The amounts and timing of our actual expenditures may vary significantly depending on numerous factors, including the impact of the COVID-19 pandemic on our business operations, the progress of our development of our product candidates, the status of and results from clinical trials, as well as any collaborations that we may enter into with third parties for our product candidates, and any unforeseen cash needs. As a result, our management retains broad discretion over the allocation of the net proceeds from this offering.

We anticipate that, assuming our current operating plan, the net proceeds from this offering, together with our existing cash and cash equivalents and excluding any additional potential funding or milestone payments that we may receive under the Development Funding Agreement, will enable us to fund our operating expenses and capital expenditure requirements through the second quarter of 2021. Based on our current operating plan, we will require additional capital to advance elamipretide through pivotal trials for indications other than Barth and to advance our other product candidates through later-stage clinical development, as well as to commercialize any of our product candidates if we receive regulatory approval. We have based these estimates on assumptions that may prove to be wrong, including assumptions regarding the clinical trials necessary for FDA approval of our product candidates, and we could use our capital resources sooner than we currently expect. Due to the numerous risks and uncertainties associated with product development, including risks and uncertainties with respect to successful enrollment and completion of clinical trials, at this time we cannot reasonably estimate the amount of additional funding that will be necessary to complete the clinical development of any of our product candidates. If we receive regulatory approval for elamipretide, SBT-272 or any of our other product candidates, we expect to incur significant commercialization expenses related to product manufacturing, sales, marketing and distribution. Accordingly, we will be required to obtain further funding through public or private equity offerings, debt financings, collaborations and licensing arrangements or other sources.

Pending use of the net proceeds as described above, we intend to invest the net proceeds in short-term, interest-bearing, investment-grade securities.

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DIVIDEND POLICY

We have never declared or paid any cash dividends on our share capital. We intend to retain all of our future

earnings, if any, to finance the growth and development of our business, and we do not intend to pay cash

dividends to the holders of our Ordinary Shares for the foreseeable future. In addition, the terms of our existing

loan and security agreement preclude us from paying cash dividends without the consent of our lender. However,

if at any time we do determine to pay a cash dividend on our Ordinary Shares in the future, we will only be able pay such dividend out of our profits or share premium (subject to applicable solvency requirements) under Cayman Islands law.

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DILUTION

If you invest in the ADSs in this offering, your ownership interest will be diluted immediately to the extent of the difference between the offering price per ADS and the as adjusted net tangible book value per ADS immediately after this offering.

Our historical net tangible book value as of September 30, 2020 was approximately $2.3 million, or $0.004 per ordinary share and $0.046 per ADS. Each ADS represents 12 ordinary shares. Our net tangible book value per share represents the amount of our total tangible assets less our total liabilities, divided by the number of ordinary shares outstanding as of September 30, 2020.

After giving effect to our issuance and sale of 2,339,000 ADSs representing 28,068,000 Ordinary Shares in this offering at an offering price of $2.00 per ADS, after deducting the placement agent fees and estimated offering expenses payable by us, our as adjusted net tangible book value as of September 30, 2020 would have been $6.4 million, or $0.010 per Ordinary Share and $0.122 per ADS. This represents an immediate increase in net tangible book value of $0.076 per ADS to existing shareholders and an immediate dilution in as adjusted net tangible book value of $1.878 per ADS to new investors purchasing ADSs in this offering. The following table illustrates this dilution on a per ADS basis:

Public offering price per ADS			$	2.00
Net tangible book value per ADS as of September 30, 2020	$	0.046
Increase in net tangible book value attributable to investors purchasing ADSs in this offering		0.076
As adjusted net tangible book value per ADS after this offering				0.122
Dilution per ADS to new investors			$	1.878

The discussion and table above are based on 598,753,522 Ordinary Shares issued and outstanding as of September 30, 2020, which number excludes 2,289,960 ordinary shares held as ADSs in a custodial account as of that date for settlement of awards under our equity compensation plans, and exclude the following as of January 31, 2021:

• 45,001,937 Ordinary Shares issuable upon exercise of share options outstanding at a weighted-average exercise price of $0.69 per share;

• 33,124,630 Ordinary Shares reserved for issuance under our 2019 share incentive plan, which plan includes provisions that automatically increase the number of Ordinary Shares reserved for issuance thereunder each year;

• 12,980,292 Ordinary Shares (equivalent to 1,081,691 ADSs) issuable upon vesting of grants outstanding under our 2020 ADS plan;

• 14,995,764 Ordinary Shares (equivalent to 1,249,647 ADSs) reserved for issuance under our 2020 ADS plan; which plan includes provisions that automatically increase the number of Ordinary Shares reserved for issuance thereunder each year;

• 14,691,541 Ordinary Shares reserved for issuance under our 2019 employee share purchase plan, which plan includes provisions that automatically increase the number of Ordinary Shares reserved for issuance thereunder each year;

• 46,153,846 ordinary shares issuable upon exercise of an outstanding warrant with an exercise price equal to $0.13 per share;

• 500,000 Ordinary Shares issuable upon exercise of an outstanding warrant with an exercise price equal to $1.00 per Ordinary Share;

• 34,133,352 Ordinary Shares (equivalent to 2,844,446 ADSs) issued in the 2020 Offering;

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• 4,259,880 Ordinary Shares (equivalent to 354,990 ADSs) that were released subsequent to September 30, 2020 under our 2020 ADS plan; and

• An additional 3,185,412 Ordinary Shares held as ADSs in the custodial account for settlement of awards under our equity compensation plans.

To the extent that share options or warrants outstanding as of January 31, 2021 have been or may be exercised or other shares are issued, investors purchasing our ADSs in this offering may experience further dilution.

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DESCRIPTION OF THE SECURITIES WE ARE OFFERING

ADSs

In this offering, we are offering 2,339,000 ADSs. The material terms and provisions of our ADSs are described under the heading “Description of American Depositary Shares” in the accompanying prospectus.

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TAXATION

Material U.S. Federal Income Tax Considerations for U.S. Holders

The following discussion describes the material U.S. federal income tax consequences relating to the ownership and disposition of our Ordinary Shares or ADSs by U.S. Holders (as defined below). This discussion applies to U.S. Holders that purchase our ADSs pursuant to this offering and hold such ADSs as a capital asset (generally, property held for investment). This discussion is based on the U.S. Internal Revenue Code of 1986, as amended, or the Code, administrative pronouncements, judicial decisions and final, temporary, and proposed U.S. Treasury Regulations, all as in effect on the date hereof and all of which are subject to change, possibly with retroactive effect. This discussion does not address all of the U.S. federal income tax consequences that may be relevant to specific U.S. Holders in light of their particular circumstances, including state and local tax consequences, estate tax consequences, alternative minimum tax consequences and tax consequences applicable to U.S. Holders subject to special rules, such as:

• banks, insurance companies and certain other financial institutions;

• U.S. expatriates and certain former citizens or long-term residents of the United States;

• dealers or traders in securities who use a mark-to-market method of tax accounting;

• persons holding Ordinary Shares or ADSs as part of a hedging transaction, “straddle,” wash sale, conversion transaction or integrated transaction or persons entering into a constructive sale with respect to Ordinary Shares or ADSs;

• persons whose “functional currency” for U.S. federal income tax purposes is not the U.S. dollar;

• brokers, dealers or traders in securities, commodities or currencies;

• tax-exempt entities or government organizations;

• S corporations, partnerships or other entities or arrangements classified as partnerships for U.S. federal income tax purposes;

• regulated investment companies or real estate investment trusts;

• persons who acquired our Ordinary Shares or ADSs pursuant to the exercise of any employee share option or otherwise as compensation;

• persons that own or are deemed to own ten percent or more of our shares; and

• persons holding our Ordinary Shares or ADSs in connection with a trade or business, permanent establishment or fixed base outside the United States.

If an entity treated as a partnership for U.S. federal income tax purposes holds our Ordinary Shares or ADSs, the U.S. federal income tax consequences relating to an investment in such Ordinary Shares or ADSs will depend upon the status of the partner and the activities of the partnership.

A “U.S. Holder” is a holder who, for U.S. federal income tax purposes, is a beneficial owner of Ordinary Shares or ADSs and is:

• an individual who is a citizen or resident of the United States;

• a corporation, or other entity taxable as a corporation, created or organized in or under the laws of the United States, any state thereof or the District of Columbia;

• an estate the income of which is subject to U.S. federal income tax regardless of its source; or

• a trust if (i) a U.S. court is able to exercise primary supervision over the administration of the trust and one or more U. S. persons has authority to control all substantial decisions of the trust or (ii) the trust has made a valid election to be treated as a U.S. person under applicable U.S. Treasury Regulations.

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Persons considering an investment in our ADSs should consult their own tax advisors as to the particular tax consequences applicable to them relating to the purchase, ownership and disposition of our Ordinary Shares or ADSs, including the applicability of U.S. federal, state and local tax laws and non-U.S. tax laws.

The discussion below assumes that the representations contained in the deposit agreement are true and that the obligations in the deposit agreement and any related agreement will be complied with in accordance with their terms. Generally, a holder of an ADS should be treated for U.S. federal income tax purposes as holding the Ordinary Shares represented by the ADS. Accordingly, no gain or loss will be recognized upon an exchange of ADSs for the underlying Ordinary Shares represented by such ADSs. The U.S. Treasury has expressed concerns that intermediaries in the chain of ownership between the holder of an ADS and the issuer of the security underlying the ADS may be taking actions that are inconsistent with the beneficial ownership of the underlying security. Accordingly, the creditability of foreign taxes, if any, as described below, could be affected by actions taken by intermediaries in the chain of ownership between the holders of ADSs and our company if as a result of such actions the holders of ADSs are not properly treated as beneficial owners of the underlying Ordinary Shares.

Passive Foreign Investment Company Rules

We are a foreign corporation, within the meaning of the Code. If we are classified as a passive foreign investment company, or PFIC, in any taxable year, certain adverse U.S. federal income tax consequences could apply to a U.S. Holder as a result of that classification.

A non-U.S. corporation will be classified as a PFIC for any taxable year in which, after applying certain look-through rules, either:

• at least 75% of its gross income is passive income, or the PFIC income test; or

• on average at least 50% of the value of its assets, determined on a quarterly basis, is attributable to assets that produce passive income (or no income) or are held for the production of passive income, or the PFIC asset test.

Passive income for this purpose generally includes, among other things, dividends, interest, royalties, rents and gains from the sale or exchange of property that gives rise to passive income (or no income). Assets that produce or are held for the production of passive income generally include cash, even if held as working capital or raised in a public offering, marketable securities and other assets that may produce passive income. Generally, in determining whether a non-U.S. corporation is a PFIC, a proportionate share of the income and assets of each corporation in which it owns, directly or indirectly, at least a 25% interest (by value) is taken into account.

Based on our estimated gross income and the average value of our gross assets, taking into account the public offering price of the ADSs in this offering, the expected price of our ADSs following this offering and the nature of our business, we do not believe that we were a PFIC for our tax year ended December 31, 2019, and do not currently expect to be a PFIC during our tax year ending December 31, 2020. However, there can be no assurance that we will not be classified as a PFIC for the current taxable year or any prior or future taxable year. The determination of whether we are a PFIC is a fact-intensive determination made on an annual basis and the applicable law is subject to varying interpretation.

A separate determination must be made after the close of each taxable year as to whether we are a PFIC for that year. As a result, our PFIC status may change from year to year. The total value of our assets for purposes of the PFIC asset test frequently (though not invariably) may be inferred using the market price of our Ordinary Shares or ADSs, which may fluctuate considerably and thereby affect the determination of our PFIC status for any given taxable year.

If we are a PFIC in any taxable year during which a U.S. Holder owns our Ordinary Shares or ADSs, the U.S. Holder could be liable for additional taxes and interest charges under the “PFIC excess distribution regime” upon

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(i) a distribution paid during a taxable year, if that distribution is greater than 125% of the average annual distributions paid in the three preceding taxable years, or, if shorter, the U.S. Holder’s holding period for our Ordinary Shares or ADSs, and (ii) any gain recognized on a sale, exchange or other disposition, including a pledge, of our Ordinary Shares or ADSs, whether or not we continue to be a PFIC. Under the PFIC excess distribution regime, the tax on such distribution or gain would be determined by allocating the distribution or gain ratably over the U.S. Holder’s holding period for our Ordinary Shares or ADSs. The amount allocated to the current taxable year (i.e., the year in which the distribution occurs or the gain is recognized) and any year prior to the first taxable year in which we are a PFIC will be taxed as ordinary income earned in the current taxable year. The amount allocated to other taxable years will be taxed at the highest marginal rates in effect for individuals or corporations, as applicable, to ordinary income for each such taxable year, and an interest charge, in the amounts generally applicable to underpayments of tax over the relevant period, will be added to the tax.

If we are classified as a PFIC for any year during which a U.S. Holder holds our Ordinary Shares or ADSs, we must generally continue to be treated as a PFIC by that holder for all succeeding years during which the U.S. Holder holds such Ordinary Shares or ADSs, regardless of whether we continue to meet the tests described above, unless we cease to be a PFIC and the U.S. Holder makes a “deemed sale” election under the PFIC rules with respect to our Ordinary Shares or ADSs. If the “deemed sale” election is made, the U.S. Holder will be deemed to have sold our Ordinary Shares or ADSs it holds at their fair market value on the last day of the last taxable year in which we qualified as a PFIC, and any gain recognized from such deemed sale would be taxed under the PFIC excess distribution regime. After the deemed sale election, the U.S. Holder’s Ordinary Shares or ADSs would not be treated as shares of a PFIC unless we subsequently become a PFIC. If we are a PFIC for any taxable year during which a U.S. Holder holds our Ordinary Shares or ADSs, and one of our non-U.S. subsidiaries is also a PFIC (i.e., a lower-tier PFIC), such U.S. Holder would be treated as owning a proportionate amount (by value) of the shares of the lower-tier PFIC and would be taxed under the PFIC excess distribution regime on distributions by the lower-tier PFIC and on gain from the disposition of shares of the lower-tier PFIC even though such U.S. Holder would not receive the proceeds of those distributions or dispositions. Any of our non-U.S. subsidiaries that have elected to be disregarded as entities separate from us or as partnerships for U.S. federal income tax purposes would not be corporations under U.S. federal income tax law and accordingly, cannot be classified as lower-tier PFICs. However, non-U.S. subsidiaries that have not made such election may be classified as lower-tier PFICs if we are a PFIC during a U.S. Holder’s holding period and the subsidiary meets the PFIC income test or PFIC asset test.

If we are a PFIC, a U.S. Holder will not be subject to tax under the PFIC excess distribution regime on distributions or gain recognized on our Ordinary Shares or ADSs if a valid “mark-to-market” election is made by the U.S. Holder for our Ordinary Shares or ADSs, provided that the Ordinary Shares or ADSs are “marketable.” Our Ordinary Shares or ADSs will be considered marketable if they are “regularly traded” on a “qualified exchange” within the meaning of applicable U.S. Treasury Regulations. A class of stock is regularly traded during any calendar year during which such class of stock is traded, other than in de minimis quantities, on at least 15 days during each calendar quarter.

Our ADSs will be considered marketable as long as they remain listed on The Nasdaq Global Market and are regularly traded. A mark-to-market election will not apply to our Ordinary Shares or ADSs for any taxable year during which we are not a PFIC, but will remain in effect with respect to any subsequent taxable year in which we become a PFIC. Such election will not apply to any of our non-U.S. subsidiaries. Accordingly, a U.S. Holder may continue to be subject to tax under the PFIC excess distribution regime with respect to any lower-tier PFICs notwithstanding the U.S. Holder’s mark-to-market election for our Ordinary Shares or ADSs.

An electing U.S. Holder generally must take into account as ordinary income each year an amount equal to the excess, if any, of the fair market value of our Ordinary Shares or ADSs held at the end of such taxable year over the adjusted tax basis of such Ordinary Shares or ADSs. The U.S. Holder may also claim an ordinary loss deduction for the excess, if any, of the U.S. Holder’s adjusted tax basis of such Ordinary Shares or ADSs over their fair market value at the end of the taxable year, but only to the extent of any net mark-to-market gains for

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prior years. The U.S. Holder’s tax basis in our Ordinary Shares or ADSs would be adjusted to reflect any income or loss recognized as a result of the mark-to-market election. Any gain from a sale, exchange or other disposition of our Ordinary Shares or ADSs in any taxable year in which we are a PFIC would be treated as ordinary income and any loss from such sale, exchange or other disposition would be treated first as ordinary loss (to the extent of any net mark-to-market gains for prior years) and thereafter as capital loss. If, after having been a PFIC for a taxable year, we cease to be classified as a PFIC because we no longer meet the PFIC income or PFIC asset test, the U.S. Holder would not be required to take into account any latent gain or loss in the manner described above and any gain or loss recognized on the sale or exchange of the Ordinary Shares or ADSs would be classified as a capital gain or loss. Once made, the election cannot be revoked without the consent of the Internal Revenue Service, or the IRS, unless the ADSs cease to be marketable.

The tax consequences that would apply if we are a PFIC would also be different from those described above if a U.S. Holder were able to make a valid qualified electing fund, or QEF, election. As we do not expect to provide U.S. Holders with the information necessary for a U.S. Holder to make a QEF election, prospective investors should assume that a QEF election will not be available.

Unless otherwise provided by the U.S. Treasury, each U.S. shareholder of a PFIC is required to file an annual report containing such information as the U.S. Treasury may require. A U.S. Holder’s failure to file the annual report will cause the statute of limitations for such U.S. Holder’s U.S. federal income tax return to remain open with regard to the items required to be included in such report until three years after the U.S. Holder files the annual report, and, unless such failure is due to reasonable cause and not willful neglect, the statute of limitations for the U.S. Holder’s entire U.S. federal income tax return will remain open during such period.

Distributions

While we do not expect to pay any dividends in the near future, in the event any dividends are paid, subject to the discussion above under “Passive Foreign Investment Company Rules,” a U.S. Holder that receives a distribution with respect to our Ordinary Shares or ADSs generally will be required to include the gross amount of such distribution in gross income as a dividend when actually or constructively received to the extent of the U.S. Holder’s pro rata share of our current and/or accumulated earnings and profits (as determined under U.S. federal income tax principles). To the extent a distribution received by a U.S. Holder is not a dividend because it exceeds the U.S. Holder’s pro rata share of our current and accumulated earnings and profits, it will be treated first as a tax-free return of capital and reduce (but not below zero) the adjusted tax basis of the U.S. Holder’s Ordinary Shares or ADSs. To the extent the distribution exceeds the adjusted tax basis of the U.S. Holder’s Ordinary Shares or ADSs, the remainder will be taxed as capital gain. Because we may not account for our earnings and profits in accordance with U.S. federal income tax principles, U.S. Holders should expect all distributions to be reported to them as dividends. Subject to applicable limitations, dividends paid to certain non-corporate U.S. Holders may be taxable at preferential rates applicable to “qualified dividend income.” However, the qualified dividend income treatment may not apply if we are treated as a PFIC with respect to the U.S. Holder. Distributions on our Ordinary Shares or ADSs that are treated as dividends generally will constitute income from sources outside the United States for foreign tax credit purposes and generally will constitute passive category income. Such dividends will not be eligible for the “dividends received’’ deduction generally allowed to corporate shareholders with respect to dividends received from U.S. corporations.

Dividends will be included in a U.S. Holder’s income on the date of the depositary’s receipt of the dividend. The amount of any dividend income paid in foreign currency will be the U.S. dollar amount calculated by reference to the exchange rate in effect on the date of actual or constructive receipt, regardless of whether the payment is in fact converted into U.S. dollars. If the dividend is converted into U.S. dollars on the date of receipt, a U.S. Holder should not be required to recognize foreign currency gain or loss with respect to the dividend income. A U.S. Holder may have foreign currency gain or loss if the dividend is converted into U.S. dollars after the date of receipt.

S-23

Sale, Exchange or Other Disposition of Our Ordinary Shares or ADSs

Subject to the discussion above under “Passive Foreign Investment Company Rules,” a U.S. Holder generally will recognize capital gain or loss for U.S. federal income tax purposes upon the sale, exchange or other disposition of our Ordinary Shares or ADSs in an amount equal to the difference, if any, between the amount realized (i.e., the amount of cash plus the fair market value of any property received) on the sale, exchange or other disposition and such U.S. Holder’s adjusted tax basis in the Ordinary Shares or ADSs. Such capital gain or loss generally will be long-term capital gain taxable at a reduced rate for non-corporate U.S. Holders or long-term capital loss if, on the date of sale, exchange or other disposition, the Ordinary Shares or ADSs were held by the U.S. Holder for more than one year. Any capital gain of a non-corporate U.S. Holder that is not long-term capital gain is taxed at ordinary income rates. The deductibility of capital losses is subject to limitations. Any gain or loss recognized from the sale or other disposition of our Ordinary Shares or ADSs will generally be gain or loss from sources within the United States for U.S. foreign tax credit purposes.

Medicare Tax

Certain U.S. Holders that are individuals, estates or trusts and whose income exceeds certain thresholds generally are subject to a 3.8% tax on all or a portion of their net investment income, which may include their gross dividend income and net gains from the disposition of our Ordinary Shares or ADSs.

Information Reporting and Backup Withholding

U.S. Holders may be required to file certain U.S. information reporting returns with the IRS with respect to an investment in our Ordinary Shares or ADSs, including, among others, IRS Form 8938 (Statement of Specified Foreign Financial Assets). As described above under “Passive Foreign Investment Company Rules,” each U.S. Holder who is a shareholder of a PFIC must file an annual report containing certain information. U.S. Holders paying more than $100,000 for our Ordinary Shares or ADSs may be required to file IRS Form 926 (Return by a U.S. Transferor of Property to a Foreign Corporation) reporting this payment. Substantial penalties may be imposed upon a U.S. Holder that fails to timely comply with the required information reporting.

Dividends on and proceeds from the sale or other disposition of our ADSs may be reported to the IRS unless the U.S. Holder establishes a basis for exemption. Backup withholding may apply to amounts subject to reporting if the holder (i) fails to provide an accurate U.S. taxpayer identification number or otherwise establish a basis for exemption or (ii) is described in certain other categories of persons. However, U.S. Holders that are corporations generally are excluded from these information reporting and backup withholding tax rules.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules generally will be allowed as a refund or a credit against a U.S. Holder’s U.S. federal income tax liability if the required information is furnished by the U.S. Holder on a timely basis to the IRS.

Cayman Islands Taxation

Prospective investors should consult their professional advisors on the possible tax consequences of buying, holding or selling any ADSs under the laws of their country of citizenship, residence or domicile.

The following is a discussion on certain Cayman Islands income tax consequences of an investment in the ADSs. The discussion is a general summary of present law, which is subject to prospective and retroactive change. It is not intended as tax advice, does not consider any investor’s particular circumstances and does not consider tax consequences other than those arising under Cayman Islands law.

No stamp duty, capital duty, registration or other issue or documentary taxes are payable in the Cayman Islands on the creation, issuance or delivery of the ADSs. The Cayman Islands currently have no form of income,

S-24

corporate or capital gains tax and no estate duty, inheritance tax or gift tax. There are currently no Cayman Islands taxes or duties of any nature on gains realized on a sale, exchange, conversion, transfer or redemption of the ADSs. Payments of dividends and capital in respect of the ADSs or Ordinary Shares will not be subject to taxation in the Cayman Islands and no withholding will be required on the payment of interest and principal or a dividend or capital to any holder of the ADSs, nor will gains derived from the disposal of the ADSs be subject to Cayman Islands income or corporation tax as the Cayman Islands currently have no form of income or corporation taxes.

Pursuant to section 6 of the Tax Concessions Law (2018 Revision) of the Cayman Islands, we have obtained an undertaking from the Governor-in-Cabinet:

• that no law which is enacted in the Cayman Islands imposing any tax to be levied on profits, income, gains or appreciation shall apply to us or our operations; and

• that no such tax or any tax in the nature of estate duty or inheritance tax shall be payable on or in respect of the ADSs or Ordinary Shares, debentures or other obligations of ours.

The undertaking for the Company is for a period of twenty years from April 11, 2006.

S-25

PLAN OF DISTRIBUTION

We have engaged H.C. Wainwright & Co., LLC (“Wainwright” or the “placement agent”), to act as our exclusive placement agent to solicit offers to purchase the ADSs offered by this prospectus supplement and the accompanying prospectus. Wainwright is not purchasing or selling any ADSs, nor is it required to arrange for the purchase and sale of any specific number or dollar amount of ADSs, but only to use its reasonable best efforts to arrange for the sale of the ADSs by us. Therefore, we may not sell the entire amount of the ADSs being offered hereby. There is no minimum amount of proceeds that is a condition to the closing of this offering. We will enter into a securities purchase agreement directly with the institutional investors that purchase our ADSs in this offering. Wainwright may engage one or more sub-placement agents or selected dealers in connection with this offering. We will only sell shares in this offering to investors who have entered into the securities purchase agreement.

Fees and Expenses

The following table shows the per ADS and total placement agent fees we will pay in connection with the sale of the ADSs in this offering, assuming the purchase of all of the ADSs we are offering.

Per ADS placement agent cash fee	$	0.12
Total placement agent cash fee	$	280,680

We have agreed to pay the placement agent a total cash fee equal to 6.0% of the gross proceeds of this offering. We will also pay to the placement agent a management fee equal 1.0% of the gross proceeds of this offering and a non-accountable expense allowance of $35,000 and to reimburse the placement agent’s reasonable and documented expenses in connection with this offering, including fees and expenses of outside counsel, in the amount of up to $50,000 and the placement agent’s clearing expenses in the amount of up to $15,950. We estimate the total offering expenses of this offering that will be payable by us, excluding the placement agent fees and expenses, will be approximately $200,000.

Right of First Refusal

Pursuant to our engagement letter with the placement agent, we have granted a right of first refusal to the placement agent to participate in any public offering (including an at-the-market facility), private placement or any other capital-raising financing of equity, equity-linked or debt securities using an underwriter or placement agent, subject to certain exclusions, with (i) at least 50% of the economics in connection with a financing with gross proceeds to us of $40 million or less or (ii) at least 35% of the economics in connection with a financing with gross proceeds to us of over $40 million, at any time prior to the six-month anniversary of the date of the closing of the offering.

Other Relationships

The placement agent acted as our exclusive placement agent for the registered direct offering we consummated in November 2020, for which it received compensation. The placement agent may, from time to time, engage in transactions with or perform services for us in the ordinary course of its business and may continue to receive compensation from us for such services.

Lock-up

Pursuant to the securities purchase agreement, subject to certain exceptions, we and our subsidiaries have agreed not to issue, enter into any agreement to issue or announce the issuance or proposed issuance of any Ordinary Shares, ADSs or securities convertible into Ordinary Shares or ADSs for a period of 45 days following the date of this prospectus supplement. Pursuant to the securities purchase agreement, we have also agreed not to enter into any “variable rate transactions” for a period of 90 days following the consummation of this offering, subject to certain exceptions.

S-26

Determination of Offering Price

The offering price of the securities we are offering was negotiated between us and the investors, in consultation with the placement agent based on the trading of our ADSs prior to the offering, among other things. Other factors considered in determining the offering price of the securities we are offering include the history and prospects of our company, the stage of development of our business, our business plans for the future and the extent to which they have been implemented, an assessment of our management, general conditions of the securities markets at the time of the offering and such other factors as were deemed relevant.

Nasdaq Listing

Our ADSs are listed on the Nasdaq Global Market under the symbol “MITO.”

Indemnification

We have agreed to indemnify the placement agent against certain liabilities, including liabilities under the Securities Act of 1933, as amended, or the Securities Act, or to contribute to payments the placement agent may be required to make with respect to any of these liabilities.

Regulation M

The placement agent may be deemed to be an underwriter within the meaning of Section 2(a)(11) of the Securities Act and any fees received by it and any profit realized on the sale of the securities by it while acting as principal might be deemed to be underwriting discounts or commissions under the Securities Act. The placement agent will be required to comply with the requirements of the Securities Act and Securities Exchange Act of 1934, as amended, or the Exchange Act, including, without limitation, Rule 10b-5 and Regulation M under the Exchange Act. These rules and regulations may limit the timing of purchases and sales of our securities by the placement agent. Under these rules and regulations, the placement agent may not (i) engage in any stabilization activity in connection with our securities and (ii) bid for or purchase any of our securities or attempt to induce any person to purchase any of our securities, other than as permitted under the Exchange Act, until it has completed its participation in the distribution.

S-27

LEGAL MATTERS

Legal matters with respect to U.S. federal law in connection with this offering will be passed upon for us by Wilmer Cutler Pickering Hale and Dorr LLP, Boston, Massachusetts. Certain legal matters with respect to Cayman Islands law in connection with the validity of the ADSs being offered by this prospectus supplement and other legal matters will be passed upon for us by Walkers, George Town, Cayman Islands. Ellenoff Grossman & Schole LLP, New York, New York, has acted as counsel for the placement agent in connection with certain legal matters related to this offering.

EXPERTS

The financial statements, incorporated in this prospectus supplement by reference from the Company’s Annual Report on Form 20-F for the year ended December 31, 2019, have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report, which is incorporated herein by reference, which report expresses an unqualified opinion on the financial statements and includes an explanatory paragraph referring to the Company’s ability to continue as a going concern. Such financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

The registered business address of Deloitte & Touche LLP is 200 Berkeley Street, Boston, Massachusetts 02116.

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WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement on Form F-3, including relevant exhibits and schedules under the Securities Act, with respect to underlying securities to be sold in this offering. This prospectus supplement, which constitutes a part of such registration statement, does not contain all of the information contained in the registration statement. A related registration statement on F-6 has been filed with the SEC to register the ADSs representing the Ordinary Shares. You should read the registration statements and their respective exhibits and schedules for further information with respect to us and our ADSs.

We are subject to periodic reporting and other informational requirements of the Exchange Act as applicable to foreign private issuers. Accordingly, we are required to file reports, including annual reports on Form 20-F, and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC’s website at www.sec.gov. Copies of certain information filed by us with the SEC and the filings incorporated by reference in this prospectus are also available on our website at www.stealthbt.com. Our website is not a part of this prospectus supplement and is not incorporated by reference in this prospectus supplement.

As a foreign private issuer, we are exempt under the Exchange Act from, among other things, the rules prescribing the furnishing and content of proxy statements, and our executive officers, directors and principal shareholders are exempt from the reporting and short-swing profit recovery provisions contained in Section 16 of the Exchange Act. In addition, we are not required under the Exchange Act to file periodic reports and financial statements with the SEC as frequently or as promptly as U.S. companies whose securities are registered under the Exchange Act. However, we intend to furnish the depositary with our annual reports, which will include a review of operations and annual audited consolidated financial statements prepared in conformity with U.S. GAAP, and all notices of shareholders’ meeting and other reports and communications that are made generally available to our shareholders. The depositary shall arrange, at our request and at our expense, to provide copies of such notices, reports and to all holders of ADSs or make such notices, reports and other communications available to all holders of ADSs on a basis similar to that for holders of Ordinary Shares or other deposited securities or on such other basis as we may advise the depositary or as may be required by any applicable law, regulation or stock exchange requirement.

S-29

INCORPORATION BY REFERENCE

The SEC allows us to incorporate by reference much of the information we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference in this prospectus supplement is considered to be part of this prospectus supplement and the accompanying prospectus. Because we are incorporating by reference future filings with the SEC, this prospectus supplement and the accompanying prospectus are continually updated and those future filings may modify or supersede some of the information included or incorporated in this prospectus supplement and the accompanying prospectus. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus supplement, the accompanying prospectus or in any document previously incorporated by reference herein or therein have been modified or superseded. This prospectus supplement incorporates by reference the documents listed below (File No. 001-38810) and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (in each case, other than those documents or the portions of those documents not deemed to be filed) and, to the extent designated therein, reports on Form 6-K that we furnish to the SEC, until the offering of the securities offered hereby is terminated or completed:

• Annual Report on Form 20-F for the fiscal year ended December 31, 2019, filed with the SEC on April 1, 2020;

• Our Reports of Foreign Private Issuer on Form 6-K, filed with the SEC on January 7, 2020, April 13, 2020, May  7, 2020, June 3, 2020, August  6, 2020, August 7, 2020, November 4, 2020; November 5, 2020, November  19, 2020, November 23, 2020 and December 7, 2020; and

• The description of our Ordinary Shares and ADSs contained in our registration statement on Form 8-A, filed with the SEC under the Exchange Act on February 12, 2019, including any amendment or report filed for the purpose of updating such description.

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address or telephone number:

c/o Stealth BioTherapeutics Inc.

140 Kendrick Street

Needham, MA 02494

(617) 600-6888

You also may access these filings on our website at www.stealthbt.com. Our website and the information contained on that site, or connected to that site, are not incorporated into this prospectus supplement.

S-30

$75,000,000

PROSPECTUS

American Depositary Shares representing Ordinary Shares

Units

Warrants

We may issue securities from time to time in one or more offerings of up to $75,000,000 in aggregate offering price. This prospectus describes the general terms of these securities and the general manner in which these securities will be offered. We will provide the specific terms of these securities in supplements to this prospectus. The prospectus supplements will also describe the specific manner in which these securities will be offered and may also supplement, update or amend information contained in this document. You should read this prospectus and any applicable prospectus supplement carefully before you invest.

Pursuant to General Instruction I.B.5 of Form F-3, in no event will we sell, pursuant to the registration statement of which this prospectus forms a part, securities in a public primary offering with a value exceeding one-third of the aggregate market value of our issued and outstanding ordinary shares held by non-affiliates, or our public float, in any 12-month period, so long as our public float remains below $75,000,000. Our public float, as of the filing date of this prospectus was $18,064,644, based on 5,884,249 American Depositary Shares, or ADSs, each representing 12 ordinary shares, $0.0003 par value per share, issued and outstanding and held by non-affiliates, and a per share price of $3.07 based on the closing sale price of our ADSs on March 3, 2020. We have not offered any securities pursuant to General Instruction I.B.5 of Form F-3 during the 12 calendar months prior to and including the date of this prospectus.

We may offer these securities in amounts, at prices and on terms determined at the time of offering. The securities may be sold directly to you, through agents, or through underwriters and dealers. If agents, underwriters or dealers are used to sell the securities, we will name them and describe their compensation in a prospectus supplement.

Our ADSs are listed on The Nasdaq Global Market under the symbol “MITO.”

Investing in these securities involves significant risks. See “Risk Factors” included in any accompanying prospectus supplement and in the documents incorporated by reference in this prospectus for a discussion of the factors you should carefully consider before deciding to purchase these securities.

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

The date of this prospectus is April 10, 2020.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS	1
RISK FACTORS	2
WHERE YOU CAN FIND MORE INFORMATION	3
INCORPORATION BY REFERENCE	3
FORWARD-LOOKING STATEMENTS	4
THE COMPANY	5
CAPITALIZATION AND INDEBTEDNESS	6
USE OF PROCEEDS	7
DESCRIPTION OF SHARE CAPITAL AND ARTICLES OF ASSOCIATION	8
DESCRIPTION OF AMERICAN DEPOSITARY SHARES	22
DESCRIPTION OF UNITS	33
DESCRIPTION OF WARRANTS	33
FORMS OF SECURITIES	34
TAXATION	36
PLAN OF DISTRIBUTION	36
LEGAL MATTERS	39
EXPERTS	39
EXPENSES	39
ENFORCEMENT OF CIVIL LIABILITIES	40

i

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the U.S. Securities and Exchange Commission, which we refer to as the SEC, utilizing a “shelf” registration process. Under this shelf registration process, we may from time to time sell any combination of the securities described in this prospectus in one or more offerings for an aggregate initial offering price of up to $75,000,000.

This prospectus provides you with a general description of the securities we may offer. Each time we sell securities, we will provide one or more prospectus supplements that will contain specific information about the terms of the offering. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and the accompanying prospectus supplement together with the additional information described under the heading “Where You Can Find More Information” beginning on page 3 of this prospectus.

You should rely only on the information contained in or incorporated by reference in this prospectus, any accompanying prospectus supplement or in any related free writing prospectus filed by us with the SEC. We have not authorized anyone to provide you with different information. This prospectus and any accompanying prospectus supplement do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in this prospectus or such accompanying prospectus supplement or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful. You should assume that the information appearing in this prospectus, any prospectus supplement, the documents incorporated by reference and any related free writing prospectus is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

Unless the context specifically indicates otherwise, references in this prospectus to “Stealth BioTherapeutics Corp,” “Stealth,” “the Company,” “we,” “our,” “us,” “our company,” or similar terms refer to Stealth BioTherapeutics Corp and its consolidated subsidiaries, or any one or more of them as the context may require.

1

RISK FACTORS

An investment in our securities involves a high degree of risk. Before deciding whether to invest in our securities, you should consider carefully the risks and uncertainties described under the section captioned “Risk Factors” in the applicable prospectus supplement and contained in our most recent Annual Report on Form 20-F and other filings we make with the SEC from time to time, which are incorporated by reference herein in their entirety, together with other information in this prospectus, the information and documents incorporated by reference in this prospectus, and in any prospectus supplement or free writing prospectus that we authorize for use in connection with this offering. If any of these risks actually occurs, our business, financial condition, results of operations or cash flow could suffer materially. In such event, the trading price of ADSs could decline and you might lose all or part of your investment.

2

WHERE YOU CAN FIND MORE INFORMATION

We are subject to periodic reporting and other informational requirements of the Securities Exchange Act of 1934, as amended, or the Exchange Act, as applicable to foreign private issuers. Accordingly, we are required to file reports, including annual reports on Form 20-F, and other information with the SEC. As a foreign private issuer, we are exempt from the rules of the Exchange Act prescribing the furnishing and content of proxy statements to shareholders under the federal proxy rules contained in Sections 14(a), (b) and (c) of the Exchange Act, and our “insiders” are exempt from the reporting and short-swing profit recovery provisions contained in Section 16 of the Exchange Act. Our SEC filings are available to the public over the Internet at the SEC’s website at http://www.sec.gov. Copies of certain information filed by us with the SEC are also available on our website at http://www.stealthbt.com. Our website is not a part of this prospectus and is not incorporated by reference in this prospectus.

This prospectus is part of a registration statement we filed with the SEC. This prospectus omits some information contained in the registration statement in accordance with SEC rules and regulations. You should review the information and exhibits in the registration statement for further information about us and our consolidated subsidiaries and the securities we are offering. Statements in this prospectus concerning any document we filed as an exhibit to the registration statement or that we otherwise filed with the SEC are not intended to be comprehensive and are qualified by reference to these filings. You should review the complete document to evaluate these statements. You can obtain a copy of the registration statement from the SEC at the address listed above or from the SEC’s website.

INCORPORATION BY REFERENCE

The SEC allows us to incorporate by reference in this prospectus much of the information we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference in this prospectus is considered to be part of this prospectus. Because we are incorporating by reference future filings with the SEC, this prospectus is continually updated and those future filings may modify or supersede some of the information included or incorporated in this prospectus. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus or in any document previously incorporated by reference have been modified or superseded. This prospectus incorporates by reference the documents listed below (File No. 001-38810) and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, or the Exchange Act (in each case, other than those documents or the portions of those documents not deemed to be filed) and, to the extent designated therein, reports on Form 6-K that we furnish to the SEC, in each case, between the date of the initial registration statement and the effectiveness of the registration statement and following the effectiveness of the registration statement until the offering of the securities under the registration statement is terminated or completed:

• Annual Report on Form 20-F for the fiscal year ended December 31, 2019, filed with the SEC on April 1, 2020; and

• The description of our ordinary shares and ADSs contained in our registration statement on Form 8-A, filed with the SEC under the Exchange Act on February 12, 2019, including any amendment or report filed for the purpose of updating such description.

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address or telephone number:

c/o Stealth BioTherapeutics Inc.

275 Grove Street, Suite 3-107

Newton, MA 02466

(617) 600-6888

3

FORWARD-LOOKING STATEMENTS

This prospectus and the information incorporated by reference in this prospectus include “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Exchange Act. All statements contained or incorporated by reference herein, including statements regarding our strategy, future operations, future financial position, future revenue, projected costs, prospects, plans, objectives of management and expected market growth, other than statements of historical facts, are forward-looking statements. The words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “potential,” “will,” “would,” “could,” “should,” “continue” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. You are cautioned that these forward-looking statements are only predictions and are subject to risks, uncertainties and assumptions that are referenced in the section of any accompanying prospectus supplement entitled “Risk Factors.” You should also carefully review the risk factors and cautionary statements described in the other documents we file from time to time with the SEC, specifically our most recent Annual Report on Form 20-F and our Reports on Form 6-K. We undertake no obligation to revise or update any forward-looking statements, except to the extent required by law.

4

THE COMPANY

We are a clinical-stage biotechnology company focused on the discovery, development and commercialization of novel therapies for diseases involving mitochondrial dysfunction. Mitochondria, found in nearly every cell in the body, are the body’s main source of energy production and are critical for normal organ function. Dysfunctional mitochondria characterize a number of rare genetic diseases and many common age-related diseases, leading to devastating cardiac, ophthalmic and neurological symptoms. We believe our product candidates have significant potential to treat the cardiac, ophthalmic and neurological symptoms of both rare genetic and common age-related mitochondrial diseases. Our mission is to be the leader in mitochondrial medicine, and we have assembled a highly experienced management team, board of directors and group of scientific advisors to help us achieve this mission. Our leadership team has decades of experience leading drug discovery and development programs, including at GlaxoSmithKline, Novo Nordisk, Lilly and Sanofi Genzyme.

Our first clinical product candidate, elamipretide, is a small peptide that targets and binds reversibly to cardiolipin, an essential structural element of mitochondria, stabilizing it under conditions of oxidative stress. This novel mechanism of action has shown potential clinical benefit in both rare genetic and common age-related cardiac and ophthalmic diseases entailing mitochondrial dysfunction. We have exclusive worldwide rights to elamipretide and SBT-20, both of which we licensed from Cornell and Institut de recherches cliniques de Montréal, in 2006.

Our second clinical product candidate, SBT-272, is a novel peptidomimetic that has been shown to increase adenosine triphosphate production and decrease levels of reactive oxygen species in dysfunctional mitochondria in preclinical studies. We have discovered and own over 100 compounds, including SBT-272, SBT-259, and the SBT-550 family, that also target the mitochondria and form the basis of our broad proprietary pipeline of mitochondria-targeted product candidates. We are evaluating compounds in the SBT-259 family, including SBT-20 and SBT-259, as well as compounds in the SBT-550 family, for rare neurological indications. In addition, our internal discovery platform has generated a library of over 100 differentiated proprietary compounds which could have clinical benefit for diseases related to mitochondrial dysfunction and from which we plan to designate potential product candidates. We may also utilize certain of these compounds as part of our carrier platform, in which they could potentially serve as scaffolds to deliver other beneficial compounds to the mitochondria.

Our registered office is located at c/o Intertrust Corporate Services (Cayman) Limited, 190 Elgin Avenue, George Town, Grand Cayman, KY1-9005 Cayman Islands. Our agent for service of process in the United States is Stealth BioTherapeutics Inc., or Stealth Delaware, and the executive offices of Stealth Delaware are located at 275 Grove Street, Suite 3-107, Newton, MA 02466, and the telephone number there is (617) 600-6888.

5

CAPITALIZATION AND INDEBTEDNESS

We intend to include information about our capitalization and indebtedness in prospectus supplements.

6

USE OF PROCEEDS

We intend to use the net proceeds from the sale of any securities offered under this prospectus for general corporate purposes unless otherwise indicated in the applicable prospectus supplement. General corporate purposes may include development of our clinical, preclinical and discovery programs, other research and development costs, acquisition of companies or businesses, repayment and refinancing of debt, working capital and capital expenditures. We may temporarily invest the net proceeds from the sale of any securities offered under this prospectus in a variety of capital preservation instruments, including term deposits and short-term, investment-grade, interest-bearing instruments, until they are used for their stated purpose. We have not determined the amount of net proceeds to be used specifically for such purposes. As a result, management will retain broad discretion over the allocation of net proceeds.

7

DESCRIPTION OF SHARE CAPITAL AND ARTICLES OF ASSOCIATION

The following describes our issued share capital, summarizes the material provisions of our Articles of Association and highlights certain differences in corporate law in the Cayman Islands and the United States. The description of our Articles of Association is based upon, and is qualified by reference to, our Articles of Association. This summary is not complete. You should read our Articles of Association, which are filed as an exhibit to the registration statement of which this prospectus forms a part, for the provisions that are important to you.

General

We were incorporated in April 2006 under the name of Stealth Peptides International Inc as an exempted company incorporated with limited liability under the laws of the Cayman Islands, and we changed our name in June 2015 to Stealth BioTherapeutics Corp. Our affairs are governed by our Articles of Association, the Companies Law and the common law of the Cayman Islands. The objects for which we are established are unrestricted and, pursuant to our Articles of Association, we have full power and authority to carry out any object not prohibited by any law as provided by Section 7(4) of the Companies Law. The following description of our share capital and provisions of our Articles of Association are summaries and are qualified by reference to the Articles of Association that will be in effect upon the closing of this offering. We have filed copies of these documents as exhibits to our registration statement of which this prospectus forms a part.

Issued Share Capital

Our authorized share capital is $360,000 divided into 1,200,000,000 ordinary shares.

As of December 31, 2019 and March 31, 2020, there were 436,720,810 ordinary shares outstanding, par value $0.0003 per share.

Articles of Association

Subject to other provisions in our Articles of Association, our shareholders may by ordinary resolution increase our authorized share capital or by special resolution reduce the share capital and amend our Articles of Association.

General

All of our outstanding ordinary shares are fully paid and non-assessable. No share certificates will be issued in connection with the offering.

The ordinary shares issued upon the completion of the offering are not entitled to any preemptive conversion or redemption rights at the sole option of the holder of ordinary shares. Our shareholders may freely hold and vote their shares (subject to certain restrictions contained in our Articles of Association, such as the process for validly appointing a proxy).

Our board of directors may provide for other classes of shares, including classes of preferred shares, out of our authorized but unissued share capital, which could be utilized for a variety of corporate purposes, including future offerings to raise capital for corporate purposes or for use in employee benefit plans. Such additional classes of shares shall have such rights, restrictions, preferences, privileges and payment obligations as determined by our board of directors. If we issue any preferred shares, the rights, preferences and privileges of holders of our ordinary shares will be subject to, and may be adversely affected by, the rights of the holders of such preferred shares. See “—Variation of Rights of Shares.”

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Repurchase Rights

Any repurchase of our own shares by us as may be agreed with the relevant shareholders shall be approved by our board of directors in compliance with the Companies Law and our Articles of Association, and we may make a payment in respect of such repurchase in any manner authorized by the Companies Law and our Articles of Association, including out of our capital. A payment out of capital by a Cayman Islands company is not lawful unless immediately following the date on which the payment out of capital is proposed to be made the company shall be able to pay its debts as they fall due in the ordinary course of business. Only shares that are fully paid may be repurchased, and there must be at least one share remaining in issue following the repurchase.

Voting Rights

Voting at any meeting of shareholders is by a poll. Each ordinary share is entitled to one vote.

A quorum required for a meeting of shareholders consists of at least one or more of shareholders present in person or by proxy and entitled to vote representing the holders of at least a majority of all of our issued voting share capital.

Shareholders’ meetings are held annually and may otherwise be convened by our board of directors on its own initiative, with at least 10 days’ advance notice to the shareholders. Shareholders’ meetings shall also be convened on the requisition in writing of any shareholder or shareholders holding at least a majority of the issued voting share capital, subject to certain procedural requirements. Advance notice of at least 21 days is required for convening extraordinary general meetings.

Any ordinary resolution to be made by our shareholders requires the affirmative vote of a simple majority of the votes attaching to the ordinary shares cast in person or by proxy at a meeting of our shareholders. A special resolution requires the affirmative vote of not less than two-thirds of the votes cast in person or by proxy at a meeting of our shareholders. A special resolution is required for certain matters specified in the Companies Law as requiring approval by special resolution, including, without limitation, amending our Articles of Association, reducing our authorized share capital, changing our name and appointing a voluntary liquidator.

An ordinary resolution or a special resolution may also be adopted by way of unanimous written resolution signed by or on behalf of each shareholder who would have been entitled to vote on such matter at a general meeting without a meeting being held.

Dividends

With the exception of section 34 of the Companies Law, there are no statutory provisions relating to the payment of dividends in the Cayman Islands. Based upon English case law, which is regarded as persuasive in the Cayman Islands, dividends may be paid only out of profits. Section 34 of the Companies Law permits, subject to a solvency test and the provisions, if any, of the company’s memorandum and articles of association, the payment of dividends and distributions out of the share premium account.

Any dividends will be paid to the custodian of the ADSs being issued in this offering and shall be subject to further distribution to you as a beneficial owner of the underlying ordinary shares by the custodian. See “Description of American Depositary Shares—Dividends and Other Distributions.”

Liquidation

On a return of capital on winding up or otherwise (other than on conversion, redemption or purchase of ordinary shares), assets available for distribution among the holders of ordinary shares shall be distributed among the holders of the ordinary shares on a pro rata basis.

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Transfer of Shares

Subject to the restrictions of our Articles of Association and the Nasdaq Listing Rules or any relevant securities law, any of our shareholders may transfer all or any of his or her ordinary shares by an instrument of transfer in the usual or common form prescribed by Nasdaq or any other form approved by our board of directors.

Subject to the Nasdaq Listing Rules and any rights or restrictions for time being attached to any share, our board of directors may in their absolute discretion decline to register any transfer of shares.

Subject to our Articles of Association and the Nasdaq Listing Rules and any rights or restrictions for time being attached to any share, the registration of transfers of shares may be suspended and our register of members closed at such times and for such periods as our board of directors may from time to time determine.

Variation of Rights of Shares

The rights attached to any class of shares may, subject to any rights or restrictions attached to any class, be materially adversely varied or abrogated only with written consent of the holders of not less than two-thirds of the issued shares of the relevant class or with the sanction of a resolution passed at a separate meeting of the holders of the shares of such class by a majority of two-thirds of the votes cast at such a meeting.

The rights conferred upon the shareholders of any class (including, without limitation and for the avoidance of doubt, the ordinary shares) shall not, subject to any rights or restrictions attached to the shares of that class, be deemed to be materially adversely varied or abrogated by, among other things, the creation, allotment or issuance of further shares ranking pari passu with or subsequent to such class or the redemption or purchase of any shares of any class by us.

Inspection of Books and Records

Holders of our ordinary shares have no general right under the Companies Law to inspect or obtain copies of our register of members or our corporate records other than our Articles of Association or our register of mortgages and charges.

The Registrar of Companies in the Cayman Islands, referred to as the Registrar of Companies, shall make available the list of the names of the current directors of a Cayman Islands company and, where applicable, the current alternate directors of a Cayman Islands company for inspection by any person, on payment of the fee required under the Companies Law for each inspection and subject to such conditions as the Registrar of Companies may impose.

Borrowing Power

Our board of directors may exercise all powers to borrow money and to mortgage or charge our undertaking, property and uncalled capital, to provide for a security interest to be taken in such undertaking, property or uncalled capital, to issue debentures, debenture stock and other securities whenever money is borrowed or as security for any debt, liability or obligation of us or of any third party.

Share Options

As of December 31, 2019, options to purchase 36,126,371 ordinary shares at a weighted-average exercise price of $0.99 per share were outstanding, of which options to purchase 15,869,209 ordinary shares were exercisable, at a weighted-average exercise price of $0.99 per share. The options lapse after ten years from the date of grant.

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Warrants

In June 2017, we issued a warrant to Hercules, which is exercisable for 500,000 ordinary shares at an exercise price of $1.00 per share. The warrant expires in June 2027.

Differences in Corporate Law

	DELAWARE	CAYMAN ISLANDS
Title of Organizational Documents	Certificate of Incorporation and Bylaws	Memorandum and Articles of Association
Duties of Directors	Under Delaware law, the business and affairs of a corporation are managed by or under the direction of its board of directors. In exercising their powers, directors are charged with a fiduciary duty of care to protect the interests of the corporation and a fiduciary duty of loyalty to act in the best interests of its shareholders. The duty of care requires that directors act in an informed and deliberative manner and inform themselves, prior to making a business decision, of all material information reasonably available to them. The duty of care also requires that directors exercise care in overseeing and investigating the conduct of the corporation’s employees. The duty of loyalty may be summarized as the duty to act in good faith, not out of self-interest, and in a manner which the director reasonably believes to be in the best interests of the shareholders.	As a matter of Cayman Islands law, directors of Cayman Islands companies owe fiduciary duties to the company which include, amongst other things, a duty to act in good faith in their dealings with or on behalf of the company and exercise their powers and fulfill the duties of their office honestly. Five core duties are: •  a duty to act in good faith in what the directors bona fide consider to be the best interests of the company (and in this regard, it should be noted that the duty is owed to the company and not to associate companies, subsidiaries or holding companies); •  a duty not to personally profit from opportunities that arise from the office of director (unless the company permits him to do so); •  a duty of trusteeship of the company’s assets; •  a duty to avoid conflicts of interest; and •  a duty to exercise powers for the purpose for which such powers were conferred.

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	DELAWARE	CAYMAN ISLANDS
		A director of a Cayman Islands company also owes the company a duty to act with skill, care and diligence. A director need not exhibit in the performance of his or her duties a greater degree of skill than may reasonably be expected from a person of his or her knowledge and experience.
Limitations on Personal Liability of Directors	Subject to the limitations described below, a certificate of incorporation may provide for the elimination or limitation of the personal liability of a director to the corporation or its shareholders for monetary damages for a breach of fiduciary duty as a director. Such provision cannot limit liability for breach of loyalty, acts or omissions not in good faith, intentional misconduct, unlawful payment of dividends or unlawful share purchase or redemption. In addition, the certificate of incorporation cannot limit liability for any act or omission occurring prior to the date when such provision becomes effective.	The Companies Law has no equivalent provision to Delaware law regarding the limitation of director’s liability. However, as a matter of public policy, Cayman Islands law will not allow the limitation of a director’s liability to the extent that the liability is a consequence of the director committing a crime or of the director’s own fraud, dishonesty or willful default.
Indemnification of Directors, Officers, Agents, and Others	A corporation has the power to indemnify any director, officer, employee or agent of the corporation who was, is or is threatened to be made a party who acted in good faith and in a manner they believed to be in the best interests of the corporation, and if with respect to a criminal proceeding, had no reasonable cause to believe his conduct would be unlawful, against amounts actually and reasonably incurred.	Cayman Islands law does not limit the extent to which a company’s articles of association may provide for indemnification of directors and officers, except to the extent any such provision may be held by the Cayman Islands Court to be contrary to public policy, such as to provide indemnification against the consequences of committing a crime, or against the indemnified person’s own fraud, dishonesty or willful default.
Interested Directors	Under Delaware law, a transaction in which a director who has an interest is not void or voidable solely because such interested director is present at or participates in the meeting that authorizes the transaction if: (i) the material facts	Under our Articles of Association, directors who are in any way, whether directly or indirectly, interested in a contract or proposed contract with our company must declare the nature of their interest at a meeting of the board of directors.

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	DELAWARE	CAYMAN ISLANDS
	as to such interested director’s relationship or interests are disclosed or are known to the board of directors and the board in good faith authorizes the transaction by the affirmative vote of a majority of the disinterested directors, even though the disinterested directors are less than a quorum; (ii) such material facts are disclosed or are known to	Following such declaration, a director may vote in respect of any contract or proposed contract notwithstanding his interest; provided that, in exercising any such vote, such director’s duties remain as described above.
	the shareholders entitled to vote on such transaction and the transaction is specifically approved in good faith by vote of the shareholders; or (iii) the transaction is fair as to the corporation as of the time it is authorized, approved or ratified. Under Delaware law, a director could be held liable for any transaction in which such director derived an improper personal benefit.
Voting Requirements	The certificate of incorporation may include a provision requiring supermajority approval by the directors or shareholders for any corporate action. In addition, under Delaware law, certain business combinations involving interested shareholders require approval by a supermajority of the non-interested shareholders.	As a matter of Cayman Islands law, certain matters must be approved by special resolution of the shareholders, including amending or adopting memorandum or articles of association of a Cayman Islands company, appointment of inspectors to examine company affairs, reduction of share capital (subject, in relevant circumstances, to court approval), change of name, authorization of a plan of merger or transfer by way of continuation to another jurisdiction or consolidation, voluntary winding up of the company or the recalling of the liquidation of the company. The Companies Law requires that a special resolution be passed by a majority of at least two-thirds or such higher percentage as set forth in the articles of association, of shareholders being entitled to vote and do vote in person or by proxy at a general meeting, or by unanimous written consent of shareholders

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	DELAWARE	CAYMAN ISLANDS
		entitled to vote at a general meeting. Our Articles of Association does not provide for a higher threshold. The Companies Law defines “special resolutions” only. A company’s articles of association can therefore tailor the definition of “ordinary resolutions” as a whole, or with respect to specific provisions. Our Articles of Association provide that an ordinary resolution is a resolution (i) passed by a simple majority of such shareholders as, being entitled to do so, vote in person (or, where proxies are allowed, by proxy) at a general meeting and regard shall be had in computing a majority to the number of votes to which each shareholder is entitled or (ii) approved in writing by all of the shareholders entitled to vote at a general meeting in one or more instruments each signed by one or more of the shareholders and the effective date of the resolution so adopted shall be the date on which the instrument (or the last of such instruments, if more than one) is executed.
Voting for Directors	Under Delaware law, unless otherwise specified in the certificate of incorporation or bylaws of the corporation, directors shall be elected by a plurality of the votes of the shares present in person or represented by proxy at the meeting and entitled to vote on the election of directors.	Our Articles of Association provide that at an annual general meeting where a resolution for the election of directors is proposed in accordance with our Articles of Association, a plurality of the votes cast shall be sufficient to elect a director.
Cumulative Voting	No cumulative voting for the election of directors unless so provided in the certificate of incorporation.	No cumulative voting for the election of directors unless so provided in the articles of association. Our Articles of Association do not provide for cumulative voting on the election of the directors as described above.

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	DELAWARE	CAYMAN ISLANDS
Directors’ Powers Regarding Bylaws	The certificate of incorporation may grant the directors the power to adopt, amend or repeal bylaws.	Our Articles of Association may only be amended by a special resolution of the shareholders.
Nomination and Removal of Directors and Filling Vacancies on Board	Shareholders may generally nominate directors if they comply with advance notice provisions and other procedural requirements in company bylaws. Holders of a majority of the shares may remove a director with or without cause, except in certain cases involving a classified board or if the company uses cumulative voting. Unless otherwise provided for in the certificate of incorporation or bylaws, directorship vacancies are filled by a majority of the directors elected or then in office.	Nomination and removal of directors and filling of board vacancies are governed by the terms of the articles of association. Our Articles of Association provide that a director shall hold office until such time they resign upon the expiry of a full term of three years, if they are removed from office by ordinary resolution of the shareholders or otherwise in accordance with our Articles of Association.
Mergers and Similar Arrangements	Under Delaware law, with certain exceptions, a merger, consolidation, exchange or sale of all or substantially all the assets of a corporation must be approved by the board of directors and a majority of the outstanding shares entitled to vote thereon. Under Delaware law, a shareholder of a corporation participating in certain major corporate transactions may, under certain circumstances, be entitled to appraisal rights pursuant to which such shareholder may receive cash in the amount of the fair value of the shares held by such shareholder (as determined by a court) in lieu of the consideration such shareholder would otherwise receive in the transaction. Delaware law also provides that a parent corporation, by resolution of its board of directors, may merge with any subsidiary, of which it owns at least 90% of each class of capital stock without a vote by shareholders of such subsidiary. Upon any such merger, dissenting shareholders of the subsidiary would have appraisal rights.	The Companies Law provides for the merger or consolidation of two or more companies into a single entity. The legislation makes a distinction between a “consolidation” and a “merger.” In a consolidation, a new entity is formed from the combination of each participating company, and the separate consolidating parties, as a consequence, cease to exist and are each stricken by the Registrar of Companies. In a merger, one company remains as the surviving entity, having in effect absorbed the other merging parties that then cease to exist. Two or more Cayman Islands-registered companies may merge or consolidate. Cayman Islands-registered companies may also merge or consolidate with overseas companies provided that the laws of the foreign jurisdiction permit such merger or consolidation. A plan of merger or consolidation shall be authorized by each constituent company by way of (i) a special resolution of the members of each such constituent company and

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DELAWARE

CAYMAN ISLANDS

(ii) such other authorization, if any, as may be specified in such constituent company’s articles of association. If one of the constituent companies is an overseas company, a declaration from a director of the overseas company is required to confirm that the merger or consolidation is permitted or not prohibited by the constituent overseas company and by the laws of the jurisdiction in which the overseas company is existing, and that those constitutional documents have been or will be complied with. Shareholder approval is not required where a parent company registered in the Cayman Islands seeks to merge with one or more of its subsidiaries registered in the Cayman Islands and a copy of the plan of merger is given to every member of each subsidiary company to be merged unless that member agrees otherwise. Secured creditors must consent to the merger although application can be made to the Cayman Islands Court for such requirement to be waived if such secured creditor does not grant its consent to the merger. Where an overseas company wishes to merge with a Cayman Islands company, consent or approval to the transfer of any security interest granted by the overseas company to the resulting Cayman Islands entity in the transaction is required, unless otherwise released or waived by the secured party. If the merger plan is approved, it is then filed with the Cayman Islands General Registry along with a declaration by a director of each company. The Registrar of Companies will then issue a certificate of merger which shall be prima facie evidence of compliance with all requirements of the Companies Law in respect of the merger or consolidation.

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DELAWARE

CAYMAN ISLANDS

The surviving or consolidated entity remains or becomes active while the other company or companies are automatically dissolved. Unless the shares of such shareholder are publicly listed or quoted, dissenting shareholders in a merger or consolidation of this type are entitled to payment of the fair value of their shares if such shareholder provides a written objection before the vote on such merger or consolidation. With respect to shares that are listed or quoted, a shareholder shall have similar rights only if it is required by the terms of the merger or consolidation to accept for such shares property other than: (i) shares (or depositary receipts in respect thereof) in the surviving or consolidated company; (ii) listed or quoted shares (or depositary receipts in respect thereof) of another company; (iii) cash in lieu of any fractions of shares or depositary receipts described at (i) and (ii); or (iv) any combination of shares, depositary receipts or cash described in (i)-(iii). Cayman Islands companies may also be restructured or amalgamated under supervision of the Cayman Islands Court by way of a court-sanctioned “scheme of arrangement.” A scheme of arrangement is one of several transactional mechanisms available in the Cayman Islands for achieving a restructuring. Others include share capital exchange, merger (as described above), asset acquisition or control, through contractual arrangements, of an operating business. A Cayman Islands Court scheme of arrangement requires the approval of a majority in number, of each class of shareholders and creditors with whom the arrangement is to be made and who

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DELAWARE	CAYMAN ISLANDS
	must in addition represent three-fourths in value of each such class of shareholders or creditors, as the case may be, that are present and voting either in person or by proxy at the meeting summoned for that purpose. The convening of the meetings and subsequently the terms of the arrangement must be sanctioned by the Cayman Islands Court. While a dissenting shareholder would have the right to express to the Cayman Islands Court its view that the transaction ought not be approved, the Cayman Islands Court can
	be expected to approve the scheme of arrangement if it is satisfied that: •  the classes which are required to approve the scheme of arrangement have been properly constituted, so that the members of such classes are properly represented; •  the meetings held by the company in relation to the approval of the scheme of arrangement by such classes have been convened and held in accordance with any directions given by the Cayman Islands Court; •  the scheme of arrangement has been properly explained to the shareholders or creditors so that they have been able to exercise an informed vote in respect of the scheme; the scheme of arrangement is one which an intelligent and honest man, who is a member of the relevant class and properly acting, might approve. When a takeover offer is made and accepted by holders of 90% of the shares within four months, the offeror may, within a two-month

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	DELAWARE	CAYMAN ISLANDS
		period following the expiration of the said four month period, require the holders of the remaining shares to transfer such shares on the terms of the offer. An objection may be made to the Cayman Islands Court but is unlikely to succeed unless there is evidence of fraud, bad faith or collusion. If the arrangement and reconstruction are thus approved, any dissenting shareholders would have no rights comparable to appraisal rights, which would otherwise ordinarily be available to dissenting shareholders of U.S. corporations, providing rights to receive payment in cash for the judicially determined value of the shares. Our Articles of Association provide that we may by special resolution resolve to merge or consolidate in accordance with the Companies Law.
Shareholder Suits	Class actions and derivative actions generally are available to shareholders under Delaware law for, among other things, breach of fiduciary duty, corporate waste and actions not taken in accordance with applicable law. In such actions, the court generally has discretion to permit the winning party to recover attorneys’ fees incurred in connection with such action.	The rights of shareholders under Cayman Islands law are not as extensive as those under Delaware law. Class actions are generally not available to shareholders under Cayman Islands laws; historically, there have not been any reported instances of such class actions having been successfully brought before the Cayman Islands Court. In principle, we will normally be the proper plaintiff and a derivative action may be brought by a minority shareholder in only limited circumstances. In this regard, the Cayman Islands Court would ordinarily be expected to follow English case law precedent, which would permit a shareholder to commence an action in the company’s name to remedy a wrong done to the company where the act complained of cannot be ratified by the shareholders and where control of the company by the wrongdoer results in the company not pursuing

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	DELAWARE	CAYMAN ISLANDS
		a remedy itself. The case law shows that derivative actions have been permitted in respect of acts that are beyond the company’s corporate power, illegal, where the individual rights of the plaintiff shareholder have been infringed or are about to be infringed and acts that are alleged to constitute a “fraud on the minority.” The winning party in such an action generally would be able to recover a portion of attorney’s fees incurred in connection with such action.
Inspection of Corporate Records	Under Delaware law, shareholders of a Delaware corporation have the right during normal business hours to inspect for any proper purpose, and to obtain copies of list(s) of shareholders and other books and records of the corporation and its subsidiaries, if any, to the extent the books and records of such subsidiaries are available to the corporation.	Shareholders of a Cayman Islands exempted company have no general right under Cayman Islands law to inspect or obtain copies of the register of members or other corporate records (other than the register of mortgages or charges) of the company. However, these rights may be provided in the company’s articles of association. Our Articles of Association provide that the holders of our ordinary shares will have no general right to inspect or obtain copies of our register of members or our corporate records other than our Articles of Association. The Registrar of Companies shall make available the list of the names of the current directors of a Cayman Islands company and, where applicable, the current alternate directors of a Cayman Islands company for inspection by any person, on payment of the fee required under the Companies Law for each inspection and subject to such conditions as the Registrar of Companies may impose.
Shareholder Proposals	Unless provided in the corporation’s certificate of incorporation or bylaws, Delaware law does not include a provision restricting the manner in which	The Companies Law does not provide shareholders any right to bring business before a meeting or requisition a general meeting. However, these rights may be

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	DELAWARE	CAYMAN ISLANDS
	shareholders may bring business before a meeting.	provided in the company’s articles of association.
		Our Articles of Association provide for extraordinary general meeting to be convened on the requisition in writing of any shareholder(s) entitled to attend and vote at our extraordinary general meetings and to exercise at least a majority of the votes permitted to be exercised at any such meeting subject to certain procedural requirements.
Approval of Corporate Matters by Written Consent	Delaware law permits shareholders to take action by written consent signed by the holders of outstanding shares having not less than the minimum number of votes that would be necessary to authorize or take such action at a meeting of shareholders.	The Companies Law allows a special resolution to be passed in writing only if signed by all the voting shareholders (if authorized by the articles of association).
Calling of Special Shareholders Meetings	Delaware law permits the board of directors or any person who is authorized under a corporation’s certificate of incorporation or bylaws to call a special meeting of shareholders.	The Companies Law does not have provisions governing the proceedings of shareholders meetings which are usually provided in the articles of association. Our Articles of Association provide for an extraordinary general meeting to be convened on the requisition in writing of any shareholder(s) entitled to attend and vote at our extraordinary general meetings and to exercise at least a majority of the votes permitted to be exercised at any such meeting subject to certain procedural requirements.

Listing on The Nasdaq Global Market

Our ADSs are listed on The Nasdaq Global Market under the trading symbol “MITO.”

Registrar

Our register of members, or share register, reflects only record owners of our ordinary shares. Holders of our ADSs are not treated as one of our shareholders and their names will therefore not be entered in our share register. The depositary, the custodian or their nominees will be the holder of the shares underlying our ADSs. For further discussion on our ADSs and ADS holder rights, see “Description of American Depositary Shares” in this prospectus.

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DESCRIPTION OF AMERICAN DEPOSITARY SHARES

Description of American Depositary Shares

Citibank, N.A., or Citibank, is acting as the depositary for the American Depositary Shares, or ADSs. Citibank’s depositary offices are located at 388 Greenwich Street, New York, New York 10013. ADSs represent ownership interests in securities that are on deposit with the depositary. ADSs may be represented by certificates that are commonly known as American Depositary Receipts, or ADRs. The depositary typically appoints a custodian to safekeep the securities on deposit. In this case, the custodian is Citibank, N.A.—Hong Kong, located at 9/F, Citi Tower, One Bay East, 83 Hoi Bun Road, Kwun Tong, Kowloon, Hong Kong.

We have appointed Citibank as depositary pursuant to a deposit agreement. A copy of the deposit agreement is on file with the SEC under cover of a report on Form 6-K. You may obtain a copy of the deposit agreement from the SEC’s website (www.sec.gov). Please refer to File No. 001-38810 when retrieving such copy.

We are providing you with a summary description of the material terms of the ADSs and of your material rights as an owner of ADSs. Please note that summaries by their nature lack the precision of the information summarized and the rights and obligations of an owner of ADSs will be determined by reference to the terms of the deposit agreement and not by this summary. We urge you to review the deposit agreement in its entirety. The portions of this summary that are italicized describe matters that may be relevant to ownership of ADSs but may not be contained in the deposit agreement.

Each ADS represents the right to receive, and to exercise the beneficial ownership interests in, 12 ordinary shares that are on deposit with the depositary and/or custodian. An ADS also represents the right to receive, and to exercise the beneficial interests in, any other property received by the depositary or the custodian on behalf of the owner of the ADS but that has not been distributed to the owners of ADSs because of legal restrictions or practical considerations. We and the depositary may agree to change the ADS-to-ordinary shares ratio by amending the deposit agreement. This amendment may give rise to, or change, the depositary fees payable by ADS owners. The custodian, the depositary and their respective nominees will hold all deposited property for the benefit of the holders and beneficial owners of ADSs. The deposited property does not constitute the proprietary assets of the depositary, the custodian or their nominees. Beneficial ownership in the deposited property will under the terms of the deposit agreement be vested in the beneficial owners of the ADSs. The depositary, the custodian and their respective nominees will be the record holders of the deposited property represented by the ADSs for the benefit of the holders and beneficial owners of the corresponding ADSs. A beneficial owner of ADSs may or may not be the holder of ADSs. Beneficial owners of ADSs will be able to receive, and to exercise beneficial ownership interests in, the deposited property only through the registered holders of the ADSs, the registered holders of the ADSs (on behalf of the applicable ADS owners) only through the depositary, and the depositary (on behalf of the owners of the corresponding ADSs) directly, or indirectly, through the custodian or their respective nominees, in each case upon the terms of the deposit agreement.

If you become an owner of ADSs, you will become a party to the deposit agreement and therefore will be bound to its terms and to the terms of any ADR that represents your ADSs. The deposit agreement and the ADR specify our rights and obligations as well as your rights and obligations as owner of ADSs and those of the depositary. As an ADS holder you appoint the depositary to act on your behalf in certain circumstances. The deposit agreement and the ADRs are governed by New York law. However, our obligations to the holders of ordinary shares will continue to be governed by the laws of the Cayman Islands, which may be different from the laws of the United States.

In addition, applicable laws and regulations may require you to satisfy reporting requirements and obtain regulatory approvals in certain circumstances. You are solely responsible for complying with such reporting requirements and obtaining such approvals. Neither the depositary, the custodian, us or any of their or our respective agents or affiliates shall be required to take any actions whatsoever on your behalf to satisfy such reporting requirements or obtain such regulatory approvals under applicable laws and regulations.

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As an owner of ADSs, we will not treat you as one of our shareholders and you will not have direct shareholder rights. The depositary will hold on your behalf the shareholder rights attached to the ordinary shares underlying your ADSs.

As an owner of ADSs you will be able to exercise the shareholders rights for the ordinary shares represented by your ADSs through the depositary only to the extent contemplated in the deposit agreement. To exercise any shareholder rights not contemplated in the deposit agreement you will, as an ADS owner, need to arrange for the cancellation of your ADSs and become a direct shareholder.

The manner in which you own the ADSs (e.g., in a brokerage account vs. as registered holder, or as holder of certificated vs. uncertified ADSs) may affect your rights and obligations, and the manner in which, and extent to which, the depositary’s services are made available to you. As an owner of ADSs, you may hold your ADSs either by means of an ADR registered in your name, through a brokerage or safekeeping account, or through an account established by the depositary in your name reflecting the registration of uncertificated ADSs directly on the books of the depositary (commonly referred to as the direct registration system or DRS). The direct registration system reflects the uncertificated (book-entry) registration of ownership of ADSs by the depositary. Under the direct registration system, ownership of ADSs is evidenced by periodic statements issued by the depositary to the holders of the ADSs. The direct registration system includes automated transfers between the depositary and The Depository Trust Company, or DTC, the central book-entry clearing and settlement system for equity securities in the United States. If you decide to hold your ADSs through your brokerage or safekeeping account, you must rely on the procedures of your broker or bank to assert your rights as ADS owner. Banks and brokers typically hold securities such as the ADSs through clearing and settlement systems such as DTC. The procedures of such clearing and settlement systems may limit your ability to exercise your rights as an owner of ADSs. Please consult with your broker or bank if you have any questions concerning these limitations and procedures. All ADSs held through DTC will be registered in the name of a nominee of DTC. This summary description assumes you have opted to own the ADSs directly by means of an ADS registered in your name and, as such, we will refer to you as the “holder.” When we refer to “you,” we assume the reader owns ADSs and will own ADSs at the relevant time.

The registration of the ordinary shares in the name of the depositary or the custodian shall, to the maximum extent permitted by applicable law, vest in the depositary or the custodian the record ownership in the applicable ordinary shares with the beneficial ownership rights and interests in such ordinary shares being at all times vested with the beneficial owners of the ADSs representing the ordinary shares. The depositary or the custodian shall at all times be entitled to exercise the beneficial ownership rights in all deposited property, in each case only on behalf of the holders and beneficial owners of the ADSs representing the deposited property.

Dividends and Distributions

As a holder of ADSs, you generally have the right to receive the distributions we make on the securities deposited with the custodian. Your receipt of these distributions may be limited, however, by practical considerations and legal limitations. Holders of ADSs will receive such distributions under the terms of the deposit agreement in proportion to the number of ADSs held as of the specified record date, after deduction of the applicable fees, taxes and expenses.

Distributions of Cash

Whenever we make a cash distribution for the securities on deposit with the custodian, we will deposit the funds with the custodian. Upon receipt of confirmation of the deposit of the requisite funds, the depositary will arrange for the funds received in a currency other than U.S. dollars to be converted into U.S. dollars and for the distribution of the U.S. dollars to the holders, subject to the laws and regulations of the Cayman Islands.

The conversion into U.S. dollars will take place only if practicable and if the U.S. dollars are transferable to the United States. The depositary will apply the same method for distributing the proceeds of the sale of any property (such as undistributed rights) held by the custodian in respect of securities on deposit.

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The distribution of cash will be made net of the fees, expenses, taxes and governmental charges payable by holders under the terms of the deposit agreement. The depositary will hold any cash amounts it is unable to distribute in a non-interest bearing account for the benefit of the applicable holders and beneficial owners of ADSs until the distribution can be effected or the funds that the depositary holds must be escheated as unclaimed property in accordance with the laws of the relevant states of the United States.

Distributions of Shares

Whenever we make a free distribution of ordinary shares for the securities on deposit with the custodian, we will deposit the applicable number of ordinary shares with the custodian. Upon receipt of confirmation of such deposit, the depositary will either distribute to holders new ADSs representing the ordinary shares deposited or modify the ADS-to-ordinary shares ratio, in which case each ADS you hold will represent rights and interests in the additional ordinary shares so deposited. Only whole new ADSs will be distributed. Fractional entitlements will be sold and the proceeds of such sale will be distributed as in the case of a cash distribution.

The distribution of new ADSs or the modification of the ADS-to-ordinary shares ratio upon a distribution of ordinary shares will be made net of the fees, expenses, taxes and governmental charges payable by holders under the terms of the deposit agreement. In order to pay such taxes or governmental charges, the depositary may sell all or a portion of the new ordinary shares so distributed.

No such distribution of new ADSs will be made if it would violate a law (e.g., the U.S. securities laws) or if it is not operationally practicable. If the depositary does not distribute new ADSs as described above, it may sell the ordinary shares received upon the terms described in the deposit agreement and will distribute the proceeds of the sale as in the case of a distribution of cash.

Distributions of Rights

Whenever we intend to distribute rights to purchase additional ordinary shares, we will give prior notice to the depositary and we will assist the depositary in determining whether it is lawful and reasonably practicable to distribute rights to purchase additional ADSs to holders.

The depositary will establish procedures to distribute rights to purchase additional ADSs to holders and to enable such holders to exercise such rights if it is lawful and reasonably practicable to make the rights available to holders of ADSs, and if we provide all of the documentation contemplated in the deposit agreement (such as opinions to address the lawfulness of the transaction). You may have to pay fees, expenses, taxes and other governmental charges to subscribe for the new ADSs upon the exercise of your rights. The depositary is not obligated to establish procedures to facilitate the distribution and exercise by holders of rights to purchase new ordinary shares other than in the form of ADSs.

The depositary will not distribute the rights to you if:

• we do not timely request that the rights be distributed to you or we request that the rights not be distributed to you; or

• we fail to deliver satisfactory documents to the depositary; or

• it is not reasonably practicable to distribute the rights.

The depositary will sell the rights that are not exercised or not distributed if such sale is lawful and reasonably practicable. The proceeds of such sale will be distributed to holders as in the case of a cash distribution. If the depositary is unable to sell the rights, it will allow the rights to lapse.

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Elective Distributions

Whenever we intend to distribute a dividend payable at the election of shareholders either in cash or in additional shares, we will give prior notice thereof to the depositary and will indicate whether we wish the elective distribution to be made available to you. In such case, we will assist the depositary in determining whether such distribution is lawful and reasonably practicable.

The depositary will make the election available to you only if it is reasonably practicable and if we have provided all of the documentation contemplated in the deposit agreement. In such case, the depositary will establish procedures to enable you to elect to receive either cash or additional ADSs, in each case as described in the deposit agreement.

If the election is not made available to you, you will receive either cash or additional ADSs, depending on what a shareholder in the Cayman Islands would receive upon failing to make an election, as more fully described in the deposit agreement.

Other Distributions

Whenever we intend to distribute property other than cash, ordinary shares or rights to purchase additional ordinary shares, we will notify the depositary in advance and will indicate whether we wish such distribution to be made to you. If so, we will assist the depositary in determining whether such distribution to holders is lawful and reasonably practicable.

If it is reasonably practicable to distribute such property to you and if we provide to the depositary all of the documentation contemplated in the deposit agreement, the depositary will distribute the property to the holders in a manner it deems practicable.

The distribution will be made net of fees, expenses, taxes and governmental charges payable by holders under the terms of the deposit agreement. In order to pay such taxes and governmental charges, the depositary may sell all or a portion of the property received.

The depositary will not distribute the property to you and will sell the property if:

• we do not request that the property be distributed to you or if we ask that the property not be distributed to you; or

• we do not deliver satisfactory documents to the depositary; or

• the depositary determines that all or a portion of the distribution to you is not reasonably practicable.

The proceeds of such a sale will be distributed to holders as in the case of a cash distribution.

Redemption

Whenever we decide to redeem any of the securities on deposit with the custodian, we will notify the depositary in advance. If it is practicable and if we provide all of the documentation contemplated in the deposit agreement, the depositary will provide notice of the redemption to the holders.

The custodian will be instructed to surrender the shares being redeemed against payment of the applicable redemption price. The depositary will convert the redemption funds received into U.S. dollars upon the terms of the deposit agreement and will establish procedures to enable holders to receive the net proceeds from the redemption upon surrender of their ADSs to the depositary. You may have to pay fees, expenses, taxes and other governmental charges upon the redemption of your ADSs. If less than all ADSs are being redeemed, the ADSs to be retired will be selected by lot or on a pro rata basis, as the depositary may determine.

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Changes Affecting Ordinary Shares

The ordinary shares held on deposit for your ADSs may change from time to time. For example, there may be a change in nominal or par value, split-up, cancellation, consolidation or any other reclassification of such ordinary shares or a recapitalization, reorganization, merger, consolidation or sale of assets of the Company.

If any such change were to occur, your ADSs would, to the extent permitted by law, represent the right to receive the property received or exchanged in respect of the ordinary shares held on deposit. The depositary may in such circumstances deliver new ADSs to you, amend the deposit agreement, the ADRs and the applicable Registration Statement(s) on Form F-6, call for the exchange of your existing ADSs for new ADSs and take any other actions that are appropriate to reflect as to the ADSs the change affecting the ordinary shares. If the depositary may not lawfully distribute such property to you, the depositary may sell such property and distribute the net proceeds to you as in the case of a cash distribution.

Issuance of ADSs upon Deposit of Ordinary Shares

Upon completion of this offering, the ordinary shares being offered pursuant to this prospectus will be deposited by us with the custodian. Upon receipt of confirmation of such deposit, the depositary will issue ADSs to the underwriters named in this prospectus.

After the closing of this offering, the depositary may create ADSs on your behalf if you or your broker deposit ordinary shares with the custodian. The depositary will deliver these ADSs to the person you indicate only after you pay any applicable issuance fees and any charges and taxes payable for the transfer of the ordinary shares to the custodian. Your ability to deposit ordinary shares and receive ADSs may be limited by the legal considerations in the United States and Cayman Islands applicable at the time of deposit.

The issuance of ADSs may be delayed until the depositary or the custodian receives confirmation that all required approvals have been given and that the ordinary shares have been duly transferred to the custodian. The depositary will only issue ADSs in whole numbers.

When you make a deposit of ordinary shares, you will be responsible for transferring good and valid title to the depositary. As such, you will be deemed to represent and warrant that:

• the ordinary shares are duly authorized, validly issued, fully paid, non-assessable and legally obtained;

• all preemptive (and similar) rights, if any, with respect to such ordinary shares have been validly waived or exercised;

• you are duly authorized to deposit the ordinary shares;

• the ordinary shares presented for deposit are free and clear of any lien, encumbrance, security interest, charge, mortgage or adverse claim, and are not, and the ADSs issuable upon such deposit will not be, “restricted securities” (as defined in the deposit agreement);

• the ordinary shares presented for deposit have not been stripped of any rights or entitlements; and

• the deposit of the ordinary shares does not violate any applicable provisions of the Cayman Islands.

If any of the representations or warranties are incorrect in any way, we and the depositary may, at your cost and expense, take any and all actions necessary to correct the consequences of the misrepresentations.

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Transfer, Combination and Split Up of ADRs

As an ADR holder, you will be entitled to transfer, combine or split up your ADRs and the ADSs evidenced thereby. For transfers of ADRs, you will have to surrender the ADRs to be transferred to the depositary and also must:

• ensure that the surrendered ADR is properly endorsed or otherwise in proper form for transfer;

• provide such proof of identity and genuineness of signatures as the depositary deems appropriate;

• provide any transfer stamps required by the State of New York or the United States; and

• pay all applicable fees, charges, expenses, taxes and other government charges payable by ADR holders pursuant to the terms of the deposit agreement, upon the transfer of ADRs.

To have your ADRs either combined or split up, you must surrender the ADRs in question to the depositary with your request to have them combined or split up, and you must pay all applicable fees, charges and expenses payable by ADR holders, pursuant to the terms of the deposit agreement, upon a combination or split up of ADRs.

Withdrawal of Ordinary Shares Upon Cancellation of ADSs

As a holder, you will be entitled to present your ADSs to the depositary for cancellation and then receive the corresponding number of underlying ordinary shares at the custodian’s offices. Your ability to withdraw the ordinary shares held in respect of the ADSs may be limited by the legal considerations in the United States and Cayman Islands applicable at the time of withdrawal. In order to withdraw the ordinary shares represented by your ADSs, you will be required to pay to the depositary the fees for cancellation of ADSs and any charges and taxes payable upon the transfer of the ordinary shares. You assume the risk for delivery of all funds and securities upon withdrawal. Once canceled, the ADSs will not have any rights under the deposit agreement.

If you hold ADSs registered in your name, the depositary may ask you to provide proof of identity and genuineness of any signature and such other documents as the depositary may deem appropriate before it will cancel your ADSs. The withdrawal of the ordinary shares represented by your ADSs may be delayed until the depositary receives satisfactory evidence of compliance with all applicable laws and regulations. Please keep in mind that the depositary will only accept ADSs for cancellation that represent a whole number of securities on deposit.

You will have the right to withdraw the securities represented by your ADSs at any time except for:

• temporary delays that may arise because (i) the transfer books for the ordinary shares or ADSs are closed, or (ii) ordinary shares are immobilized on account of a shareholders’ meeting or a payment of dividends;

• obligations to pay fees, taxes and similar charges;

• restrictions imposed because of laws or regulations applicable to ADSs or the withdrawal of securities on deposit; and/or

• other circumstances specifically contemplated by Section I.A.(l) of the General Instructions to Form F-6 (as such General Instructions may be amended from time to time).

The deposit agreement may not be modified to impair your right to withdraw the securities represented by your ADSs except to comply with mandatory provisions of law.

Voting Rights

As a holder, you generally have the right under the deposit agreement to instruct the depositary to exercise the voting rights for the ordinary shares represented by your ADSs. The voting rights of holders of ordinary shares are described in “Description of Share Capital and Articles of Association—Articles of Association” in this prospectus.

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At our request, the depositary will distribute to you any notice of shareholders’ meeting received from us together with information explaining how to instruct the depositary to exercise the voting rights of the securities represented by ADSs. In lieu of distributing such materials, the depositary may distribute to holders of ADSs instructions on how to receive such materials upon request.

If the depositary timely receives voting instructions from a holder of ADSs, it will endeavor to vote the securities (in person or by proxy) represented by the holder’s ADSs as follows:

• The depositary will vote (or cause the custodian to vote) the ordinary shares held on deposit in accordance with the voting instructions received from the holders of ADSs.

• Holders of ADSs in respect of which no timely voting instructions have been received shall be deemed to have instructed the depositary to give a discretionary proxy to a person designated by us to vote the ordinary shares represented by such holders’ ADSs; provided, however, that no such discretionary proxy shall be given with respect to any matter to be voted upon as to which we inform the depositary that (i) we do not wish such proxy to be given, (ii) substantial opposition exists, or (iii) the rights of holders of ordinary shares may be adversely affected.

Securities for which no voting instructions have been received will not be voted (except as otherwise contemplated in the deposit agreement). Please note that the ability of the depositary to carry out voting instructions may be limited by practical and legal limitations and the terms of the securities on deposit. We cannot assure you that you will receive voting materials in time to enable you to return voting instructions to the depositary in a timely manner.

Fees and Charges

As an ADS holder, you will be required to pay the following fees under the terms of the deposit agreement:

SERVICE	FEE
Issuance of ADSs (e.g., an issuance of ADS upon a deposit of ordinary shares or upon a change in the ADS(s)-to-ordinary shares ratio), excluding ADS issuances as a result of distributions of ordinary shares	Up to $5.00 per 100 ADSs (or fraction thereof) issued
Cancellation of ADSs (e.g., a cancellation of ADSs for delivery of deposited property or upon a change in the ADS(s)-to-ordinary shares ratio)	Up to $5.00 per 100 ADSs (or fraction thereof) cancelled
Distribution of cash dividends or other cash distributions (e.g., upon a sale of rights and other entitlements)	Up to $5.00 per 100 ADSs (or fraction thereof) held
Distribution of ADSs pursuant to (i) share dividends or other free share distributions, or (ii) exercise of rights to purchase additional ADSs	Up to $5.00 per 100 ADSs (or fraction thereof) held
Distribution of securities other than ADSs or rights to purchase additional ADSs (e.g., upon a spin-off)	Up to $5.00 per 100 ADSs (or fraction thereof) held
ADS Services	Up to $5.00 per 100 ADSs (or fraction thereof) held on the applicable record date(s) established by the depositary

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As an ADS holder you will also be responsible to pay certain charges such as:

• taxes (including applicable interest and penalties) and other governmental charges;

• the registration fees as may from time to time be in effect for the registration of ordinary shares on the share register and applicable to transfers of ordinary shares to or from the name of the custodian, the depositary or any nominees upon the making of deposits and withdrawals, respectively;

• certain cable, telex and facsimile transmission and delivery expenses;

• the expenses and charges incurred by the depositary in the conversion of foreign currency;

• the fees and expenses incurred by the depositary in connection with compliance with exchange control regulations and other regulatory requirements applicable to ordinary shares, ADSs and ADRs; and

• the fees and expenses incurred by the depositary, the custodian or any nominee in connection with the servicing or delivery of deposited property.

ADS fees and charges for (i) the issuance of ADSs, and (ii) the cancellation of ADSs are charged to the person to whom the ADSs are issued (in the case of ADS issuances) and to the person whose ADSs are cancelled (in the case of ADS cancellations). In the case of ADSs issued by the depositary into DTC, the ADS issuance and cancellation fees and charges may be deducted from distributions made through DTC, and may be charged to the DTC participant(s) receiving the ADSs being issued or the DTC participant(s) holding the ADSs being cancelled, as the case may be, on behalf of the beneficial owner(s) and will be charged by the DTC participant(s) to the account of the applicable beneficial owner(s) in accordance with the procedures and practices of the DTC participants as in effect at the time. ADS fees and charges in respect of distributions and the ADS service fee are charged to the holders as of the applicable ADS record date. In the case of distributions of cash, the amount of the applicable ADS fees and charges is deducted from the funds being distributed. In the case of (i) distributions other than cash and (ii) the ADS service fee, holders as of the ADS record date will be invoiced for the amount of the ADS fees and charges and such ADS fees and charges may be deducted from distributions made to holders of ADSs. For ADSs held through DTC, the ADS fees and charges for distributions other than cash and the ADS service fee may be deducted from distributions made through DTC, and may be charged to the DTC participants in accordance with the procedures and practices prescribed by DTC and the DTC participants in turn charge the amount of such ADS fees and charges to the beneficial owners for whom they hold ADSs.

In the event of refusal to pay the depositary fees, the depositary may, under the terms of the deposit agreement, refuse the requested service until payment is received or may set off the amount of the depositary fees from any distribution to be made to the ADS holder. Certain depositary fees and charges (such as the ADS services fee) may become payable shortly after the closing of the ADS offering. Note that the fees and charges you may be required to pay may vary over time and may be changed by us and by the depositary. You will receive prior notice of such changes. The depositary may reimburse us for certain expenses incurred by us in respect of the ADR program, by making available a portion of the ADS fees charged in respect of the ADR program or otherwise, upon such terms and conditions as we and the depositary agree from time to time.

Amendments and Termination

We may agree with the depositary to modify the deposit agreement at any time without your consent. We undertake to give holders 30 days’ prior notice of any modifications that would materially prejudice any of their substantial rights under the deposit agreement. We will not consider to be materially prejudicial to your substantial rights any modifications or supplements that are reasonably necessary for the ADSs to be registered under the Securities Act or to be eligible for book-entry settlement, in each case without imposing or increasing the fees and charges you are required to pay. In addition, we may not be able to provide you with prior notice of any modifications or supplements that are required to accommodate compliance with applicable provisions of law.

You will be bound by the modifications to the deposit agreement if you continue to hold your ADSs after the modifications to the deposit agreement become effective. The deposit agreement cannot be amended to prevent you from withdrawing the ordinary shares represented by your ADSs (except as permitted by law).

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We have the right to direct the depositary to terminate the deposit agreement. Similarly, the depositary may in certain circumstances on its own initiative terminate the deposit agreement. In either case, the depositary must give notice to the holders at least 30 days before termination. Until termination, your rights under the deposit agreement will be unaffected.

After termination, the depositary will continue to collect distributions received (but will not distribute any such property until you request the cancellation of your ADSs) and may sell the securities held on deposit. After the sale, the depositary will hold the proceeds from such sale and any other funds then held for the holders of ADSs in a non-interest bearing account. At that point, the depositary will have no further obligations to holders other than to account for the funds then held for the holders of ADSs still outstanding (after deduction of applicable fees, taxes and expenses).

In connection with any termination of the deposit agreement, the depositary may make available to owners of ADSs a means to withdraw the ordinary shares represented by ADSs and to direct the depositary of such ordinary shares into an unsponsored American depositary share program established by the depositary. The ability to receive unsponsored American depositary shares upon termination of the deposit agreement would be subject to satisfaction of certain U.S. regulatory requirements applicable to the creation of unsponsored American depositary shares and the payment of applicable depositary fees.

Books of Depositary

The depositary will maintain ADS holder records at its depositary office. You may inspect such records at such office during regular business hours but solely for the purpose of communicating with other holders in the interest of business matters relating to the ADSs and the deposit agreement.

The depositary will maintain in New York facilities to record and process the issuance, cancellation, combination, split-up and transfer of ADSs. These facilities may be closed from time to time, to the extent not prohibited by law.

Limitations on Obligations and Liabilities

The deposit agreement limits our obligations and the depositary’s obligations to you. Please note the following:

• We and the depositary are obligated only to take the actions specifically stated in the deposit agreement without negligence or bad faith.

• The depositary disclaims any liability for any failure to carry out voting instructions, for any manner in which a vote is cast or for the effect of any vote, provided it acts in good faith and without negligence and in accordance with the terms of the deposit agreement.

• The depositary disclaims any liability for any failure to determine the lawfulness or practicality of any action, for the content of any document forwarded to you on our behalf or for the accuracy of any translation of such a document, for the investment risks associated with investing in ordinary shares, for the validity or worth of the ordinary shares, for any tax consequences that result from the ownership of ADSs, for the credit-worthiness of any third party, for allowing any rights to lapse under the terms of the deposit agreement, for the timeliness of any of our notices or for our failure to give notice.

• We and the depositary will not be obligated to perform any act that is inconsistent with the terms of the deposit agreement.

• We and the depositary disclaim any liability if we or the depositary are prevented or forbidden from or subject to any civil or criminal penalty or restraint on account of, or delayed in, doing or performing any act or thing required by the terms of the deposit agreement, by reason of any provision, present or future of any law or regulation, or by reason of present or future provision of any provision of our Articles of Association, or any provision of or governing the securities on deposit, or by reason of any act of God or war or other circumstances beyond our control.

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• We and the depositary disclaim any liability by reason of any exercise of, or failure to exercise, any discretion provided for in the deposit agreement or in our Articles of Association or in any provisions of or governing the securities on deposit.

• We and the depositary further disclaim any liability for any action or inaction in reliance on the advice or information received from legal counsel, accountants, any person presenting ordinary shares for deposit, any holder of ADSs or authorized representatives thereof, or any other person believed by either of us in good faith to be competent to give such advice or information.

• We and the depositary also disclaim liability for the inability by a holder to benefit from any distribution, offering, right or other benefit that is made available to holders of ordinary shares but is not, under the terms of the deposit agreement, made available to you.

• We and the depositary may rely without any liability upon any written notice, request or other document believed to be genuine and to have been signed or presented by the proper parties.

• We and the depositary also disclaim liability for any consequential or punitive damages for any breach of the terms of the deposit agreement.

• No disclaimer of any Securities Act or Exchange Act liability is intended by any provision of the deposit agreement, in each case to the extent established under applicable U.S. laws.

Nothing in the deposit agreement gives rise to a partnership or joint venture, or establishes a fiduciary relationship, among us, the depositary bank and you as ADS holder.

Nothing in the deposit agreement precludes Citibank (or its affiliates) from engaging in transactions in which parties adverse to us or the ADS owners have interests, and nothing in the deposit agreement obligates Citibank to disclose those transactions, or any information obtained in the course of those transactions, to us or to the ADS owners, or to account for any payment received as part of those transactions.

Taxes

You will be responsible for the taxes and other governmental charges payable on the ADSs and the securities represented by the ADSs. We, the depositary and the custodian may deduct from any distribution the taxes and governmental charges payable by holders and may sell any and all property on deposit to pay the taxes and governmental charges payable by holders. You will be liable for any deficiency if the sale proceeds do not cover the taxes that are due.

The depositary may refuse to issue ADSs; to deliver, transfer, split and combine ADRs; or to release securities on deposit until all taxes and charges are paid by the applicable holder. The depositary and the custodian may take reasonable administrative actions to obtain tax refunds and reduced tax withholding for any distributions on your behalf. However, you may be required to provide to the depositary and to the custodian proof of taxpayer status and residence and such other information as the depositary and the custodian may require to fulfill legal obligations. You are required to indemnify us, the depositary and the custodian for any claims with respect to taxes based on any tax benefit obtained for you.

Foreign Currency Conversion

The depositary will arrange for the conversion of all foreign currency received into U.S. dollars if such conversion is practical, and it will distribute the U.S. dollars in accordance with the terms of the deposit agreement. You may have to pay fees and expenses incurred in converting foreign currency, such as fees and expenses incurred in complying with currency exchange controls and other governmental requirements.

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If the conversion of foreign currency is not practical or lawful, or if any required approvals are denied or not obtainable at a reasonable cost or within a reasonable period, the depositary may take the following actions in its discretion:

• Convert the foreign currency to the extent practical and lawful and distribute the U.S. dollars to the holders for whom the conversion and distribution is lawful and practical.

• Distribute the foreign currency to holders for whom the distribution is lawful and practical.

• Hold the foreign currency (without liability for interest) for the applicable holders.

Governing Law/Waiver of Jury Trial

The deposit agreement, the ADRs and the ADSs will be interpreted in accordance with the laws of the State of New York. The rights of holders of ordinary shares (including ordinary shares represented by ADSs) is governed by the laws of the Cayman Islands.

AS A PARTY TO THE DEPOSIT AGREEMENT, YOU IRREVOCABLY WAIVE YOUR RIGHT TO TRIAL BY JURY, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, IN ANY LEGAL PROCEEDING ARISING OUT OF THE DEPOSIT AGREEMENT OR THE ADRs AGAINST US AND/OR THE DEPOSITARY.

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DESCRIPTION OF UNITS

We may issue units comprised of one or more of the other securities that may be offered under this prospectus, in any combination. The following, together with the additional information we may include in the applicable prospectus supplement, summarizes the material terms and provisions of the units that we may offer under this prospectus. While the terms summarized below will apply generally to any units we may offer, we will describe the particular terms of any series of units in more detail in the applicable prospectus supplement.

Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately at any time, or at any time before a specified date.

Any applicable prospectus supplement will describe:

• the material terms of the units and of the securities comprising the units, including whether and under what circumstances those securities may be held or transferred separately;

• any material provisions relating to the issuance, payment, settlement, transfer or exchange of the units or of the securities comprising the units; and

• any material provisions of the governing unit agreement that differ from those described above.

DESCRIPTION OF WARRANTS

We may issue warrants to purchase ordinary shares or ADSs. We may offer warrants separately or together with one or more additional warrants, ordinary shares or ADSs, or any combination of those securities in the form of units, as described in the applicable prospectus supplement. If we issue warrants as part of a unit, the accompanying prospectus supplement will specify whether those warrants may be separated from the other securities in the unit prior to the expiration date of the warrants. The applicable prospectus supplement will also describe the following terms of any warrants:

• the specific designation and aggregate number of, and the offering price at which we will issue, the warrants;

• the currency or currency units in which the offering price, if any, and the exercise price are payable;

• the date on which the right to exercise the warrants will begin and the date on which that right will expire or, if the holder may not continuously exercise the warrants throughout that period, the specific date or dates on which the holder may exercise the warrants;

• whether the warrants are to be sold separately or with other securities as parts of units;

• whether the warrants will be issued in definitive or global form or in any combination of these forms, although, in any case, the form of a warrant included in a unit will correspond to the form of the unit and of any security included in that unit;

• any applicable material U.S. federal income tax consequences;

• the identity of the warrant agent for the warrants and of any other depositaries, execution or paying agents, transfer agents, registrars or other agents;

• the proposed listing, if any, of the warrants or any securities purchasable upon exercise of the warrants on any securities exchange;

• the designation and terms of any equity securities purchasable upon exercise of the warrants;

• if applicable, the designation and terms of the ordinary shares or ADSs with which the warrants are issued and the number of warrants issued with each security;

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• if applicable, the date from and after which any warrants issued as part of a unit and the related ordinary shares or ADSs will be separately transferable;

• the number of ordinary shares or the number of ADSs purchasable upon exercise of a warrant and the price at which those shares may be purchased;

• if applicable, the minimum or maximum amount of the warrants that may be exercised at any one time;

• information with respect to book-entry procedures, if any;

• the antidilution provisions of, and other provisions for changes to or adjustment in the exercise price of, the warrants, if any;

• any redemption or call provisions; and

• any additional terms of the warrants, including terms, procedures and limitations relating to the exchange or exercise of the warrants.

FORMS OF SECURITIES

Each unit and warrant will be represented either by a certificate issued in definitive form to a particular investor or by one or more global securities representing the entire issuance of securities. Unless the applicable prospectus supplement provides otherwise, certificated securities will be issued in definitive form and global securities will be issued in registered form. Definitive securities name you or your nominee as the owner of the security, and in order to transfer or exchange these securities or to receive payments other than interest or other interim payments, you or your nominee must physically deliver the securities to the registrar, paying agent or other agent, as applicable. Global securities name a depositary or its nominee as the owner of the units or warrants represented by these global securities. The depositary maintains a computerized system that will reflect each investor’s beneficial ownership of the securities through an account maintained by the investor with its broker/dealer, bank, trust company or other representative, as we explain more fully below.

Global Securities

We may issue the units and warrants in the form of one or more fully registered global securities that will be deposited with a depositary or its nominee identified in the applicable prospectus supplement and registered in the name of that depositary or nominee. In those cases, one or more global securities will be issued in a denomination or aggregate denominations equal to the portion of the aggregate principal or face amount of the securities to be represented by global securities. Unless and until it is exchanged in whole for securities in definitive registered form, a global security may not be transferred except as a whole by and among the depositary for the global security, the nominees of the depositary or any successors of the depositary or those nominees.

If not described below, any specific terms of the depositary arrangement with respect to any securities to be represented by a global security will be described in the prospectus supplement relating to those securities. We anticipate that the following provisions will apply to all depositary arrangements.

Ownership of beneficial interests in a global security will be limited to persons, called participants, that have accounts with the depositary or persons that may hold interests through participants. Upon the issuance of a global security, the depositary will credit, on its book-entry registration and transfer system, the participants’ accounts with the respective principal or face amounts of the securities beneficially owned by the participants. Any dealers, underwriters or agents participating in the distribution of the securities will designate the accounts to be credited. Ownership of beneficial interests in a global security will be shown on, and the transfer of ownership interests will be effected only through, records maintained by the depositary, with respect to interests of participants, and on the records of participants, with respect to interests of persons holding through

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participants. The laws of some states may require that some purchasers of securities take physical delivery of these securities in definitive form. These laws may impair your ability to own, transfer or pledge beneficial interests in global securities.

So long as the depositary, or its nominee, is the registered owner of a global security, that depositary or its nominee, as the case may be, will be considered the sole owner or holder of the securities represented by the global security for all purposes under the applicable warrant agreement or unit agreement. Except as described below, owners of beneficial interests in a global security will not be entitled to have the securities represented by the global security registered in their names, will not receive or be entitled to receive physical delivery of the securities in definitive form and will not be considered the owners or holders of the securities under the applicable unit agreement or warrant agreement. Accordingly, each person owning a beneficial interest in a global security must rely on the procedures of the depositary for that global security and, if that person is not a participant, on the procedures of the participant through which the person owns its interest, to exercise any rights of a holder under the applicable unit agreement or warrant agreement. We understand that under existing industry practices, if we request any action of holders or if an owner of a beneficial interest in a global security desires to give or take any action that a holder is entitled to give or take under the applicable unit agreement or warrant agreement, the depositary for the global security would authorize the participants holding the relevant beneficial interests to give or take that action, and the participants would authorize beneficial owners owning through them to give or take that action or would otherwise act upon the instructions of beneficial owners holding through them.

Any payments to holders with respect to warrants or units represented by a global security registered in the name of a depositary or its nominee will be made to the depositary or its nominee, as the case may be, as the registered owner of the global security. None of us, or any warrant agent, unit agent or other agent of ours, or any agent of any warrant agent or unit agent will have any responsibility or liability for any aspect of the records relating to payments made on account of beneficial ownership interests in the global security or for maintaining, supervising or reviewing any records relating to those beneficial ownership interests.

We expect that the depositary for any of the securities represented by a global security, upon receipt of any payment to holders of principal, premium, interest or other distribution of underlying securities or other property on that registered global security, will immediately credit participants’ accounts in amounts proportionate to their respective beneficial interests in that global security as shown on the records of the depositary. We also expect that payments by participants to owners of beneficial interests in a global security held through participants will be governed by standing customer instructions and customary practices, as is now the case with the securities held for the accounts of customers or registered in “street name,” and will be the responsibility of those participants.

If the depositary for any of the securities represented by a global security is at any time unwilling or unable to continue as depositary or ceases to be a clearing agency registered under the Exchange Act, and a successor depositary registered as a clearing agency under the Exchange Act is not appointed by us within 90 days, we will issue securities in definitive form in exchange for the global security that had been held by the depositary. Any securities issued in definitive form in exchange for a global security will be registered in the name or names that the depositary gives to the relevant warrant agent, unit agent or other relevant agent of ours or theirs. It is expected that the depositary’s instructions will be based upon directions received by the depositary from participants with respect to ownership of beneficial interests in the global security that had been held by the depositary.

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TAXATION

Material U.S. Federal Income Tax Considerations for U.S. Holders

A general summary of the material U.S. federal income tax consequences relating to the purchase, ownership and disposition of any of the securities offered by this prospectus will be set forth in a prospectus supplement relating to the offering of those securities.

Cayman Island Taxation

A general summary of certain Cayman Island tax considerations relating to the purchase, ownership and disposition of any of the securities offered by this prospectus will be set forth in a prospectus supplement relating to the offering of those securities.

PLAN OF DISTRIBUTION

We may sell securities:

• through underwriters;

• through dealers;

• through agents;

• directly to purchasers; or

• through a combination of any of these methods of sale.

In addition, we may issue the securities as a dividend or distribution or in a subscription rights offering to our existing security holders. This prospectus may be used in connection with any offering of our securities through any of these methods or other methods described in the applicable prospectus supplement.

We may directly solicit offers to purchase securities, or agents may be designated to solicit such offers. We will, in the prospectus supplement relating to such offering, name any agent that could be viewed as an underwriter under the Securities Act, and describe any commissions that we must pay. Any such agent will be acting on a best efforts basis for the period of its appointment or, if indicated in the applicable prospectus supplement, on a firm commitment basis.

The distribution of the securities may be effected from time to time in one or more transactions:

• at a fixed price, or prices, which may be changed from time to time;

• at market prices prevailing at the time of sale;

• at prices related to such prevailing market prices; or

• at negotiated prices.

Each prospectus supplement will describe the method of distribution of the securities and any applicable restrictions.

The prospectus supplement with respect to the securities of a particular series will describe the terms of the offering of the securities, including the following:

• the name of the agent or any underwriters;

• the public offering or purchase price and the proceeds we will receive from the sale of the securities;

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• any discounts and commissions to be allowed or re-allowed or paid to the agent or underwriters;

• all other items constituting underwriting compensation;

• any discounts and commissions to be allowed or re-allowed or paid to dealers; and

• any exchanges on which the securities will be listed.

If any underwriters or agents are utilized in the sale of the securities in respect of which this prospectus is delivered, we will enter into an underwriting agreement or other agreement with them at the time of sale to them, and we will set forth in the prospectus supplement relating to such offering the names of the underwriters or agents and the terms of the related agreement with them.

If a dealer is utilized in the sale of the securities in respect of which this prospectus is delivered, we will sell such securities to the dealer, as principal. The dealer may then resell such securities to the public at varying prices to be determined by such dealer at the time of resale.

If we offer securities in a subscription rights offering to our existing security holders, we may enter into a standby underwriting agreement with dealers acting as standby underwriters. We may pay the standby underwriters a commitment fee for the securities they commit to purchase on a standby basis. If we do not enter into a standby underwriting arrangement, we may retain a dealer-manager to manage a subscription rights offering for us.

Remarketing firms, agents, underwriters, dealers and other persons may be entitled under agreements which they may enter into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, and may be customers of, engage in transactions with or perform services for us in the ordinary course of business.

If so indicated in the applicable prospectus supplement, we will authorize underwriters or other persons acting as our agents to solicit offers by certain institutions to purchase securities from us pursuant to delayed delivery contracts providing for payment and delivery on the date stated in the prospectus supplement. Each contract will be for an amount not less than, and the aggregate amount of securities sold pursuant to such contracts shall not be less nor more than, the respective amounts stated in the prospectus supplement. Institutions with whom the contracts, when authorized, may be made include commercial and savings banks, insurance companies, pension funds, investment companies, educational and charitable institutions and other institutions, but shall in all cases be subject to our approval. Delayed delivery contracts will not be subject to any conditions except that:

• the purchase by an institution of the securities covered under that contract shall not at the time of delivery be prohibited under the laws of the jurisdiction to which that institution is subject; and

• if the securities are also being sold to underwriters acting as principals for their own account, the underwriters shall have purchased such securities not sold for delayed delivery. The underwriters and other persons acting as our agents will not have any responsibility in respect of the validity or performance of delayed delivery contracts.

Certain agents, underwriters and dealers, and their associates and affiliates, may be customers of, have borrowing relationships with, engage in other transactions with and/or perform services, including investment banking services, for us or one or more of our respective affiliates in the ordinary course of business.

In order to facilitate the offering of the securities, any underwriters may engage in transactions that stabilize, maintain or otherwise affect the price of the securities or any other securities the prices of which may be used to determine payments on such securities. Specifically, any underwriters may overallot in connection with the offering, creating a short position for their own accounts. In addition, to cover overallotments or to stabilize the price of the securities or of any such other securities, the underwriters may bid for, and purchase, the securities or

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any such other securities in the open market. Finally, in any offering of the securities through a syndicate of underwriters, the underwriting syndicate may reclaim selling concessions allowed to an underwriter or a dealer for distributing the securities in the offering if the syndicate repurchases previously distributed securities in transactions to cover syndicate short positions, in stabilization transactions or otherwise. Any of these activities may stabilize or maintain the market price of the securities above independent market levels. Any such underwriters are not required to engage in these activities and may end any of these activities at any time.

Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in two business days, unless the parties to any such trade expressly agree otherwise or the securities are sold by us to an underwriter in a firm commitment underwritten offering. The applicable prospectus supplement may provide that the original issue date for your securities may be more than two scheduled business days after the trade date for your securities. Accordingly, in such a case, if you wish to trade securities on any date prior to the second business day before the original issue date for your securities, you will be required, by virtue of the fact that your securities initially are expected to settle in more than two scheduled business days after the trade date for your securities, to make alternative settlement arrangements to prevent a failed settlement.

The securities may be new issues of securities and may have no established trading market. The securities may or may not be listed on a national securities exchange. We can make no assurance as to the liquidity of or the existence of trading markets for any of the securities.

In compliance with the guidelines of the Financial Industry Regulatory Authority, or FINRA, the aggregate maximum discount, commission or agency fees or other items constituting underwriting compensation to be received by any FINRA member or independent broker-dealer will not exceed 8% of the proceeds from any offering pursuant to this prospectus and any applicable prospectus supplement.

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LEGAL MATTERS

Unless the applicable prospectus supplement indicates otherwise, certain legal matters of U.S. federal law and New York State law will be passed upon for us by Wilmer Cutler Pickering Hale and Dorr LLP. Unless the applicable prospectus supplement indicates otherwise, the validity of the securities in respect of which this prospectus is being delivered and certain legal matters with respect to Cayman Island law will be passed upon by Walkers.

EXPERTS

The financial statements incorporated in this prospectus by reference from the Company’s Annual Report on Form 20-F have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report, which is incorporated herein by reference. Such financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

The registered business address of Deloitte & Touche LLP is 200 Berkeley Street, Boston, Massachusetts 02116.

EXPENSES

The following table sets forth the expenses (other than underwriting discounts and commissions) expected to be incurred by us in connection with a possible offering of $75,000,000.00 of the securities registered under this registration statement. All amounts other than the SEC registration fee are estimates.

SEC registration fee	$	9,735
FINRA filing fee		*
Printing and engraving		*
Accounting services		*
Nasdaq fees		*
Legal fees of registrant’s counsel		*
Transfer agent’s and depositary’s fees and expenses		*
Miscellaneous		*
Total	$	*

* To be provided by a prospectus supplement or as an exhibit to a Report on Form 6-K that is incorporated by reference into this prospectus.

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ENFORCEMENT OF CIVIL LIABILITIES

Our agent for service of process in the United States is Stealth Delaware, and the executive offices of Stealth Delaware are located at 275 Grove Street, Suite 3-107, Newton, MA 02466, and the telephone number there is (617) 600-6888.

We are incorporated under the laws of the Cayman Islands. We have been advised that there is some doubt as to the enforceability in the Cayman Islands, in original actions or in actions for enforcement of judgments of the U.S. courts, of civil liabilities based solely on the federal securities laws of the United States. In addition, awards for punitive damages in actions brought in the United States, or elsewhere may be unenforceable in the Cayman Islands. An award for monetary damages under the U.S. securities laws would be considered punitive if it does not seek to compensate the claimant for loss or damage suffered and is intended to punish the defendant. The enforceability of any judgment in the Cayman Islands will depend on the particular facts of the case as well as the laws and treaties in effect at the time. The United States and the Cayman Islands do not currently have a treaty providing for recognition and enforcement of judgments (other than arbitration awards) in civil and commercial matters.

We have been advised by our Cayman Islands legal counsel that the Cayman Islands Court is unlikely (i) to recognize or enforce against us judgments of the courts of the United States predicated upon the civil liability provisions of the federal securities laws of the United States or any state; and (ii) in original actions brought in the Cayman Islands, to impose liabilities against us predicated upon the civil liability provisions of the federal securities laws of the United States or any state, so far as the liabilities imposed by those provisions are penal in nature. In certain circumstances, although there is no statutory enforcement in the Cayman Islands of judgments obtained in the United States, the Cayman Islands Court will recognize and enforce a foreign money judgment of a foreign court of competent jurisdiction without retrial on the merits and based on the principle that a judgment of a competent foreign court imposes upon the judgment debtor an obligation to pay the sum for which judgment has been given provided certain conditions are met. For a foreign judgment to be enforced in the Cayman Islands, such judgment must be final and conclusive and for a liquidated sum, and must not be in respect of taxes or a fine or penalty , inconsistent with a Cayman Islands judgment in respect of the same matter, impeachable on the grounds of fraud or obtained in a manner, and or be of a kind the enforcement of which is, contrary to natural justice or the public policy of the Cayman Islands (awards of punitive or multiple damages may well be held to be contrary to public policy). The Cayman Islands Court may stay enforcement proceedings if concurrent proceedings are being brought elsewhere.

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2,339,000 American Depositary Shares

Representing 28,068,000 Ordinary Shares

PROSPECTUS SUPPLEMENT

H.C. Wainwright & Co.

February 9, 2021