UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.    )

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Horizon Therapeutics Public Limited Company

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if other than the Registrant)

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HORIZON THERAPEUTICS PUBLIC LIMITED COMPANY

ANNUAL GENERAL MEETING OF SHAREHOLDERS

April 28, 2022

NOTICE AND PROXY STATEMENT

March 17, 2022

Dear Fellow Shareholder:

2021 was a milestone year for Horizon. We significantly expanded our pipeline, generated top-tier growth and continued to make a difference in the lives of people impacted by rare, autoimmune and severe inflammatory diseases. Our continued strong strategic execution resulted in record full-year total net sales of $3.2 billion, representing year-over-year growth of 47 percent, and record full-year adjusted EBITDA⁽¹⁾ of $1.3 billion, representing year-over-year growth of 33 percent. We ended 2021 with cash and cash equivalents of $1.6 billion, giving us the flexibility to pursue future business development initiatives, supporting our strategy to further expand our pipeline. Our strong performance translated into significant shareholder returns, with our one-, three- and five-year total shareholder returns of 47 percent, 451 percent and 566 percent, respectively, far exceeding those of our peer group⁽²⁾ and the Nasdaq Biotechnology Index.

One of our key strategic goals is to expand our pipeline, through business development as well as maximizing the potential of our existing medicines and candidates. 2021 was a year of tremendous progress on both fronts. Our acquisition of Viela Bio in March dramatically expanded our pipeline, with Viela’s mid-stage biologics pipeline of four candidates in nine development programs. We also welcomed Viela’s talented R&D team with deep early-stage research and clinical development capabilities. In September, at our inaugural R&D day, in addition to discussing our R&D strategy and showcasing our team, we announced new development programs in five additional indications for two of our candidates, further expanding our pipeline. In addition, during the year we announced two collaborations to advance our early-stage research and innovation capabilities. We successfully completed two clinical trials and initiated seven clinical trials. This year we plan to initiate seven clinical trials and have already initiated two of them, our Phase 2b trial for HZN-825 for the treatment of idiopathic pulmonary fibrosis, in January, and our Phase 3 clinical trial for TEPEZZA in thyroid eye disease (TED) in Japan (OPTIC-J), in February. Our pipeline, balanced across the development life cycle, now includes more than 20 programs, with the majority of them added in 2021. With a focus on addressing critical unmet needs for patients, our pipeline is designed to drive long-term sustainable growth for Horizon.

Our excellence in commercial execution is evidenced by the progress we made during the year with our three key growth drivers TEPEZZA^®, KRYSTEXXA^® and UPLIZNA^®. We more than doubled the full-year net sales of TEPEZZA, our biologic approved for the treatment of TED, to $1.7 billion in its second year post-launch, representing impressive growth of 103 percent. We achieved this strong performance, despite the continued impact of the COVID-19 pandemic, as well as a supply disruption that resulted from government-mandated COVID-19 vaccine production at our manufacturing partner’s facilities. The government-mandated order resulted in a total disruption of TEPEZZA supply from the end of 2020 to April 2021. Through the outstanding execution of our commercial team, we rapidly overcame the impact of the disruption with a highly successful relaunch beginning once supply resumed in April. We see strong growth prospects for TEPEZZA and we continue to invest to support that growth, from our initiatives to drive increased awareness of TEPEZZA and TED, to our clinical trials in chronic TED and TED in Japan. We are well on our way to achieve our projected peak global annual net sales of greater than $3.5 billion.

Record annual net sales for KRYSTEXXA, our biologic for uncontrolled gout, grew 39 percent year-over-year to $565.5 million – impressive growth for a 12-year-old medicine. Driving much of the growth is the increasing use of KRYSTEXXA plus immunomodulation. Since 2017, to make the medicine available to more patients, we focused on increasing the response rate to KRYSTEXXA through our clinical immunomodulation strategy. In 2021, we announced positive topline data from our MIRROR randomized controlled trial, which demonstrated that 71 percent of patients who received KRYSTEXXA plus the immunomodulator methotrexate achieved a complete response compared to 39 percent who received KRYSTEXXA plus placebo. In January we submitted a Supplemental Biologics License Application (sBLA) to the U.S. Food and Drug Administration (FDA) to expand the label for KRYSTEXXA to include co-treatment with methotrexate. We believe KRYSTEXXA plus immunomodulation is redefining the standard of care for KRYSTEXXA, which is on track to achieve our projected peak U.S. annual net sales estimate of greater than $1 billion.

UPLIZNA, our third key growth driver, came to us with the Viela acquisition. UPLIZNA, which was approved in 2020 by the U.S. Food and Drug Administration for neuromyelitis optica spectrum disorder (NMOSD), was launched by Viela during the peak of the COVID-19 pandemic in June 2020, with relatively minimal resources. We successfully relaunched the medicine in the fourth quarter of 2021, backed by our expertise in commercializing rare disease medicines. Internationally, we made strides in building out the infrastructure and capabilities necessary to support the potential 2022 launch of UPLIZNA in Europe, as well as other global markets in the coming years. We have Phase 3 clinical trials underway evaluating UPLIZNA for myasthenia gravis (MG) and IgG4-related disease. We estimate potential peak global annual net sales of greater than $1 billion for UPLIZNA in NMOSD, MG and IgG4-related disease.⁽³⁾

At Horizon, our mission is simple and powerful: to improve people’s lives. We go to incredible lengths to make the world a better place by addressing unmet medical needs; by building healthier communities, urgently and responsibly; and by giving back to our communities. Behind all of our efforts are the people who make up Horizon and their dedication to making a difference in the lives of others. Our employees are highly engaged, evidenced by the 15 workplace-related awards we received in 2021 – including ranking as the Number 1 biotech/pharmaceutical company in FORTUNE’s 100 Best Companies to Work For^®. We believe our high employee engagement – important in an industry as competitive as ours – is partly due to the many ways we strive to make working at Horizon attractive and rewarding. We were very pleased in 2021 to demonstrate continued gender and ethnicity pay equity in the second study conducted by Aon, after the dramatic growth in our workforce since the 2019 study, including the addition of a significant number of employees with the Viela acquisition.

Horizon today is a leading, high-growth, innovation-driven, profitable biotech company. One of the people who has been instrumental in our transformation is Paul Hoelscher, our executive vice president, chief financial officer. In October 2021, Paul notified us of his intention to retire in May 2022, continuing on as an advisor through May 2023. Paul has served as our CFO since 2014 and has been a valued partner to me these past seven years. Speaking for all of us at Horizon, I thank him for his leadership, his dedication and his commitment to our mission – and especially for the many successful initiatives he has spearheaded to build Horizon’s strong financial position. Aaron Cox, executive vice president, finance, will succeed Paul as CFO. Aaron, with his extensive knowledge of the business and strong financial background, has been a leader in many of our major strategic efforts and has led our corporate development and capital markets initiatives. I am confident that Aaron, along with our deeply experienced financial leadership team that Paul put in place, will continue to support our long-term strategy.

In summary, 2021 was a year of significant progress, multiple milestones and record financial results. With our highly focused strategy, strong execution and business development and R&D capabilities, we believe we are well positioned to deliver sustainable top-tier growth and shareholder value going forward.

You are cordially invited to attend our Annual General Meeting of Shareholders on Thursday, April 28, 2022, at 3:00 p.m. local time at our new corporate headquarters, located at 70 St. Stephen’s Green, Dublin 2, D02 E2X4, Ireland. Whether or not you plan to attend, it is important that your shares be represented and voted. Please take a moment now to vote your shares using the instructions found in the Notice of Internet Availability of Proxy Materials and in this Proxy Statement. Your vote is important, and we appreciate your continued support.

Sincerely,

Timothy P. Walbert

Chairman, President and Chief Executive Officer

Horizon Therapeutics Public Limited Company

70 St. Stephen’s Green, Dublin 2, D02 E2X4, Ireland

NOTICE OF ANNUAL GENERAL MEETING OF SHAREHOLDERS TO BE HELD ON APRIL 28, 2022

Dear Shareholder:

We will be holding the Annual General Meeting of Shareholders of Horizon Therapeutics Public Limited Company on Thursday, April 28, 2022, at 3:00 p.m. local time at our corporate headquarters located at 70 St. Stephen’s Green, Dublin 2, D02 E2X4, Ireland, for the following purposes:

These items of business are more fully described in the Proxy Statement accompanying this Notice.

The Board recommends that you vote FOR each of the nominees for director named herein and FOR Proposals 2, 3, 4 and 5. The accompanying Proxy Statement contains additional information and should be carefully reviewed by shareholders.

Our Irish statutory financial statements for the fiscal year ended December 31, 2021, including the reports of the directors and statutory auditors thereon, will be presented at the Annual General Meeting. There is no requirement under Irish law that such statements be approved by the shareholders and no such approval will be sought at the Annual General Meeting.

For the purposes of our Articles of Association, Proposals 1 and 2 and the receipt and consideration of the Irish statutory financial statements by us at the Annual General Meeting are deemed to be ordinary business and Proposals 3, 4 and 5 are deemed to be special business. The Annual General Meeting will also include a review of the Company’s affairs. Shareholders of record as of February 24, 2022, the record date for the Annual General Meeting, are entitled to notice of the Annual General Meeting and to vote at the Annual General Meeting or any adjournment or postponement thereof.

As permitted by the U.S. Securities and Exchange Commission, we are making this Proxy Statement and Horizon’s Annual Report to shareholders available to our shareholders electronically through the internet, accessible at http://materials.proxyvote.com/ G46188 and also on the Annual Reports/Proxy Statements page of our website at www.horizontherapeutics.com. We believe this electronic distribution model, known as Notice and Access, provides our shareholders a convenient and expedited method to access the proxy materials and vote, while allowing us to conserve natural resources and reduce the environmental impact of our Annual General Meeting. In addition, it reduces the costs of printing and distributing the proxy materials.

By Order of the Board of Directors

David Caraher

Company Secretary

Dublin, Ireland

March 17, 2022

If you are a shareholder of record on February 24, 2022, you are cordially invited to attend the Annual General Meeting in person. Whether or not you expect to attend the meeting, please complete, date, sign and return the proxy mailed to you, or vote over the telephone or the internet as instructed in these materials, as promptly as possible in order to ensure your representation at the meeting. Even if you have voted by proxy, you may still vote in person if you attend the meeting. Please note, however, that if your shares are held of record by a broker, bank or other nominee and you wish to vote at the meeting, you must obtain a proxy issued in your name from that record holder.

We are closely monitoring developments related to COVID-19. It could become necessary to change the date, time, location and/ or means of holding the Annual General Meeting (including by means of remote communication). If such a change is made, we will announce the change in advance, and details on how to participate will be issued by press release, posted on our website and filed as additional proxy materials.

TABLE OF CONTENTS

PROXY STATEMENT SUMMARY

This summary highlights certain information contained elsewhere in this Proxy Statement and does not contain all of the information that you should consider. You should read the entire Proxy Statement carefully before voting. For more complete information regarding our business and 2021 performance, please review our Annual Report on Form 10-K for the year ended December 31, 2021 and our subsequent filings with the Securities and Exchange Commission (SEC).

Voting Items and Board Recommendations

Director Nominees and Continuing Directors

Horizon  |  2022 Proxy Statement 1

2021 – Year at a Glance

Net sales and adjusted EBITDA growth percentages represent year-over-year growth over full-year 2020.

Prior TSR results are not intended to forecast or be indicative of possible future performance of our ordinary shares.

EBITDA: Earnings before interest, taxes, depreciation and amortization. | TSR: Total shareholder return through December 31, 2021. | NBI: Nasdaq Biotechnology Index.

A Milestone Year in Our Transformation

Horizon  |  2022 Proxy Statement 2

Business Overview

Horizon at a Glance

What Sets Us Apart

KRYSTEXXA exemplifies our excellence in commercial execution. An underperforming and undervalued medicine when we acquired it in 2016, with our investment, expertise and deep knowledge of the rheumatology space, we executed on the right commercial strategy for KRYSTEXXA to jump start its growth trajectory. We know how to effectively market rare disease medicines, demonstrated by the fact that we have increased the annual net sales of KRYSTEXXA nearly ten-fold since acquiring it, and we are well on our way toward our projected peak U.S. annual net sales of more than $1 billion.

The returns we have generated to date also attest to the success of our business development efforts. For example, we acquired TEPEZZA for an upfront payment of $145 million plus milestones in 2017; in the two years since its launch, we have generated cumulative net sales of $2.5 billion, despite the negative impact of the COVID-19 pandemic, representing exceptional value creation for our shareholders – and we see opportunities for continued growth for TEPEZZA, projecting peak global annual net sales of more than $3.5 billion. Importantly, TEPEZZA has brought hope for patients with thyroid eye disease (TED), who before TEPEZZA had no approved treatment options. Our strong business development acumen also resulted in the transformational acquisition of Viela Bio in 2021. It significantly expanded our pipeline with the addition of Viela’s four development candidates across nine development programs and three new therapeutic areas. It also expanded our commercial portfolio with the addition of UPLIZNA, a recently approved biologic for the treatment of neuromyelitis optica spectrum disorder (NMOSD).

The Viela acquisition also augmented our strong research and development capabilities. Viela’s talented R&D team, with its early-stage research and clinical development capabilities, highly complements our proven late-stage development capabilities.

Horizon  |  2022 Proxy Statement 3

Leveraging our combined strengths has already driven innovation. In September 2021, we announced pipeline programs in five additional indications for two of the Viela biologic candidates. In addition to adding depth to our pipeline, these programs aim to address high unmet medical needs for patients living with the rare diseases the programs target. Our R&D capabilities also drive innovation of our on-market medicines to maximize their benefit. Our successful MIRROR registrational trial is a testament to this: 71 percent of patients receiving KRYSTEXXA plus the immunomodulator methotrexate achieved a complete response, a more than 30-percentage-point improvement compared to patients who received KRYSTEXXA plus placebo.

Our Pipeline: A Top Strategic Priority to Drive Long-Term Growth

One of our key strategic goals to support our ambitious growth objectives is to expand our pipeline, which we are doing through internal investment and external business development. 2021 was a year of tremendous progress in this regard – we significantly expanded our pipeline with the Viela acquisition, we added five new clinical programs and we augmented our early-stage discovery efforts with two collaborations for novel therapeutics.

A key part of our R&D strategy is maximizing the full potential of our pipeline. In determining new indications to pursue, we evaluate four major areas to identify the disease states that have the most overall potential for success: scientific rationale, unmet need, the competitive landscape and feasibility. We are also building out our discovery pipeline of novel programs by using a balanced approach of internal research and external collaborations while aligning with our core focus areas: rheumatology, nephrology, ophthalmology, endocrinology, neuroimmunology, dermatology and respiratory. Our goal is to generate high-quality investigational new drug applications (INDs) over the coming years.

Our pipeline is balanced across the development life cycle, with early- to late-stage programs. Currently with more than 20 programs – the majority of which were added in 2021 – the pipeline is designed to support sustainable growth over the long-term. We plan to initiate seven clinical trials this year, two of which have already been initiated.

Underscoring all of our pipeline – and our commercial and business development – initiatives is our focus is on addressing the unmet medical needs of patients with rare, autoimmune and severe inflammatory diseases. This is part of our purpose – to make a meaningful difference in the lives of patients, their caregivers, their physicians and the communities we serve.

(1)   Planned program expected to initiate in 2022. Of these programs, the HZN-825 IPF clinical trial initiated in January 2022 and the TEPEZZA TED in Japan (OPTIC-J) initiated in February 2022.   We also have four Phase 4 programs: TEPEZZA chronic TED trial, KRYSTEXXA shorter infusion duration trial, KRYSTEXXA monthly dosing trial and KRYSTEXXA retreatment trial. | TED: Thyroid Eye Disease.

Horizon  |  2022 Proxy Statement 4

Our Key Growth Drivers: TEPEZZA, KRYSTEXXA and UPLIZNA

Our biologic TEPEZZA is the first and only medicine indicated for the treatment of thyroid eye disease (TED), a serious, progressive and potentially vision-threatening, rare autoimmune disease. Launched shortly after approval in January 2020, TEPEZZA is one of the most successful rare disease medicine launches ever. Our significant pre-launch investment in educating physicians and key stakeholders about TED, as well as our teams’ superlative execution, have driven cumulative net sales of $2.5 billion since launch, despite the impact of the COVID-19 pandemic and an over-three-month supply disruption in 2021 due to government-mandated COVID-19 vaccine production orders. We expect continued growth for TEPEZZA in the years ahead, driven by three key growth opportunities: increasing new prescribers while driving additional uptake in our existing prescriber base; increasing the use of TEPEZZA in patients with chronic TED; and maximizing the medicine’s potential through global expansion. We are supporting our efforts in chronic TED with a Phase 4 clinical trial and supporting global expansion with a Phase 3 trial in TED in Japan. We remain confident about the prospects for helping more patients living with this debilitating disease and estimate TEPEZZA peak global annual net sales of more than $3.5 billion.

Since acquiring KRYSTEXXA, our biologic medicine for uncontrolled gout, in 2016, we have transformed its growth trajectory through our strong strategic execution, our deep knowledge of both rheumatology and rare disease medicines, and by investing commercially to support future growth. We’ve also invested significantly to maximize the benefit of KRYSTEXXA so more patients can benefit from the medicine. We announced positive topline data in 2021 from our MIRROR randomized controlled trial, which evaluated KRYSTEXXA plus the immunomodulator methotrexate. We recently submitted a supplemental biologics license application (sBLA) to expand the label for KRYSTEXXA to include co-treatment with methotrexate. We expect the use of KRYSTEXXA plus immunomodulation, which has been steadily increasing, to redefine the standard of care. We see several additional growth opportunities for KRYSTEXXA: expanding uptake in rheumatology and nephrology; elevating the urgency to treat and investing to improve the patient experience. We are well on track toward achieving our projected KRYSTEXXA peak U.S. annual net sales of more than $1 billion.

Our growth driver UPLIZNA is approved for NMOSD, a rare, severe, relapsing, neuroinflammatory autoimmune disease that attacks the optic nerve, spinal cord, brain and brain stem. UPLIZNA was launched by Viela in June 2020, during the height of the COVID-19 pandemic, with relatively minimal resources. Since acquiring Viela, we’ve executed a full relaunch of UPLIZNA, putting the commercial infrastructure and team in place to best support an infused rare disease medicine, launching a new brand campaign and investing to develop a scientific leadership position in NMOSD. We are also building the infrastructure and capabilities necessary to launch UPLIZNA in Europe, where approval is pending, as well as other global markets in the coming years. We see additional development opportunities for UPLIZNA and are pursuing two other indications: myasthenia gravis (MG) and IgG4-related disease. We project peak global annual net sales of more than $1 billion for UPLIZNA in NMOSD and the MG and IgG4-related disease indications we are pursuing.

Total Shareholder Return

Our disciplined approach, clear strategy, business development capabilities, and strong commercial and R&D execution have all worked together to generate consistent above-market returns for our shareholders. Our total shareholder return (TSR) significantly outperformed both our peer group and the Nasdaq Biotechnology Index (NBI) over the one-, three- and five-year periods ended December 31, 2021. With our expanded pipeline and key growth medicines, we believe Horizon is well positioned for sustainable long-term growth.

Horizon  |  2022 Proxy Statement 5

Our Total Shareholder Returns Significantly Surpassed Our Peers⁽¹⁾ and NBI

1-, 3- and 5-Year Periods Ended December 31, 2021

Board Highlights

The Nominating and Corporate Governance Committee of our Board examines multiple factors when evaluating directors, including their knowledge, skills and experience, including experience in our industry and with respect to clinical development, sales and marketing, business development, finance, management and public service. The table below highlights the extensive experience of our directors as well as the balance of skills on our Board:

Our Board of Directors: Skills and Experience Matrix

Horizon  |  2022 Proxy Statement 6

Our Board is predominantly independent and includes a range of expertise, experience, diversity, as well as newer and longer-tenured directors. As is set forth in its diversity policy, the Board values diversity and believes that maintaining a diverse membership enhances the Board’s deliberations and enables it to better represent all of Horizon’s constituents. As such, the Nominating and Corporate Governance Committee works to ensure that the Board represents a diversity of experience and perspectives, as well as race, gender, geography and areas of expertise. A strong, annual director assessment process has resulted in periodic refreshment, enhancing the Board’s effectiveness. Board committee memberships are also refreshed periodically.

Our Board of Directors: Gender and Ethnicity Diversity Matrix

As of March 15, 2022

Horizon  |  2022 Proxy Statement 7

Corporate Governance Highlights

Executive Compensation Overview

Our executive compensation program emphasizes three major pay considerations: long-term performance, executive and shareholder alignment and risk mitigation. Here is how we currently achieve them:

Horizon  |  2022 Proxy Statement 8

With a strategic focus on growing the business over the long term, it is imperative that our executive compensation program motivates our talented management team in a manner that encourages – and rewards – successful execution of this business strategy. We utilize the following compensation elements to achieve this:

Please see our Compensation Discussion and Analysis on page 39 for additional information on our compensation philosophy.

Shareholder Engagement

We value the views of our shareholders. During the outreach we conduct each year, generally led by a member of the Board of Directors, we have had significant and meaningful dialogue with our shareholders regarding our compensation and governance. Feedback from our outreach informs the Compensation Committee’s thinking when evaluating our current compensation program and considering potential modifications going forward. It also informs the Nominating and Corporate Governance Committee’s thinking when evaluating our corporate governance as well as social and environmental (ESG) matters.

Changes to our compensation program and corporate governance over the past several years that were heavily influenced by shareholder feedback include:

Horizon  |  2022 Proxy Statement 9

During our shareholder engagement cycle before our Annual General Meeting in April 2021, as well as during our off-season shareholder engagement cycle in late 2021/early 2022, we offered engagement opportunities to shareholders who represented approximately 60 percent of our shares outstanding. Shareholder feedback from the subsequent engagement was positive. At our 2021 Annual General Meeting, our say-on-pay proposal received the support of approximately 96 percent of the shares voted. We believe this high level of support is partly a result of our comprehensive shareholder outreach and engagement program to solicit feedback, understand investor viewpoints and incorporate their feedback into future evaluations of our compensation programs.

In addition to our outreach on compensation and governance, we have also engaged with shareholders on ESG matters. During this ongoing ESG-related outreach, which we started in 2019, we discuss ESG factors and matters of interest to our shareholders. The feedback we have received has informed and enhanced our ESG disclosures and initiatives.

We greatly value the dialogue we have with our shareholders and remain committed to continued engagement going forward.

Horizon  |  2022 Proxy Statement 10

Summary of Voting Items and Board Recommendations

Horizon  |  2022 Proxy Statement 11

Fostering a Sustainable Future for Horizon, Our Stakeholders and Communities: Key Environmental, Social and Governance (ESG) Factors

Making a difference is ingrained in our corporate culture and integral to our purpose – we go to incredible lengths at Horizon to impact lives and make the world a better place. What we do extends beyond the innovative medicines we deliver; we support patients and their caregivers, physicians, advocacy groups, our communities and beyond. We know that our efforts contribute not just to Horizon’s long-term success and sustainability but also to the broader world.

Key ESG factors that support Horizon’s long-term sustainability include: our governance; our purpose and our focus on ethics and integrity; access to medicines and our patient-centric focus; employee engagement and corporate culture; our product supply chain and environmental sustainability.

Our Governance:

We employ strong corporate governance principles and practices.

Our Purpose and Our Focus on Ethics and Integrity:

We build healthier communities, urgently and responsibly.

Horizon  |  2022 Proxy Statement 12

Access to Medicines and Our Patient-Centric Focus:

We make health a priority, not a privilege.

Our Employee Engagement and Corporate Culture:

For us it’s personal – we want to make a difference and are consistently recognized for our engaged employees.

Horizon  |  2022 Proxy Statement 13

Our Product Supply Chain:

We work stringently to ensure the safety and quality of our medicines.

Environmental Sustainability:

We aim to conduct our business in a responsible way that minimizes environmental impacts.

Horizon Is Consistently Recognized as a Best Place to Work

Horizon  |  2022 Proxy Statement 14

QUESTIONS AND ANSWERS ABOUT THESE PROXY MATERIALS AND VOTING

This Proxy Statement contains important information regarding the Annual General Meeting of Shareholders, the proposals on which you are being asked to vote, information you may find useful in determining how to vote and voting procedures. You are invited to attend the Annual General Meeting to vote on the proposals described in this Proxy Statement. However, you do not need to attend the meeting to vote your shares.

Why did I receive a notice regarding the availability of proxy materials on the internet?

We have sent you a Notice of Internet Availability of Proxy Materials (the Notice) because our Board is soliciting your proxy to vote at the Annual General Meeting, including at any adjournments or postponements of the meeting. As permitted by the U.S. Securities and Exchange Commission, we are making this Proxy Statement, Horizon’s Annual Report to shareholders, and our Irish statutory financial statements available to our shareholders electronically via the internet. We believe that using this form of distribution provides a convenient and expedited method for our shareholders to access the proxy materials and vote, while allowing us to conserve natural resources and reduce the environmental impact of our Annual General Meeting. In addition, it reduces the costs of printing and distributing the proxy materials. Accordingly, we have sent a Notice to our shareholders of record. All shareholders can access the proxy materials on the website referred to in the Notice or may request a printed set of the proxy materials. Instructions on how to access the proxy materials over the internet or to request a print or email copy may be found in the Notice. We intend to mail the Notice on or about March 17, 2022 to all shareholders of record as of February 24, 2022, who are entitled to vote at the Annual General Meeting.

How do I attend the Annual General Meeting?

The meeting will be held on Thursday, April 28, 2022, at 3:00 p.m. local time at our corporate headquarters located at 70 St. Stephen’s Green, Dublin 2, D02 E2X4, Ireland. Directions to the Annual General Meeting may be found at https://www.google.com/maps/place/70+St+Stephen’s+Green,+Saint+Kevin’s,+Dublin,+Ireland. Information on how to vote in person at the Annual General Meeting is provided below. However, you do not need to attend the Annual General Meeting to vote your ordinary shares.

We are closely monitoring developments related to COVID-19. It could become necessary to change the date, time, location and/or means of holding the Annual General Meeting (including by means of remote communication). If such a change is made, we will announce the change in advance, and details on how to participate will be issued by press release, posted on our website and filed as additional proxy materials.

Who can vote at the Annual General Meeting?

Only shareholders of record at the close of business on February 24, 2022, will be entitled to vote at the Annual General Meeting. On this record date, there were 229,167,259 of our ordinary shares outstanding and entitled to vote.

Shareholder of Record (shares registered in your name). If on February 24, 2022 your shares were registered in your name in our Register of Members, which is maintained by our transfer agent, Computershare Shareowner Services LLC, then you are a shareholder of record. As a shareholder of record, you may vote in person at the meeting or vote by proxy. Whether or not you plan to attend the meeting, we urge you to vote by proxy over the telephone or on the internet as instructed in the Notice or as discussed below to ensure your vote is counted, or if you request a printed copy, vote by completing and returning the proxy card.

Beneficial Owner (shares registered in the name of a broker or bank). If on February 24, 2022, your shares were not registered in your name in our Register of Members, but rather held in an account at a brokerage firm, bank, dealer or other similar organization, then you are the beneficial owner of shares held in “street name” and the Notice is being forwarded to you by that organization. The organization holding your account is considered to be the shareholder of record for purposes of voting at the Annual General Meeting. As a beneficial owner, you have the right to direct your broker or other agent regarding how to vote the shares in your account. You are also invited to attend the Annual General Meeting. However, since you are not the shareholder of record, you may not vote your shares in person at the meeting unless you request and obtain a valid proxy from your broker or other agent.

What am I voting on?

There are five matters scheduled for a vote:

Horizon  |  2022 Proxy Statement 15

What if another matter is properly brought before the meeting?

The Board knows of no other matters that will be presented for consideration at the Annual General Meeting. If any other matters are properly brought before the meeting, it is the intention of the persons named in the accompanying proxy to vote on those matters in accordance with their best judgment.

How do I vote?

You may vote “For” or “Against” each Class II director nominee or you may abstain from voting for all or any of the nominees. For each of the other matters to be voted on, you may vote “For” or “Against” or abstain from voting.

The procedures for voting are fairly simple:

Shareholder of Record. If you are a shareholder of record, you may vote in person at the Annual General Meeting, by electronic proxy over the telephone or the internet as instructed below, or by proxy using the proxy card you receive if you request a set of printed materials. Whether or not you plan to attend the meeting, we urge you to vote by proxy to ensure your vote is counted. You may still attend the meeting and vote in person even if you have already voted by proxy.

We provide internet proxy voting to allow you to vote your shares online, with procedures designed to ensure the authenticity and correctness of your proxy vote instructions. However, please be aware that you must bear any costs associated with your internet access, such as usage charges from internet access providers and telephone companies.

Beneficial Owner. If you are a beneficial owner of shares registered in the name of your broker, bank or other agent, you should have received a Notice containing voting instructions from that organization. Simply follow the voting instructions in the Notice to ensure that your vote is counted. Alternatively, you may vote by telephone or through the internet as instructed by your broker, bank or other agent. To vote in person at the Annual General Meeting, you must obtain a valid proxy from your broker, bank or other agent. Follow the instructions in the Notice you receive from your broker, bank or other agent, or contact that organization to request a proxy form.

Joint Holders. In the case of joint holders of record, any one of such holders may vote either in person or by proxy in respect thereof as if he or she were the sole holder thereof, but the vote of the senior holder who tenders a vote, whether in person or by proxy, shall be accepted to the exclusion of the votes of the other joint holders, and for this purpose seniority shall be determined by the order in which the names stand in our Register of Members.

How many votes do I have?

On each matter to be voted upon, you have one vote for each ordinary share you own as of February 24, 2022.

What happens if I do not vote?

Shareholder of Record. If you are a shareholder of record and do not vote by completing your proxy card, by telephone, through the internet or in person at the Annual General Meeting, your shares will not be voted.

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Beneficial Owner. If you are a beneficial owner and do not instruct your broker, bank, or other agent how to vote your shares, the question of whether your broker or nominee will still be able to vote your shares depends on whether the New York Stock Exchange (NYSE) deems the particular proposal to be a “routine” matter. Brokers and nominees can use their discretion to vote “uninstructed” shares with respect to matters that are considered to be “routine,” but not with respect to “non-routine” matters. Under the rules and interpretations of the NYSE, “non-routine” matters are matters that may substantially affect the rights or privileges of shareholders, such as mergers, shareholder proposals, elections of directors (even if not contested), executive compensation (including any advisory shareholder votes on executive compensation) and certain corporate governance proposals, even if management-supported. We have been advised by the NYSE that your broker or nominee may not vote your shares on Proposals 1, 3 or 5 without your instructions, but may vote your shares on Proposals 2 and 4.

What if I return a proxy card or otherwise vote but do not make specific choices?

If you return a signed and dated proxy card or otherwise vote without marking voting selections, then our designated proxy holders (one of the individuals named on your proxy card) will vote your shares in the manner recommended by our Board on all matters presented in this Proxy Statement and as the proxy holders may determine in their discretion regarding any other matters properly presented for a vote at the meeting. If any other matter is properly presented at the meeting, your proxy holder will vote your shares using his or her best judgment.

Who is paying for this proxy solicitation?

We have retained Alliance Advisors, a proxy solicitation firm, to solicit proxies in connection with the Annual General Meeting at a cost of approximately $23,500 plus expenses. The cost of soliciting proxies incurred by us and Alliance Advisors, including the preparation, assembly and mailing of the proxies and soliciting material, as well as the cost of forwarding such material to beneficial owners of our ordinary shares, will be borne by us. Our directors, officers and other employees may, without compensation other than their regular remuneration, solicit proxies personally or by telephone.

What does it mean if I receive more than one Notice?

If you receive more than one Notice, your shares may be registered in more than one name or in different accounts. Please follow the voting instructions on the Notices to ensure that all of your shares are voted.

Can I change my vote after submitting my proxy?

Shareholder of Record. Yes, you may revoke your proxy at any time before the final vote at the meeting. If you are the record holder of your shares, you may revoke your proxy in any one of the following ways:

Your most current proxy card or telephone or internet proxy is the one that is counted.

Beneficial Owner. If your shares are held by your broker or bank as a nominee or agent, you should follow the instructions provided by your broker or bank.

Do I need a ticket to attend the Annual General Meeting?

Yes, you will need an admission ticket or proof of ownership of ordinary shares to enter the Annual General Meeting. If you are a shareholder of record, your admission ticket is the Notice that was sent to you. Please bring your Notice and valid photo identification with you to the Annual General Meeting. If your shares are held in the name of a bank, broker or other holder of record, your admission ticket is your Notice, or if you are a beneficial owner, the ticket is on your voting instruction form. If you do not bring your admission ticket, you will need proof of ownership of ordinary shares to be admitted to the Annual General Meeting. A recent brokerage statement or letter from a bank or broker is an example of proof of ownership. If you arrive at the Annual General Meeting without an admission ticket or proof of ownership of ordinary shares, we will admit you only if we are able to verify that you are one of our shareholders.

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How are votes counted?

Votes will be counted by the inspector of election appointed for the meeting, who will separately count, with respect to the proposal to elect directors, votes “For,” “Against,” abstentions and broker non-votes; and, with respect to other proposals, votes “For” and “Against,” abstentions and, as applicable, broker non-votes. Abstentions and broker non-votes will be treated as shares present for the purpose of determining the presence of a quorum for the transaction of business at the Annual General Meeting. Abstentions and broker non-votes will not, however, be considered votes cast at the Annual General Meeting. Because the approval of all of the proposals is based on the votes cast at the Annual General Meeting, abstentions and broker non-votes will not have any effect on the outcome of voting on the proposals.

What are “broker non-votes”?

As discussed above, when a beneficial owner of shares held in “street name” does not give instructions to the broker or nominee holding the shares as to how to vote on matters deemed by the NYSE to be “non-routine,” the broker or nominee cannot vote the shares. These un-voted shares are counted as “broker non-votes.”

What is the quorum requirement?

A quorum of shareholders is necessary to hold a valid meeting. A quorum will be present if shareholders holding a majority of the issued and outstanding ordinary shares entitled to vote are present at the meeting in person or represented by proxy. On the record date, there were 229,167,259 ordinary shares outstanding and entitled to vote. Thus, the holders of 114,583,630 ordinary shares must be present in person or represented by proxy at the meeting to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your broker, bank or other nominee) or, provided that you are a shareholder of record, if you vote in person at the meeting. Abstentions and broker non-votes will be counted towards the quorum requirement. If there is no quorum, within one hour of the time appointed for the Annual General Meeting, the Annual General Meeting will stand adjourned to May 5, 2022 at 3:00 p.m. local time at the same location, or such other time or place as the Board may determine.

Assuming there is a quorum of shares present at the Annual General Meeting, how many votes are needed to approve each proposal?

How can I find out the results of the voting at the Annual General Meeting?

Preliminary voting results will be announced at the Annual General Meeting. In addition, final voting results will be published in a current report on Form 8-K that we expect to file within four business days after the Annual General Meeting. If final voting results are not available to us in time to file a Form 8-K within four business days after the meeting, we intend to file a Form 8-K to publish preliminary results and, within four business days after the final results are known to us, file an additional Form 8-K to publish the final results.

What are the Irish statutory financial statements?

We are presenting our Irish statutory financial statements, including the reports of the directors and the statutory auditors thereon, at the Annual General Meeting and are making a copy available for download on the Annual Reports / Proxy Statements page in the Investors section of our website (www.horizontherapeutics.com) on or before April 6, 2022. As an Irish company, we are required to prepare Irish statutory financial statements under applicable Irish company law and to deliver those accounts to shareholders of record in connection with our Annual General Meetings. The Irish statutory financial statements cover the results of our operations and financial position for the year ended December 31, 2021.

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Irish law requires the directors to prepare financial statements for each financial year giving a true and fair view of the state of the group’s and parent company’s affairs at the end of the financial year and of the group’s profit or loss for the financial year. Under that law, the directors have prepared the group’s consolidated financial statements in accordance with U.S. accounting standards, as defined in Section 279 of the Irish Companies Act 2014, to the extent that the use of those accounting standards in the preparation of the consolidated financial statements does not contravene any provision of the Irish Companies Act 2014 or of any regulations made thereunder and have prepared Horizon’s parent company’s Irish statutory financial statements in accordance with accounting standards issued by the Financial Reporting Council and promulgated by the Institute of Chartered Accountants in Ireland (Generally Accepted Accounting Practice in Ireland).

What proxy materials are available on the internet?

The Proxy Statement and the Annual Report are available at https://materials.proxyvote.com/G46188. The Irish financial statements will be available in the Investors section of our website (www.horizontherapeutics.com) on or before April 6, 2022. We will mail without charge, upon written request, a copy of these materials to shareholders of record or beneficial owners of our ordinary shares. Requests should be sent to: Horizon Therapeutics plc, Attention: Company Secretary, 70 St. Stephen’s Green, Dublin 2, D02 E2X4, Ireland.

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PROPOSAL 1

ELECTION OF DIRECTORS

The Board is divided into three classes. Each class consists, as nearly as possible, of one-third of the total number of directors and each class has a three-year term. The Board currently consists of nine members, as follows:

The authorized number of directors may be changed only by resolution of the Board. Any additional directorships resulting from an increase in the number of directors will be distributed between the three classes so that, as nearly as possible, each class will consist of one-third of the directors. This classification of the Board may have the effect of delaying or preventing changes in our control or management. Our directors may be removed by ordinary resolution with majority vote of our shareholders at a general meeting provided that notice of such resolution has been given in accordance with Section 146 of the Irish Companies Act 2014. Vacancies on the Board may be filled only by persons elected by a majority of the directors then in office, provided that a quorum is present. A director elected by the Board to fill a vacancy in a class, including vacancies created by an increase in the number of directors, shall serve for the remainder of the full term of that class and until the director’s successor is duly elected and qualified.

Majority Voting: In order to be elected as a director, each nominee must receive the affirmative vote of a majority of the votes cast by the holders of ordinary shares represented at the Annual General Meeting in person or by proxy.

Directors Whose Term of Office Expires in 2022: There are currently three directors in Class II whose term of office expires in 2022. Each of the nominees listed below in Class II is currently a director who was nominated for election by the Board, upon the recommendation of the Nominating and Corporate Governance Committee. If elected, each of these nominees would serve until the 2025 Annual General Meeting of Shareholders and until his or her successor has been duly elected and qualified, or, if sooner, until the director’s death, resignation, disqualification or removal.

The biographical information for our directors that follows is as of March 15, 2022.

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THE BOARD RECOMMENDS

A VOTE IN FAVOR OF EACH NAMED NOMINEE ABOVE

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THE BOARD OF DIRECTORS AND ITS COMMITTEES

In 2021, the Board held six meetings and did not act by unanimous written consent without a meeting. Each Board member attended 100 percent of the aggregate number of meetings of the Board and of the committees on which he or she served that were held during the portion of the last fiscal year for which he or she was a director or committee member. It is our policy to encourage directors and nominees for director to attend annual general meetings of shareholders. All current directors attended our 2021 Annual General Meeting of Shareholders.

The Board is committed to exercising good corporate governance practices. As part of this commitment, the Board regularly monitors developments in corporate governance and reviews processes, policies and procedures in light of such developments. Key information regarding our corporate governance initiatives can be found on our website, www.horizontherapeutics.com, including our Memorandum and Articles of Association, Code of Conduct and Ethics, Corporate Governance Guidelines, and the charters for the Audit, Compensation, Nominating and Corporate Governance and Transaction Committees. The Board believes that its strong corporate governance policies and practices, including the substantial percentage of independent directors on the Board and the robust duties of its lead independent director, empower the Board to effectively oversee our chief executive officer and provide an effective and appropriately balanced Board governance structure.

Other than Mr. Walbert, our chairman, president and chief executive officer, all members of the Board are independent, and all members of committees of the Board are independent. The Board has affirmatively determined that the following eight directors are independent directors within the meaning of the applicable Nasdaq Stock Market (Nasdaq) listing standards: Mr. Daniel, Mr. Grey, Dr. Himawan, Dr. Mahony, Mr. Santini, Dr. Shannon, Mr. Watkins and Ms. Witz. In making these determinations, the Board found that none of these directors or nominees for director had a material or other disqualifying relationship with us. Mr. Walbert is not an independent director by virtue of his current employment with us. To determine independence, the Board reviewed all relevant identified transactions or relationships between each director, or any of his or her family members, and us, our senior management and our independent registered public accounting firm.

As required under applicable Nasdaq listing standards, our independent directors met four times in regularly scheduled executive sessions in 2021, at which only independent directors were present.

We have adopted a Code of Conduct and Ethics (the Code) that applies to all officers, directors and employees, including our principal executive officer, principal financial officer, principal accounting officer and persons performing similar functions. We introduced a revised, principles-based Code in 2021 that provides an instructive set of principles, guidelines and tools to operate our business in an ethical and compliant way. In addition to promptly publishing the revised Code on our website, we conducted employee training, including 45 live sessions, on the revised Code, with 100 percent participation. The Code is available in the investor relations section of our website at www.horizontherapeutics.com. If we make any substantive amendments to the Code or grant any waiver from a provision of the Code to any executive officer or director, we will promptly disclose the nature of the amendment or waiver on our website or in a current report on Form 8-K.

The Board has determined that the current leadership structure, in which the offices of chairman and chief executive officer are held by one individual and an independent director acts as lead independent director, ensures that the appropriate level of oversight, independence and responsibility is applied to all Board decisions, including risk oversight, and is in our best interests and those of our shareholders.

Chairman/Chief Executive Officer

The Board is currently chaired by our president and chief executive officer, Mr. Walbert. We believe that combining the positions of chief executive officer and chairman of the Board helps to ensure that the Board and management act with a common purpose for the following reasons:

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Lead Independent Director

We require the election, by the independent directors of the Board, of a lead independent director to serve during any period when there is no independent chairman of the Board. Because Mr. Walbert is currently serving as chief executive officer and chairman of the Board, the independent directors of the Board elected Mr. Grey as the lead independent director. The lead independent director serves as the liaison between the chairman of the Board and the independent directors. The responsibilities of the lead independent director include:

One of the Board’s key functions is informed oversight of our risk management process. The Board does not have a standing risk management committee, but rather administers this oversight function directly through the Board as a whole, as well as through various Board standing committees that address risks inherent in their respective areas of oversight. In particular, the Board is responsible for monitoring and assessing strategic risk exposure, including a determination of the nature and level of risk appropriate for Horizon.

Our Audit Committee has the responsibility to consider and discuss our major financial risk exposures and the steps our management has taken to monitor and control these exposures, including guidelines and policies to govern the process by which financial risk assessment and management is undertaken and provides oversight of the performance of our internal audit function and external auditors. The Audit Committee also reviews and receives regular briefings concerning information security and technology risks.

Our Nominating and Corporate Governance Committee reviews our key enterprise risks and risk-management strategies, as well as monitors the effectiveness of our corporate governance guidelines, including whether they are successful in preventing illegal or improper liability-creating conduct, and monitors compliance with legal, regulatory and ethical requirements.

Our Compensation Committee assesses and monitors whether any of our compensation policies and programs has the potential to encourage excessive risk-taking.

Our Transaction Committee evaluates potential strategic transactions and financing opportunities, including the risks that such transactions could pose to Horizon.

Cybersecurity

Horizon is committed to protecting our company’s information technology systems. We manage information technology (IT) systems that facilitate commercial, supply chain and regulatory activities; maintain our financial data; and store employee and customer data. We have protocols, policies and tools in place to mitigate cybersecurity risk. They also provide the administrative, technical, and physical safeguards to ensure the security, confidentiality, integrity and availability of confidential information and personal information from unauthorized access, use, disclosure, alteration, destruction or theft. In addition, we engage an independent third party annually to assess our IT general controls and IT security.

The Audit Committee and full Board is briefed by our chief information officer at least twice a year on our cybersecurity risk management programs and the overall cybersecurity risk environment. The briefing includes discussions on topics such as information security and technology risks, cybersecurity, information risk management strategies and progress and cybersecurity and data protection training initiatives for employees, among others. To our knowledge, we have not experienced a material information security breach nor incurred any penalties or settlements regarding information security.

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The Nominating and Corporate Governance Committee believes that a strong director assessment process and periodic Board refreshment enhances the effectiveness of the Board and is an essential element of sound corporate governance.

Director assessment is conducted on an annual basis at both the full Board and individual director level:

Annual Board Member Self-Assessment: The director self-assessment process typically begins in August, when a telephonic survey is conducted with each director by a third party, generally a partner from our external legal counsel. The telephonic survey, which is updated annually, allows the interviewer to more fully assess and understand the needs, comments and patterns resulting from the individual conversations. This interview process elicits each director’s opinions on the overall effectiveness of the Board and its committees, the information the Board receives, the conduct of Board meetings, communication among directors and management, the oversight of key business risks and environmental, social and governance issues, Board composition, and any other matters that any director wishes to raise. The results are summarized in an anonymous matter and reviewed by the Nominating and Corporate Governance Committee during its fourth-quarter meeting and key findings and observations are reported to the full Board for discussion and action, if appropriate. This process has resulted in several meaningful improvements to the effectiveness of our Board meetings and timing and means of providing information to the Board.

Annual Board Member Review: A thorough and in-depth review is conducted for the directors whose term will expire at the next annual general meeting of shareholders. The review assesses each director based on his or her Board and committee experience to date and the skills and experiences deemed appropriate to meet the current and future needs of Horizon and the Board. The review consists of a three-part process to determine if each director should seek another three-year term.

As a result of our Board assessment process, since 2017, two prior directors did not stand for re-election and three new directors have been added to the Board. Each of our new directors, two of whom are female, have brought new and different skills, experience and qualifications to the Board. This refreshment of the Board serves to better meet the current and expected future needs of Horizon given the evolution of our business and strategy over the last several years.

The Nominating and Corporate Governance Committee employs a rigorous, thorough and in-depth process to identify director candidates and recommend the strongest possible director nominees to the full Board.

First, the Nominating and Corporate Governance Committee deliberates on and determine the skills and experience that would best serve the Board and Horizon and that would address any gaps identified in the annual assessment process.

An executive search firm is then retained to assist in identifying prospective candidates. In addition, the Nominating and Corporate Governance Committee considers director candidates recommended by shareholders, directors and other sources.

When selecting candidates for recommendation to the Board, the Nominating and Corporate Governance Committee consider the attributes of the candidates and the needs of the Board and reviews all candidates in the same manner, regardless of the source of the recommendation. In evaluating director nominees, a candidate is expected to have certain minimum qualifications, including being able to read and understand basic financial statements, having familiarity with our business and industry, having high moral character and mature judgment and being able to work collegially with others. In addition, factors such as the following may be considered:

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Before the Nominating and Corporate Governance Committee recommends a qualified director nominee to the Board for consideration, the nominee is interviewed by each Board member and meets with the chief executive officer and other senior executives.

The Nominating and Corporate Governance Committee and the Board believe that all directors should have sufficient time and attention to devote to Board duties and to otherwise fulfill the responsibilities required of directors. In assessing whether directors and nominees for director have sufficient time and attention to devote to Board duties, the Nominating and Corporate Governance Committee considers, among other things, whether directors may be “overboarded,” which refers to the situation where a director serves on an excessive number of boards. Our Corporate Governance Guidelines also require that non-employee directors seek approval from the Chairman or the lead independent director in advance of accepting an invitation to serve on any additional corporate boards or board committee of another company. Management members of the Board must advise the lead independent director and consult with the Chair of the Nominating and Corporate Governance Committee in advance of accepting an invitation to serve on the board of another company and should only do so to the extent such service would not detract from his or her ability to fulfill his or her management functions at the Company. The Nominating and Corporate Governance Committee and our Board believe that each of our directors has demonstrated the ability to devote sufficient time and attention to Board duties and to otherwise fulfill the responsibilities required of directors.

The Board believes that maintaining a diverse membership enhances the Board’s deliberations and enables the Board to better represent all of Horizon’s constituents, and as such has a formal diversity policy. As part of the policy, the Nominating and Corporate Governance Committee annually reviews the tenure, performance and contributions of existing Board members to the extent they are candidates for re-election and considers all aspects of each candidate’s qualifications and skills with the goal of ensuring the Board has diversity of experience and perspectives as well as race, gender, geography, and areas of expertise. To further this goal, the Board is committed to including in each director search highly qualified candidates who reflect diverse experiences and backgrounds, including diversity of gender and race. The diversity policy is available on our website at www.horizontherapeutics.com.

Shareholders who wish to recommend individuals for consideration by the Nominating and Corporate Governance Committee to become nominees for election to the Board at an Annual General Meeting of Shareholders must do so by delivering a written recommendation to the Nominating and Corporate Governance Committee. See “Other Information – Shareholder Proposals” in this Proxy Statement for additional information.

A key responsibility of the Board and critical to our success is ensuring that Horizon has the continuity of leadership and appropriate talent to lead the company and drive the execution of our strategy. We have a robust succession planning process, overseen by the Nominating and Corporate Governance Committee, which facilitates periodic Board executive sessions to discuss succession and development matters. On an annual basis, the Nominating and Corporate Governance Committee reviews and approves the succession and development plans for our chief executive officer, which includes selection criteria and the evaluation of potential internal candidates. In addition, the Nominating and Corporate Governance Committee reviews succession plans of other members of executive management, as well as their attributes, qualifications and development plans.

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In November 2021, Paul Hoelscher, our executive vice president, chief financial officer (CFO), notified us of his intention to retire in May 2022, continuing on as an advisor through May 2023 to ensure a smooth transition. Mr. Hoelscher, who has served as our CFO since 2014, will be succeeded by Aaron Cox, executive vice president, finance, who has been with Horizon since 2016. The process followed for Mr. Hoelscher’s leadership succession planning, as well as the transition period, illustrates the value of our robust succession planning process for the CFO role over the past several years. Mr. Cox, with his extensive knowledge of our business and his strong financial background, is well equipped to succeed Mr. Hoelscher: during his tenure with Horizon, he has been a leader in many of our major strategic efforts, including corporate development, and he has led our capital markets initiatives.

The Board is also regularly apprised of high-leadership potential candidates at Horizon and the plans for their development and potential roles. Board members have the chance to meet with these individuals at Board meetings, at dinners with Board members or in individual meetings as appropriate. We arrange for Board members to meet with key talent when they visit our offices. At each Board meeting, our chief human resources and chief diversity officer updates the Board on different key human capital management matters such as diversity, equity and inclusion, recruitment, development and retention. The Board also reviews our annual employee surveys and is briefed on the responses and targeted actions generated from the survey results.

The Board has four standing committees:

All committees comprise independent directors within the meaning of the applicable Nasdaq listing standards. A description of each committee of the Board is provided below.

The following table provides membership and meeting information for 2021 for each of the Board committees:

Audit

Compensation

Nominating and Corporate Governance

Transaction

Timothy P. Walbert

William F. Daniel

Michael Grey ( )

Jeff Himawan, Ph.D. (1)

Susan Mahony, Ph.D.(2)

Gino Santini(3)

James Shannon, M.D.(4)

H. Thomas Watkins

Pascale Witz

Total meetings in 2021

5

8

4

5

= Chair		= Member		= Lead Independent Director

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Audit Committee

The Audit Committee assists the Board in fulfilling its oversight responsibility with respect to, among other things:

The independent registered public accounting firm, internal audit and management each periodically meet privately with the Audit Committee.

The Board has determined that each of Mr. Daniel, Mr. Grey, Mr. Watkins and Ms. Witz qualify as “audit committee financial experts” within the meaning of applicable SEC rules. In making this determination, the Board has considered their formal education, the nature and scope of their previous experience and their financial and corporate governance expertise.

Report of the Audit Committee of the Board of Directors

The material in this report is not “soliciting material,” is not deemed “filed” with the SEC and is not to be incorporated by reference in any of our filings under the Securities Act of 1933, as amended (the Securities Act), or the Securities Exchange Act of 1934, as amended (Exchange Act), whether made before or after the date hereof and irrespective of any general incorporation language in any such filing.

The Audit Committee has reviewed and discussed the audited financial statements for the year ended December 31, 2021, with Horizon management. The Audit Committee has discussed with the independent registered public accounting firm the matters required to be discussed by Auditing Standard No. 1301, Communications with Audit Committees, as adopted by the Public Company Accounting Oversight Board (PCAOB). The Audit Committee has also received the written disclosures and the letter from the independent registered public accounting firm required by applicable requirements of the PCAOB regarding the independent registered public accounting firm’s communications with the Audit Committee concerning independence and has discussed with the independent registered public accounting firm the accounting firm’s independence. Based on the foregoing, the Audit Committee has recommended to the Board that the audited financial statements be included in Horizon’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021.

Audit Committee

William F. Daniel, Chair

Michael Grey

H. Thomas Watkins

Pascale Witz

Compensation Committee

The Compensation Committee:

In making its compensation decisions and recommendations, the Compensation Committee may take into account the recommendations of the chief executive officer and other senior management. Other than giving such recommendations, however, the chief executive officer and other senior management have no formal role and no authority to determine the amount or form of executive and director compensation. The processes and procedures used by the Compensation Committee for the consideration and determination of executive compensation are described in the section of this Proxy Statement captioned, ‘‘Compensation Discussion and Analysis – Compensation Determination Process.’’

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The Compensation Committee may, at our expense, retain legal counsel (which may, but need not be, our regular corporate counsel) and other consultants and advisors, other than in-house legal counsel and certain other types of advisors, to assist it with its functions only after taking into consideration six factors, prescribed by the SEC and Nasdaq, that bear upon the advisor’s independence; however, there is no requirement that any advisor be independent. The Compensation Committee has authority to approve such advisors’ fees and other retention terms and to terminate its relationship with any advisor that it retains. In addition, the Compensation Committee has authority to delegate its responsibilities to subcommittees or individual committee members.

The Compensation Committee has engaged Aon’s Human Capital Solutions practice, a division of Aon plc (Aon), as its independent consultant since 2016. For additional information regarding our processes and procedures for the consideration and determination of executive and director compensation, including the role of Aon in determining and recommending executive and director compensation and the aggregate cost of Aon’s executive and director compensation consulting services during 2021, see the sections of this Proxy Statement entitled “Compensation Discussion and Analysis – Compensation Determination Process” and “Non-Employee Director Compensation.” With respect to non-employee director compensation matters, our Compensation Committee recommends to our Board and our Board determines and sets non-employee director compensation. Our compensation arrangements for our non-employee directors are described under the section of this Proxy Statement entitled “Non-Employee Director Compensation.”

Compensation Committee Interlocks and Insider Participation

No member of our Compensation Committee has ever been an executive officer or employee of Horizon. None of our executive officers currently serves, or has served during the last completed year, on the compensation committee or board of directors of any other entity that has one or more officers serving as a member of our Board or Compensation Committee.

Nominating and Corporate Governance Committee

The Nominating and Corporate Governance Committee oversees all aspects of our corporate governance functions on behalf of the Board, including, but not limited to:

The process used by the Nominating and Corporate Governance Committee to identify a nominee to serve as a member of the Board depends on the qualities being sought. The Board engages an executive search firm to assist the Nominating and Corporate Governance Committee in identifying individuals qualified to be Board members. The process used by the Nominating and Corporate Governance Committee to identify nominees is described in the section of this Proxy Statement captioned, ‘‘Director Selection.”’

Transaction Committee

The functions of the Transaction Committee include, but are not limited to:

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Shareholders who wish to communicate with the Board may do so by sending written communications addressed to the Company Secretary of Horizon Therapeutics plc at 70 St. Stephen’s Green, Dublin 2, D02 E2X4, Ireland or by communicating online to the Board as a group. This information and an online communications form are available on our website at www.horizontherapeutics.com. Each communication will be reviewed by our Company Secretary to determine whether it is appropriate for presentation to the Board or such director on a periodic basis. Examples of inappropriate communications include advertisements, solicitations or hostile communications.

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NON-EMPLOYEE DIRECTOR COMPENSATION

Our directors perform a critical role in guiding Horizon’s strategic direction and overseeing management. Being a director entails many responsibilities and a substantial time commitment. Our compensation program for our non-employee directors reflects the critical function they perform and enables us to attract and retain highly qualified directors.

All current non-employee members of the Board are independent. Non-employee directors receive a combination of annual cash retainers and restricted stock unit (RSU) grants in amounts that correlate to their responsibilities and levels of Board participation, including service on Board committees. Our only employee director, Mr. Walbert, receives no separate compensation for his service as a director or chair.

Highlights

Peer Groups

As an Irish headquartered company traded in the United States, we consider our non-employee director compensation, both in amount and structure, against two peer groups:

Alkermes plc and Jazz Pharmaceuticals plc are in both peer groups.

Compensation Program

The Compensation Committee reviews the compensation for our non-employee directors annually. To assist with the review, Aon, an independent compensation consultant, prepares a comprehensive assessment of our non-employee director compensation program, which includes:

As part of the most recent review, conducted in October 2021, the Compensation Committee determined that:

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As a result of this review, in October 2021, the Compensation Committee amended our compensation policy for non-employee directors to provide that the annual cash compensation paid to the members of our Nominating and Corporate Governance Committee and to the chair of our Nominating and Corporate Governance Committee would be $10,000 and $20,000, respectively.

Cash Compensation

Our compensation policy for non-employee directors who are not affiliated with any holder of more than 5 percent of our ordinary shares provides for annual cash compensation as set forth in the following table. The cash compensation is generally payable in equal quarterly installments at the end of each quarter in which the services are provided. For any independent director who joins after the beginning of the quarter, the cash compensation is pro-rated based on days served in that first partial quarter.

Under our compensation policy, we reimburse our directors for their travel-related expenses, including lodging and other reasonable expenses incurred in attending meetings of the Board and committees of the Board.

We also reimburse eligible non-employee directors up to $15,000 annually for financial planning and tax services.

Equity Compensation

On the date of each Annual General Meeting of Shareholders that coincides with or follows the non-employee director’s initial appointment or election to the Board, eligible non-employee directors will automatically be granted RSUs with an aggregate value of $400,000, which will vest in full upon the earlier of the (i) first anniversary of the date of grant and (ii) date of the next Annual General Meeting of Shareholders.

Any eligible non-employee director who is first elected or appointed to the Board on any date other than an Annual General Meeting of Shareholders will automatically be granted RSUs on the date that they are first elected or appointed to the Board with a value equal to the annual RSU grant, prorated based on the number of days between such non-employee director’s start date and the one-year anniversary of the date of the Annual General Meeting of Shareholders that most recently preceded such start date, which will vest in full upon the earlier of (i) the first anniversary of the date of the Annual General Meeting of Shareholders that most recently preceded such director’s start date and (ii) the date of the next Annual General Meeting of Shareholders.

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Non-Employee Director Compensation Summary

The following table sets forth compensation information for our non-employee directors who earned or received compensation under our compensation policy for non-employee directors or otherwise in 2021:

Non-Employee Director Share Ownership Guidelines

We have share ownership guidelines for our non-employee directors. The share ownership guidelines were amended in October 2021 and require that each director accumulate an ownership interest in our ordinary shares with a value equal to at least 5x the annual cash board service retainer within five years of the date the non-employee director first becomes subject to the guidelines.

Individual ownership interest versus the guidelines is reviewed annually using an average share price for a calendar quarter prior to the review date. Shares that count toward satisfaction of these guidelines include: shares owned outright by the individual (including stock units that have vested but not yet settled); shares subject to RSUs that have not vested; and shares held in trust for the benefit of the individual or his/her spouse.

All of our non-employee directors subject to the share ownership guidelines met the guidelines as of March 31, 2021.

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EXECUTIVE OFFICERS AND SIGNIFICANT EMPLOYEES

The following table sets forth information regarding executive officers and significant employees as of March 15, 2022:

The following biographical information for our executive officers and significant employees other than Mr. Walbert, whose biographical information is included in Proposal 1, is as of March 15, 2022.

Executive Officers

Sean M. Clayton. Mr. Clayton has served as our executive vice president, general counsel since February 2022. Prior to joining Horizon, Mr. Clayton was a partner at Cooley LLP, a global law firm, where he practiced from October 2004 until February 2022, most recently as the head of the firm’s San Diego corporate practice. Before that, Mr. Clayton served as a law clerk to Judge Irma E. Gonzalez (Ret.) of the U.S. District Court for the Southern District of California. Mr. Clayton received a bachelor of arts degree in political science and economics from the University of California, San Diego and a juris doctorate degree from Stanford Law School.

Michael A. DesJardin. Mr. DesJardin has served as our executive vice president, technical operations and corporate quality since February 2017. Mr. DesJardin previously served as our senior vice president, technical operations from October 2016 to November 2016 and as our senior vice president, life cycle management from December 2016 to January 2017. Mr. DesJardin joined Horizon from Raptor in October 2016 as part of the Raptor acquisition. While at Raptor, Mr. DesJardin was the senior vice president of technical operations from April 2015 to October 2016. Prior to that, Mr. DesJardin served as senior vice president of product development at Jazz Pharmaceuticals plc (formerly Jazz Pharmaceuticals, Inc.) (Jazz) from July 2004 to March 2015. Mr. DesJardin spent nine years as an executive director and engineering fellow at ALZA Corporation and spent 15 years at the Dow Chemical Company working in pharmaceutical and agricultural chemical development for Marion Merrill Dow. Mr. DesJardin has over 40 years of experience in pharmaceutical development. Mr. DesJardin received a bachelor of science degree in chemical engineering from the University of California, Berkeley, and is a registered professional engineer in the State of California.

Paul W. Hoelscher. Mr. Hoelscher has served as our executive vice president, chief financial officer since October 2014. Previously, Mr. Hoelscher was our executive vice president, finance from June 2014 through September 2014. Prior to joining Horizon, Mr. Hoelscher served as senior vice president, finance-treasury and corporate development of OfficeMax, Inc., from August 2013 to May 2014, and as vice president, finance-treasury and corporate development of OfficeMax from August 2012 to July 2013. Prior to that, Mr. Hoelscher served in various finance roles at Alberto Culver Company from 1992 to 2012 and in various positions in the audit practice at KPMG LLP from 1986 to 1993. He serves on the board of Reneo Pharmaceuticals, Inc., a public pharmaceutical company; on the board of trustees of the Illinois Region of The Leukemia and Lymphoma Society and on the Chicago Regional Advisory Committee of the Ireland Funds. Mr. Hoelscher received his bachelor of science degree in accountancy from the University of Illinois at Urbana-Champaign and is a certified public accountant.

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Andy Pasternak. Mr. Pasternak has served as our executive vice president, chief strategy officer since March 2020 and previously served as our executive vice president, chief business officer from November 2019 until March 2020. Prior to joining Horizon, Mr. Pasternak served as a partner of Bain & Company, Inc., a global management consulting firm, from 2008 until October 2019, where he most recently led Bain & Company’s healthcare practice in the Americas and was a member of the mergers and acquisition practice. Mr. Pasternak earned a master of business administration degree from the University of Chicago and a bachelor of arts degree in economics from Northwestern University.

Jeffrey W. Sherman, M.D., FACP. Dr. Sherman has served as our executive vice president, chief medical officer since January 2018. From September 2014 to January 2018, Dr. Sherman served as our executive vice president, research and development and chief medical officer. He joined Horizon in 2009 as our executive vice president, development, manufacturing, regulatory affairs and chief medical officer. Prior to joining Horizon, Dr. Sherman served as president and board member of the Drug Information Association (DIA), a nonprofit professional association of members who work in government regulatory, academia, patient advocacy and the pharmaceutical and medical device industry. Before that he held other management roles at IDM Pharma, Inc., Takeda Global Research & Development, NeoPharm, Inc. and G.D. Searle, LLC/Pharmacia. Dr. Sherman serves on the board of directors of Xeris BioPharma Holdings, previously two public biopharma companies, Strongbridge Biopharma plc (Stonebridge) and Xeris Pharmaceuticals Inc. (Xeris) until October 2021, when Xeris acquired Strongbridge. Dr. Sherman previously served on the boards of directors of both Strongbridge and Xeris. He also serves on the board of directors of the Biotechnology Innovation Organization (BIO) Health Section Governing Board and the board of advisors of the Center for Information and Study on Clinical Research Participation (CISCRP). He is an adjunct assistant professor of Medicine at the Northwestern University Feinberg School of Medicine and a diplomat of the National Board of Medical Examiners and the American Board of Internal Medicine. Dr. Sherman received his medical degree from the Rosalind Franklin University/ Chicago Medical School.

Elizabeth H.Z. Thompson, Ph.D. Dr. Thompson has served as our executive vice president, research and development since March 2021. Previously she served as our group vice president, development and external search from January 2020 to March 2021, and as our vice president, clinical development (rare disease) from June 2018 to January 2020. Prior to joining Horizon, she was with AbbVie as group scientific director, clinical development from April 2017 to May 2018 and senior scientific director, clinical development, from September 2015 to April 2017. While at AbbVie, she was the clinical lead for risankizumab (SKYRIZI), supporting global submissions and approvals. Before AbbVie, Dr. Thompson held roles at Raptor, InterMune and Amgen in a career spanning clinical development, business development and medical communications. Dr. Thompson received a bachelor of science degree in chemistry from Harvey Mudd College and a doctorate in macromolecular and cellular structure and chemistry from The Scripps Research Institute.

Significant Employees

Aaron L. Cox. Mr. Cox has served as our executive vice president, finance since November 2021. Mr. Cox previously was senior vice president, corporate development, in addition to serving as chief of staff for Timothy P. Walbert, from July 2017 to November 2021; as senior director, business development, from May 2017 to July 2017 and as director, business development from April 2016 to May 2017. Prior to joining Horizon in April 2016, Mr. Cox served as vice president, capital markets at BMO Capital Markets from July 2012 to April 2016, and before that, he held investment banking roles at Stout from 2007 to 2010 and JMP Securities from 2005 to 2006. Mr. Cox received a master of business administration from the University of Chicago and a bachelor of business administration in finance from the University of Notre Dame.

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COMPENSATION DISCUSSION AND ANALYSIS

This Compensation Discussion and Analysis (CD&A) discusses the compensation philosophy, policies and principles underlying our executive compensation decisions made for 2021 compensation. This CD&A provides qualitative information on the factors relevant to these decisions and the manner in which compensation is awarded to the following executive officers who have been named in the Summary Compensation Table included in this Proxy Statement and whom we refer to as our named executive officers (NEOs).

Quick CD&A Reference Guide

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2021 – Year at a Glance

Net sales and adjusted EBITDA growth percentages represent year-over-year growth over full-year 2020.

EBITDA: Earnings before interest, taxes, depreciation and amortization. | TSR: Total shareholder return through December 31, 2021. | NBI: Nasdaq Biotechnology Index.

Prior TSR results are not intended to forecast or be indicative of possible future performance of our ordinary shares.

A Milestone Year in Our Transformation

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For additional discussion about our business, our key differentiators, our pipeline and our key growth drivers TEPEZZA, KRYSTEXXA and UPLIZNA, see the discussion under the heading “Business Overview” in the Proxy Statement Summary on page 3.

Total Shareholder Return

Our disciplined approach, clear strategy, business development capabilities and strong commercial and R&D execution have all worked together to generate consistent above-market returns for our shareholders. Our TSR significantly outperformed both our peer group and the NBI over the one-, three- and five-year periods ended December 31, 2021. With our expanded pipeline and key growth medicines, we believe Horizon is well positioned for sustainable long-term growth.

Our Total Shareholder Returns Significantly Exceed Our Peers⁽¹⁾ and the NBI

1-, 3- and 5-Year Periods Ended December 31, 2021

Our Pay Program

Our executive compensation program continues to be based on attracting and retaining top talent with experience in building and leading a successful rare disease biotech company, while providing competitive compensation and benefits packages that create a direct, meaningful link between business results and compensation opportunities. In doing so, we believe our thoughtful approach aligns the interests of management, employees, patients, shareholders and other stakeholders in setting priorities and executing our long-term business strategy.

Say-on-Pay Results and Shareholder Engagement

We value the views of our shareholders and we continue to have significant and meaningful engagement each year with our shareholders regarding our compensation and governance practices, generally led by a member of the Board of Directors, and we plan to continue this practice. Our shareholder outreach and engagement program is used to solicit feedback, understand investor viewpoints and incorporate their feedback into future evaluations of our compensation program. In particular, feedback from these outreach efforts informs the Compensation Committee’s thinking when evaluating our current executive compensation program and when considering potential modifications to the program on a go-forward basis.

During our shareholder engagement cycle before our 2021 Annual General Meeting of Shareholders, as well as during our off-season shareholder engagement cycle in late 2021 and early 2022, we offered engagement opportunities to shareholders who represented approximately 60 percent of our shares outstanding. Shareholder feedback from our most recent engagement efforts was positive. At our 2021 Annual General Meeting of Shareholders, our say-on-pay proposal received the support of approximately 96 percent of the shares voted. We believe this high level of support is a result of our appropriately designed executive compensation program, which is designed to pay for performance, as well as our comprehensive shareholder outreach and engagement program.

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Changes to our compensation program over the past several years that were heavily influenced by shareholder feedback include:

We greatly value the dialogue we have with our shareholders and remain committed to conducting consistent engagement going forward.

2021 Pay-for-Performance Overview

A significant portion of total target compensation for our chief executive officer (CEO) and other NEOs is structured in the form of “at-risk” compensation, consisting of annual performance-based incentives and PSUs.

In line with our compensation objectives, including linking executive pay with performance, short-term performance-based incentives and PSUs are dependent on Horizon’s performance, aligning our executives’ interests with those of our shareholders for near- and long-term performance. In addition, the restricted share unit (RSU) portion of the total target compensation has a time-based vesting component so that the total potential value realized from the RSU portion is dependent on our long-term share price performance.

Total target compensation for 2021, as shown below, consists of annual base salary, target annual bonus, and target PSU and RSU grant values. Approximately 56 percent of our CEO’s total target compensation for 2021 was tied to the achievement of pre-established performance goals, with time-based equity awards making up approximately 38 percent of the total.

CEO 2021 Pay Mix at Target		NEO 2021 Pay Mix at Target

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Compensation Program and Governance

Our Compensation Committee is responsible for oversight of our executive compensation program. A significant part of this oversight entails aligning management interests with our business strategies and goals, as well as the interests of our shareholders, employees and patients, while also mitigating excessive risk-taking. We continually take steps to strengthen and improve our executive compensation policies and practices. Highlights of our current policies and practices include:

We believe in providing a competitive total compensation package to our executive officers through a combination of base salary, short-term performance-based cash incentives, long-term performance-based equity incentives, and severance and change-in-control benefits. Our executive compensation program is designed to achieve the following objectives:

Our Compensation Committee believes that our executive compensation program should include short- and long-term performance incentive components, including cash and equity-based compensation, and should reward consistent performance

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that meets or exceeds expectations. The Compensation Committee evaluates both performance and compensation to make sure that the total compensation provided to our executive officers remains competitive relative to compensation paid by companies of similar size and stage of development that operate in the biotech industry and appropriately reflects our relative performance and our own strategic objectives.

Role of Compensation Committee

The Compensation Committee seeks to ensure that our executive compensation program is properly rewarding and motivating our executive officers while aligning their goals with our business strategy and the interests of our shareholders. To do this, our Compensation Committee conducts an annual review of the aggregate level of our executive compensation, the mix of elements used to compensate our executive officers and historic compensation levels, including prior equity awards.

When setting executive compensation opportunities, the Compensation Committee considers several factors, including:

Role of Chief Executive Officer in Compensation Decisions

Our CEO typically evaluates the performance of other executive officers and other employees, along with the performance of the Company as a whole, against previously determined objectives, on an annual basis and makes recommendations to the Compensation Committee with respect to annual base salary adjustments, short-term performance-based cash incentives and annual equity grants for the other executives. The Compensation Committee exercises its own independent discretion in approving compensation for all executive officers and assessing corporate performance against the pre-established objectives. The CEO is not present during deliberations or voting with respect to his own compensation.

Risk Analysis

The Compensation Committee has reviewed our compensation policies applicable to our executive officers and other employees and believes that our policies do not encourage excessive and unnecessary risk-taking, and that the level of risk that they do encourage is not reasonably likely to have a material adverse effect on us. The design of our compensation policies and programs encourages our executive officers and other employees to remain focused on both our short- and long-term goals. For example, while our short-term incentive plan (our annual bonus plan) measures performance on an annual basis, our long-term incentive equity grants, which consist of time-based equity awards (RSUs) and performance-based equity awards (PSUs) vest over a number of years. Furthermore, our PSUs require that we achieve a specified level of performance over multi-year periods, which we believe encourages our executives and employees to focus on execution of our long-term strategy, thus limiting the potential value of excessive risk-taking.

Role of Independent Consultant

The Compensation Committee retains the services of third-party, independent executive compensation consultants from time to time, as it sees fit, in connection with the establishment of compensation programs and related policies. The Compensation Committee has engaged Aon’s Human Capital Solutions practice, a division of Aon plc (Aon), as its independent consultant since 2016. Total fees paid to Aon in 2021 were approximately $652,000. Aon was engaged to assist and advise on all aspects of compensation program design and pay setting, including, but not limited to, the following services:

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The Compensation Committee periodically assesses the independence of Aon under the applicable SEC and Nasdaq standards.

Peer Group

Although our Compensation Committee has historically used survey data from Aon as a tool in determining executive compensation, it typically has not used a formula or “benchmark” to set our executives’ compensation in relation to this data. Instead, the Compensation Committee generally references the 50^th percentile of comparable peer companies in combination with multiple other factors, such as the executives’ respective levels of experience, tenure and responsibility in determining the total target compensation for all executives. The peer group used for making 2021 compensation decisions and comparative performance analysis is shown below and was updated by our Compensation Committee in July 2020, with a focus on publicly traded commercial biotech and pharmaceutical companies.

The selection criteria used, as well as Horizon’s position relative to each criterion at the time of the peer group review process, were:

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Our executive compensation program primarily consists of base salary, annual cash incentives and long-term incentives delivered through equity and cash awards. Employees in more senior roles have an increasing proportion of their total pay package at risk and tied to performance given that their position has greater influence on our performance results.

2021 Executive Compensation at a Glance

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“Variable” compensation is compensation in which the ultimate value received is contingent either 1) on performance, typically measured as financial, operational, or stock price performance, such as for PSUs or 2) on the stock price value at the vesting date, such as for RSUs.

Base Salary

Base salaries for our executive officers are established based on the individual’s scope of responsibilities, experience and market factors. Base salaries are generally reviewed annually, typically in connection with our annual executive compensation review process. The Compensation Committee references survey and peer group data to understand the marketplace for individuals in similar positions at the peer group companies. Based on the survey and peer group data, the Compensation Committee determined that a 3.5 percent increase to the base salaries of our NEOs, with the exception of Mr. Hoelscher, was appropriate and was consistent with industry trends. Mr. Hoelscher received a more significant increase to his base salary, 9.3 percent, to reflect his broader responsibilities and contribution, as well as to align his base salary more closely with market data and other Horizon executives.

The annual base salaries of our NEOs as of March 1, 2021, and the increase from their prior base salary levels, were as follows:

Short-Term Incentives: Annual Bonus Plan

Individual Performance-Based Bonus Opportunities

We provide performance-based cash annual bonuses as an incentive for our executives to achieve defined, corporate financial goals, as well as certain corporate strategic objectives. These bonuses may range in payout from 0 percent to 200 percent of targeted payout levels.

The general structure of this program has remained unchanged since 2014. The 2021 target bonus opportunities as a percentage of base salary for our NEOs, which remained unchanged from 2020, were as follows:

Our annual bonus plan provides our executives the opportunity to earn performance-based cash awards based on the achievement of a combination of financial goals (60 percent weighting) and strategic goals (40 percent weighting). The Compensation Committee increased the strategic goal weighting component of the annual bonus plan for 2021 by 5 percent, resulting in a weighting of 40 percent, to provide additional incentives for achieving the broader scope of the Integration, Strategy and Financing Initiatives goal to include integration initiatives.

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Timing Considerations in Establishing the 2021 Financial Goals and Strategic Goals

While the Compensation Committee has generally finalized annual bonus plan goals in February, two significant contingencies influenced the timing of the establishment of the final 2021 financial and strategic goals. In mid-December 2020, we experienced a supply disruption of TEPEZZA due to U.S. government-mandated COVID-19 vaccine production orders. At that time, we anticipated that the supply shortage of TEPEZZA could continue throughout the first quarter of 2021. In addition, on February 1, 2021, we announced that we had entered into a definitive agreement to acquire Viela Bio. At the time, the transaction was expected to close by the end of the first quarter of 2021. Given these two developments, which were each expected to have a significant impact on 2021 goals, in accordance with provisions of the annual bonus plan program, the Compensation Committee determined to defer finalization of the annual bonus program goals until April 2021, by which time the Viela transaction was expected to have closed and supply of TEPEZZA was expected to have resumed.

The Viela acquisition was completed in mid-March 2021, and in late March we announced that we would be able to resume supply of TEPEZZA beginning in April. In April 2021, after considering factors associated with the Viela acquisition and the TEPEZZA supply disruption and reviewing the financial impact of both developments on our projected full-year 2021 net sales and internal adjusted earnings before interest, tax, depreciation and amortization (adjusted EBITDA) performance, the Compensation Committee finalized the annual bonus plan goals for 2021.

Financial Goals

The 60 percent weighting of the financial goals is allocated between the total net sales goal, weighted at 35 percent, and the internal adjusted EBITDA goal, weighted at 25 percent.

Total Net Sales

The Compensation Committee established a total net sales goal for our 2021 annual bonus program rather than separate weighted net sales goals for our individual business units, which were used for our 2020 annual bonus plan. The Compensation Committee made this determination to reinforce collaboration across our business units. The performance targets for the total net sales goal are set forth below.

Internal Adjusted EBITDA

The performance targets for the internal adjusted EBITDA goal are set forth below:

Strategic Goals

The Compensation Committee established four strategic goals (with a total weighting of 40 percent) for 2021:

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The Compensation Committee chose these four strategic goals because it believed these were the best indicators of the achievement of our operating plan, and they represented the factors most critical to increasing total shareholder value in 2021.

How Did We Do?

In February 2022, based on management’s recommendations and the Compensation Committee’s review, deliberation and determination of achievement of the corporate financial and strategic goals described above, the Compensation Committee approved the achievement levels for the financial and strategic goals as shown below.

Financial Goals

Actual results in 2021 for each financial goal were as follows: