Notice of 2024 Annual Meeting of Shareholders

Important Notice Regarding the Internet Availability of Proxy Materials

for the Stockholder Meeting to Be Held on May 16, 2024

WHO CAN VOTE

Shareholders of Repligen Corporation’s Common Stock as of the close of business on March 18, 2024 (our “Record Date”). It is important that your shares be represented and voted at the 2024 Annual Meeting of Shareholders (the “Annual Meeting”). Whether or not you plan to attend the virtual Annual Meeting, please complete and return the enclosed proxy card in the envelope provided or vote by internet or telephone pursuant to instructions provided with the proxy card.

NOTICE AND ACCESS

We are mailing a Notice of Internet Availability of Proxy Materials (the “Notice”) to our shareholders instead of paper copies of our Proxy Statement. The Notice contains instructions on how to access our Proxy Materials over the internet. The Notice also contains instructions on how shareholders can receive a paper copy of our Proxy Materials, free of charge, including this Proxy Statement and proxy card.

Our Annual Report to Shareholders, containing a letter from our Chief Executive Officer and financial statements for the fiscal year ended December 31, 2023 (the “2023 Annual Report”), is also being provided together with this Proxy Statement to all stockholders entitled to vote at the Annual Meeting.

HOW TO VOTE

Our Annual Meeting will again be held in a virtual meeting format only, via the internet, with no physical in-person meeting. At our virtual Annual Meeting, shareholders will be able to attend, vote and submit questions as set forth in this section.

Voting instructions are the same for registered shareholders (shares are registered in your name with Repligen’s transfer agent, American Stock Transfer) and beneficial owners (shares are held in a stock brokerage account or by a bank or other holder of record). Here’s how to vote prior to the Annual Meeting:

		By internet at www.proxyvote.com		By phone 1-800-690-6903		By mail, complete and return your proxy card or voting instruction form

You may also vote at the Annual Meeting via www.virtualshareholdermeeting.com/RGEN2024. You will need the 16-digit control number included with these proxy materials to vote electronically, to vote by phone, and/or to attend the virtual Annual Meeting. A technical support telephone number will be posted on the Annual Meeting login page so that you can call if you encounter any difficulties accessing the Annual Meeting during the check-in or during the meeting.

Execution of a proxy card, or voting by telephone or via the internet prior to the Annual Meeting, will not in any way limit a shareholder’s right to attend the virtual Annual Meeting and vote during the meeting.

HOW TO SUBMIT QUESTIONS

If you are a shareholder of record as of our Record Date, you may ask questions during the Annual Meeting. To do so, you will need to have your 16-digit control number available. During the formal portion of the meeting, your questions must be related to proposals listed under “Voting Matters” above, and more specifically to the particular proposal being discussed at the time. To ask a question during the Annual Meeting, click the Q&A button on the virtual meeting platform and enter your question in the text box. If questions submitted are repetitive as to a particular topic, the Chairperson of the meeting may limit discussion on such topic. We will also hold a question-and-answer period following the formal portion of the meeting, as time permits, during which time we welcome questions not relating to specific proposals.

DATE OF MAILING

It is anticipated that the Notice will be first sent or given to our shareholders on or about April 1, 2024. At this time, the Notice, the Proxy Statement, proxy card, and the 2023 Annual Report are available for viewing, printing, and downloading at www.proxyvote.com.

By Order of the Board of Directors

Jason K. Garland

Chief Financial Officer

April 1, 2024

Table of Contents

PROXY STATEMENT SUMMARY

We are furnishing this Proxy Statement and the related proxy materials in connection with the solicitation by our Board of Directors (“Board”) of proxies to be voted at the 2024 Annual Meeting of Shareholders (the “Annual Meeting”) and at any adjournment or postponement thereof. We are providing these materials to the holders of record of our Common Stock as of the close of business on March 18, 2024, and are first making available or mailing the materials on or about April 1, 2024. This summary highlights information contained elsewhere in the Proxy Statement. As this summary does not contain all the information that you should consider in connection with the Annual Meeting, we recommend that you read the entire Proxy Statement carefully before voting.

References throughout the Proxy Statement to “Repligen Corporation”, “Repligen”, “we”, “us”, “our”, or the “Company” refer to Repligen Corporation and its subsidiaries, taken as a whole, unless the context otherwise indicates.

VOTING MATTERS

Please see the sections titled “General Annual Meeting Information” on page 58 and “Additional Information” on page 60 for important information about the proxy materials, including voting methods, vote requirements for adoption of each proposal, effect of abstentions and the deadlines to submit shareholder proposals and director nominations for next year’s Annual Meeting of Shareholders.

OUR DIRECTOR NOMINEES

You are being asked to vote on the election of the following nine (9) nominees to our Board. All directors are elected annually by the affirmative vote of a majority of votes cast. The chart below summarizes our director nominees’ personal information and current committee memberships. You can find detailed information about each director nominee’s background, skill sets and areas of expertise later in this Proxy Statement.

BOARD COMPOSITION

We continuously evaluate our director skill sets and expertise for alignment with Repligen’s strategic goals. Our independent directors bring extensive experience in areas that are critical to the Company’s strategy and long-term success, such as biopharmaceutical manufacturing, global and commercial operations, and finance. Below we highlight the key skills and experiences of our director nominees that are critical to Repligen’s success.

In addition to diversity of skills and experience, we believe that establishing and maintaining a Board that includes diverse demographics, such as gender, race, ethnicity, culture, nationality and sexual orientation, is important because having

varying perspectives and a breadth of experience improves the quality of dialogue, contributes to more effective decision-making on behalf of the Company and its shareholders, and enhances the overall chemistry and collaborative culture in the boardroom. Our Board includes directors who represent ethnic diversity, and three (3) of our nine (9) director nominees are women, one of whom serves as the Chairperson of our Board.

BOARD COMPOSITION

To see our Board Diversity Matrix as of April 11, 2023, please see our 2023 Definitive Proxy Statement, which we filed with the Securities and Exchange Commission on April 11, 2023.

CORPORATE GOVERNANCE HIGHLIGHTS

Repligen is committed to implementing and maintaining effective corporate governance practices that further long-term shareholder value, promote the Board’s accountability, and align the interests of our executive team with those of our shareholders. The following represent the key elements of our corporate governance programs:

SHAREHOLDER ENGAGEMENT

We actively seek and highly value the views and insights of our shareholders. We meet regularly with our shareholders through an ongoing schedule of investor discussions, in-person meetings, banking conferences, non-deal roadshows and other events. In addition to our traditional investor relations outreach efforts focused on analysts and portfolio manager communications, we engage with shareholder stewardship and proxy governance teams to discuss proxy proposals, overall governance and executive compensation programs, and ESG reporting and initiatives. These discussions often involve our Board Chairperson and/or Board committee members, our CEO, members of our executive management team as appropriate, and our Global Head of Investor Relations.

Our shareholder engagement activities have guided certain Board meeting agendas and have led to governance enhancements addressing the issues that matter most to our shareholders. We consider this ongoing engagement process important in creating long-term value, and maintaining a culture of integrity, compliance and sustainability.

Conversations with institutional investors in 2023 and into 2024 covered a wide range of topics, primarily focused on the impacts of confluent headwinds on Repligen growth and financial performance, both near- and long-term. Our discussions with investors centered on order growth, rebalancing and rightsizing activities, the impact of our key accounts commercial strategy, the importance of our new product launches in the market, our presence in new modalities end markets, and forward-year expectations for revenue growth and margin expansion.

SUSTAINABILITY – ENVIRONMENTAL, SOCIAL AND GOVERNANCE MATTERS

We believe our commitment to sustainability initiatives across all of our global facilities matters and is an important part of creating long-term business value for all stakeholders. We are deeply committed to corporate responsibility and transparency, and we continue to factor sustainability into our business decisions and integrate its core principles into our daily operations.

Together, we are advancing our ESG initiatives at an ambitious pace and taking bold steps to engage stakeholders throughout our upstream and downstream value chain.

To view or download our most recent 2022 sustainability report, “Making An Impact” and/or to access our 2022 reporting frameworks indexes document, please visit www.repligen.com/company/sustainability.

ESG Oversight

Our commitment to sustainability oversight at both the Board and management levels reflects the importance we place on ESG-driven policies and programs to support our long-term strategic plan. The Chair of our Nominating and Corporate Governance (“N&CG”) Committee oversees our ESG initiatives and practices as set forth in the N&CG Committee charter. This Chair also reviews and approves the information contained in our sustainability reports. The N&CG Committee reports to the full Board on ESG matters and the Company’s progress on sustainability programs and initiatives. For more details about our ESG Oversight hierarchy, please see the section titled “ESG Oversight” on page 23.

Compensation-Related ESG Measures

Beginning in 2022, based in part on shareholder input, the N&CG Committee determined that NEOs will annually be assigned certain ESG responsibilities, as appropriate to their roles, to support and advance defined corporate ESG goals. Their level of effectiveness in helping to achieve the corporate ESG goals is considered when determining the individual achievement component of performance-based compensation. For more information about our compensation-related ESG goals and outcomes, please see section titled “Sustainability Goals and Outcomes: 2023” on page 24.

EXECUTIVE COMPENSATION HIGHLIGHTS

Repligen’s compensation philosophy is to provide compensation that will attract and retain high-performing talent in our industry, motivate the Company’s executive officers to create long-term, enhanced shareholder value, provide a fair reward for robust effort and stimulate our executive officers’ professional and personal growth. The Company believes that the compensation of its executive officers should align the executive officers’ interests with those of the shareholders and focus executive officer behavior not only on the achievement of near-term corporate goals, but also on the achievement of long-term business objectives and strategies. For more on compensation philosophy see the section titled “Executive Compensation” on page 34.

Compensation Earned

The graphs below reflect the allocation of salary, cash incentive compensation and equity incentive compensation earned by the Company’s CEO, Chief Financial Officer (“CFO”), President and Chief Commercial Officer (“CCO”), Chief Operating

Officer, Senior Vice President, Filtration & Chromatography, and Senior Vice President, Research & Development in 2023, all six of whom were serving as executive officers as of December 31, 2023 as well as our former CFO, Jon Snodgres, who retired from the Company effective October 31, 2023, and who ceased serving as CFO effective upon the hiring of the new CFO on September 25, 2023. We have elected to provide disclosure of compensation information for all of our 2023 executive officers, whom we refer to as NEOs throughout the Proxy Statement for simplicity. Additional NEO compensation detail and notes can be found in the “Executive Compensation Tables — 2023 Summary Compensation Table” on page 41.

2023 Summary Compensation Allocations

The following table sets forth the total compensation earned by the NEOs during 2023. For more information on the total compensation see “Executive Compensation Tables — 2023 Summary Compensation Table” on page 41.

Long-term Equity Incentive Breakout for NEOs

We believe that the mix of time-based and performance-based equity awards under our long-term incentive compensation program provides balance to the program, motivates our executives to drive organizational achievement of our near- and long-term corporate goals and aligns the interests of our executive officers with those of our shareholders.

As shown in the graph below, the target split of the annual long-term equity incentive compensation awards made to our NEOs based upon dollar value is 25% performance-based restricted stock units (“PSUs”), 25% stock options subject to time-based vesting, and 50% restricted stock units subject to time-based vesting (“RSUs”). Our Compensation Committee annually reviews our long-term equity incentive program and has determined that the current composition and weightings remain appropriate in furthering our objective of recruiting and retaining top talent in our industry at this time.

PSU awards are earned only if we achieve three-year Adjusted Return on Invested Capital (“Adjusted ROIC”) and specific three-year revenue growth goals, which are set at challenging levels and weighted at 50% each. The revenue growth goals are either based on compound annual growth rate (“CAGR”) or average annual growth rate. The Compensation Committee set sequentially more aggressive three-year Adjusted ROIC and revenue growth goals for the 2021, 2022 and 2023 PSU awards. The revenue goals for the 2021 program reflect three-year average organic revenue growth for the total business. For the 2022-2024 programs, the Compensation Committee set the revenue targets for these programs based on organic growth in base business (“Base Organic Growth”), excluding revenue related to COVID-19 from the programs due to the volatility in demand related to COVID-19 and associated revenues. Base Organic Growth excludes the impact of revenue related to COVID-19, inorganic acquisition-related revenue (revenue recognized by acquired companies during the reporting period for which there is no prior year comparison), and the impact of changes in foreign exchange rates.

Long-term Equity Incentive Payout for NEOs for 2023

In 2021, we granted PSU awards subject to a three-year performance period ending December 31, 2023. As shown in the table below, these PSU awards were earned at 48% of target. This was based on 95% achievement of the organic revenue growth goal and 0% achievement of the Adjusted ROIC goal for the PSU awards, each of which was equally weighted at 50%.

The following table presents the performance goals and actual achievement for the 2021 program:

We have granted our NEOs performance-based equity awards, including PSUs, each year since 2019 and we anticipate that we will continue to include such equity awards as part of our long-term incentive compensation program going forward for the reasons noted above.

BUSINESS & FINANCIAL HIGHLIGHTS 2023

A Challenging Year for Bioprocessing

2023 proved to be an overall challenging year for our industry and Repligen, as we adjusted to a post-pandemic environment following three years of capacity expansion and hiring to meet unprecedented acceleration in demand for our products. As the pandemic reached endemic status, Repligen and the bioprocessing industry faced multiple headwinds—most significantly were elevated inventory levels at both biopharmaceutical (“Pharma”) and contract development and manufacturing organizations (“CDMO”) customer accounts, as inventory had been secured during the long-lead time supply chain environment. The de-stocking impact of this persisted through 2023. This was coupled with conservative capital spending and project delays at large Pharma accounts. In addition, a high inflationary environment resulted in significant contraction in funding for startup biotech companies, and regionally, the industry was affected by economic deterioration in China, both of which had some impact on Repligen, albeit to a lesser extent than our peers.

Positive Signs by Year End

The first half of 2023 was particularly challenging, as the funnel of opportunities across our customer base was limited. In the second half of 2023, our opportunity funnel started to improve, and by year end, we were encouraged to see positive

signs of recovery at Repligen. Orders picked up, especially in the third quarter for Pharma accounts, and in the fourth quarter for CDMO accounts. We have many reasons for optimism; most fundamentally, the underlying growth and expansion of the biologics markets we serve, and our unique positioning as a recognized technology leader in bioprocessing.

2023 Business & Financial Highlights

Business Focus: Key Account Strategy, New Modality Inroads, Innovation and Rebalancing Resources

In 2023, we focused our attention on five areas, aligned with our goals set up at the beginning of the fiscal year. We strengthened the commercial team with the addition of a key account team in North America. We intensified our efforts to build a strong opportunity funnel and expand our presence in new modalities. We prioritized research and development (“R&D”) as we continued to focus on innovation, committing similar dollars to R&D as in 2022. In addition to these three areas, we took necessary actions to rebalance the organization in response to margin pressures we faced from lower sales volume in the post-pandemic market. This was balanced with investments in key site upgrades.

Financial Highlights

Sustainability

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS, DIRECTORS AND MANAGEMENT

The following table sets forth certain information regarding beneficial ownership of shares of our Common Stock as of March 18, 2024 by: (i) each person who is known by the Company to beneficially own more than 5% of the outstanding shares of Common Stock; (ii) each director or nominee of the Company; (iii) each named executive officer of the Company; and (iv) all directors nominees and executive officers of Repligen as a group. The business address of each director and executive officer is Repligen Corporation, 41 Seyon Street, Building #1, Suite 100, Waltham, Massachusetts 02453.

PROPOSAL 1

ELECTION OF DIRECTORS

DIRECTOR NOMINEES

There are nine (9) nominees for director, all of whom are current directors of Repligen that have been nominated by the Nominating and Corporate Governance (“N&CG”) Committee and the Board of Directors (“Board”) for re-election.

If elected, each of the director nominees will hold office until the 2025 Annual Meeting of Shareholders and until his or her successor has been duly elected and qualified, or until his or her earlier death, resignation or removal.

Shares represented by all proxies received by the Board and not marked or voted to abstain from voting for any individual director or for any group of directors will be voted, unless otherwise indicated, FOR the election of the nominees named above. Proxies may not be voted for a greater number of persons than the number of nominees named. The Board knows of no reason why any nominee should be unable or unwilling to serve, but if any nominee should be unable or unwilling to serve, proxies will be voted in accordance with the judgment of the persons named as attorneys-in-fact on the proxy cards with respect to the directorship for which that nominee was unable or unwilling to serve.

Proposal 1 relates solely to the election of the nine (9) above-named directors nominated by the Company and does not include any other matters relating to the election of directors, including without limitation, the election of directors nominated by any shareholders of the Company.

The Board unanimously recommends a vote FOR each of the nominees for election as directors of the Company. If authorized proxies are submitted without specifying an affirmative or negative vote on any proposal, the shares represented by such proxies will be voted in favor of the Board’s recommendations.

OCCUPATIONS OF DIRECTORS AND EXECUTIVE OFFICERS

Repligen’s executive officers are appointed by, and serve at the discretion of, the Board. Each executive officer is a full-time employee of Repligen. The current directors, including director nominees, and executive officers of Repligen as of March 18, 2024 are as follows:

BIOGRAPHICAL INFORMATION

The following paragraphs provide information about the Company’s continuing directors and executive officers. The information presented includes information about each director’s specific experience, qualifications, attributes and skills that led the Board to the conclusion that he or she should serve as a director.

Executive Officers

		Tony J. Hunt was named President and Chief Executive Officer (“CEO”) and has served on the Board since May 2015. He currently serves as CEO after relinquishing his role as President in October 2023. He joined Repligen in May 2014 as Chief Operating Officer (“COO”), overseeing commercial and manufacturing operations. Before coming to Repligen, Mr. Hunt was President of Bioproduction at Life Technologies Corporation, a global life sciences company which was acquired by Thermo Fisher Scientific (“Thermo Fisher”) in 2014. He joined Life Technologies in 2008, serving as General Manager of Bioproduction Chromatography and Pharma Analytics before being named President of Bioproduction in 2011. From 2000 to 2008, Mr. Hunt was with Applied Biosystems as Senior Director of Pharma Programs where he launched the Pharma Analytics business that in

2008 became a part of the Bioproduction platform at Life Technologies. Mr. Hunt also serves on the board of directors of one publicly traded company, 908 Devices Inc. Mr. Hunt received a B.S. in Microbiology and an M.S. in Biotechnology from University College in Galway, Ireland, and a M.B.A. from Boston University School of Management. Mr. Hunt brings to the Board his deep understanding of the bioprocessing market.

		Jason K. Garland joined Repligen in September 2023 as the CFO, where he oversees financial operations for the Company. Mr. Garland holds responsibility for all corporate finance and audit functions, capital markets and M&A transactions, financial planning and analysis, budgeting and financial risk management of the Company as well as information technology and investor relations of the Company. Mr. Garland was previously with Integer Holdings Corporation (“Integer”), a medical device outsource manufacturer, where he served for nearly five years as Executive Vice President and CFO, and assumed executive sponsorship of the company’s business process excellence initiatives focused on standardizing and optimizing all non-manufacturing processes. Prior to his role with Integer, Mr. Garland spent three years as Vice President and CFO for the global sales and supply

divisions of Tiffany & Co., following nearly 20 years of increasing responsibility at General Electric Corporation (“GE”). His rotations and achievements at GE culminated in several leadership positions including his role as CFO for GE Industrial Solutions, then a multi-billion dollar business with over 40 manufacturing sites. Mr. Garland serves on the board of directors and is Audit Committee Chair for Acutus Medical, a publicly-traded medical device company. He holds a B.S. in Chemical Engineering from the University of New Hampshire, and is Lean Six Sigma Black Belt certified.

		James R. Bylund was named COO of the Company in January 2022 and serves as the Company’s principal operating officer. He joined Repligen in March of 2020 as Senior Vice President, Global Operations and IT, overseeing all operations and IT functions on a global basis. Between March 2019 and March 2020, Mr. Bylund also worked in real estate at Inspire Development in Austin, Texas. Prior to joining Repligen, Mr. Bylund spent ten years at Thermo Fisher in a number of roles including Vice President and General Manager of the Single Use Technologies Business Unit and Vice President of Global Operations for the Bioproduction Division. Prior to joining Thermo Fisher, Mr. Bylund also worked for Fiserv (nine years) and Eli Lilly and Company (seven years) in

a variety of leadership roles. He has significant experience in managing multiple operating sites across the globe and scaling operations to meet rapidly growing demand. Mr. Bylund is a passionate proponent of continuous improvement and has consistently demonstrated the ability to assemble and grow highly effective teams. He holds a B.S. in Accounting from Utah State University and an M.B.A. from Indiana University.

		Christine Gebski joined Repligen in May 2015 and currently serves as the Senior Vice President, Filtration and Chromatography where she oversees the general management and strategy of the Company’s upstream and downstream filtration and chromatography portfolio. Prior to joining Repligen, Ms. Gebski was head of the Chromatography Business Unit within the Bioproduction Division of Thermo Fisher. At Thermo Fisher she managed the Global Process Chromatography Applications and research and development (“R&D”) functions for ten years. Before joining Thermo Fisher, Ms. Gebski was a Process Development Scientist for 15 years in the biotechnology industry, having held positions of increasing responsibility at Genzyme, TKT/Shire and EMD Pharmaceuticals. She has significant experience in product development and commercialization,

product life cycle management, downstream process development and engineering, technology transfer and validation across a variety of biological molecule classes and diagnostic reagents. She holds a B.S. in Biology from the University of Vermont and a M.S. in Biotechnology from the University of Massachusetts at Lowell.

		Ralf Kuriyel joined Repligen in October 2016 as the Senior Vice President, R&D where he oversees the Company’s R&D efforts. Mr. Kuriyel was previously Vice President of Applications for the single-use business unit within the Life Sciences division of Pall Corporation (“Pall”), whose acquisition by Danaher Corporation was completed in August 2015. At Pall, Mr. Kuriyel served as Vice President of R&D, Field Applications and Process Development Services from November 2014 to October 2016. In addition, Mr. Kuriyel served as Vice President, Applications R&D at Pall from November 2011 to November 2014. Mr. Kuriyel received a B.S. and an M.S. in Chemical Engineering from Rensselaer Polytechnic Institute and has completed his coursework for the Tufts

University Ph.D. program in Chemical Engineering. He is an inventor of multiple patents and has co-authored over 30 scientific publications on bioprocessing, including separations technologies, membrane separations methods, protein processing and enhanced microfiltration techniques.

		Olivier Loeillot joined Repligen in October 2023 as President and CCO, where he has responsibility for driving the Company’s commercial strategy and expanding the market impact of Repligen’s business units in bioprocessing. Mr. Loeillot joined Repligen from his most recent role as CEO of Ascensus Specialties, a manufacturer of specialty chemicals for use in the life sciences and pharmaceutical markets. Mr. Loeillot previously served a combined 12 years with Cytiva (a Danaher Corporation company) and GE Healthcare Life Sciences. At Cytiva, he served as Bioprocess President from 2018 to 2022, overseeing the overall Bioprocessing portfolio from cell culture media to purification resins and including process equipment, single-use technologies

and enterprise solutions. There, he was also instrumental in building and leading the Enterprise Solutions business, managing the Bioprocess Asia business in Singapore, and directing the Genomics and Cellular Research division. Prior to Cytiva, Mr. Loeillot served a combined 12 years with Lonza, advancing to Vice President Sales, Lonza Custom Manufacturing. He also acted as Vice President Sales for Lonza AG’s custom manufacturing business and led the Microbial Biopharmaceuticals group. Mr. Loeillot earned his Master’s degree in Chemistry in 1993 from the European High Institute of Chemistry of Strasbourg, France, and later completed a M.B.A. program at CESMA Business School of EM Lyon.

Directors

		Nicolas M. Barthelemy has served as a director of Repligen since June 2014. Mr. Barthelemy brings over 30 years of industry experience to the director role. Mr. Barthelemy served as President and CEO of bioTheranostics, a molecular diagnostics company, from September 2014 until February 2017. Prior to bioTheranostics, he served as President, Global Commercial Operations at Life Technologies, which was acquired by Thermo in February 2014. Prior to Life Technologies, Mr. Barthelemy was with Biogen Inc. (“Biogen”) for eight years, most recently as Vice President, Manufacturing and General Manager for the company’s manufacturing organization at Research Triangle Park. He began his career with Merck & Co., Inc. as a Senior

Project Engineer, Vaccine Technology. Mr. Barthelemy also serves on the board of directors of three privately held companies: Biocare Medical LLC, NanoCellect Biomedical, and Slingshot Biosciences. Mr. Barthelemy previously served as a board member of Twist Bioscience, 908 Devices Inc. and Standard BioTools, Inc. (previously Fluidigm Corporation). Mr. Barthelemy received a M.S. in Chemical Engineering from the University of California, Berkeley, and an engineering degree from Ecole Supérieure de Physique et Chimie Industrielles, Paris. Mr. Barthelemy’s qualifications to sit on the Company’s Board include his extensive experience in the bioprocessing field, including large scale biologics manufacturing and commercialization of consumables used in bioprocessing.

		Karen A. Dawes, Chairperson of the Board, has served as a director of Repligen since September 2005. She is currently President of Knowledgeable Decisions, LLC, a management consulting firm. Ms. Dawes served from 1999 to 2003 as Senior Vice President and U.S. Business Group Head for Bayer Corporation’s U.S. Pharmaceuticals Group (“Bayer”). Prior to joining Bayer, she was Senior Vice President, Global Strategic Marketing, at Wyeth LLC (“Wyeth”), a pharmaceutical company (formerly known as American Home Products), where she held responsibility for worldwide strategic marketing. Ms. Dawes also served as Vice President, Commercial Operations for Genetics Institute, Inc., which was acquired by Wyeth in January 1997, designing and implementing that company's initial commercialization strategy to launch BeneFIX® and Neumega®.

Ms. Dawes began her pharmaceuticals industry career at Pfizer, Inc. where, from 1984 to 1994, she held a number of marketing positions, serving most recently as Vice President, Marketing of the Pratt Division. At Pfizer, Inc., she directed launches of Glucotrol^®/Glucotrol XL^®, Zoloft^®, and Cardura^®. Ms. Dawes also serves on the board of directors of two publicly traded companies: Barinthus Bio (formerly Vaccitech Limited) and Medicenna Therapeutics Corp, one private company, JPA Health, and one not-for-profit company, Medicines 360. Ms. Dawes received a B.A. and M.A. in English from Simmons College and a M.B.A. from Harvard University Graduate School of Business. Ms. Dawes’ qualifications to sit on the Company’s Board include her extensive strategic experience in both a managerial and consulting capacity with pharmaceutical companies as well as her considerable commercial background.

		Carrie Eglinton Manner has served as a director of Repligen since June 2020. She brings to the director role over 25 years of leadership experience across multiple disciplines. Ms. Eglinton Manner currently serves as President and CEO of OraSure Technologies, Inc. (“OraSure”), which she joined in June 2022. OraSure, together with its wholly-owned subsidiaries, DNA Genotek, Diversigen and Novosanis, is a leader in the development, manufacture and distribution of rapid diagnostic tests, sample collection and stabilization devices, and molecular service solutions designed to discover and detect critical medical conditions. Prior to OraSure, Ms. Eglinton Manner served as Senior Vice President, Advanced & General Diagnostics and Clinical Solutions at Quest Diagnostics ("Quest"), which she joined in 2017. In her role at Quest, Ms. Eglinton Manner was responsible for

value creation across the company’s $10 billion clinical portfolio, driving innovation in R&D, along with partnerships and acquisitions. She helped accelerate growth in Quest’s $2 billion Advanced Diagnostics portfolio, which included its specialty molecular and genetic offerings, along with Quest’s global and pharmaceutical services businesses. Prior to Quest, Ms. Eglinton Manner held various roles of increasing scope and responsibility over a period of 20 years at GE Healthcare. From 2009 through 2016, she served as President & CEO of four distinct GE Healthcare global businesses in the areas of diagnostic imaging, lab services and medical devices, ranging in size from approximately $150 million to $3 billion in revenue. In addition to the Repligen Board, Ms. Eglinton Manner serves as board director for the not-for-profit Thrive Networks, focused on water supply, sanitation and hygiene, economic empowerment, gender equity, healthy cities and resilient community development to serve underserved populations of Southeast Asia, as well as Sapphiros, a KKR-backed platform building the next generation of diagnostic technologies. Ms. Eglinton Manner holds a B.S. in Mechanical Engineering from the University of Notre Dame. Ms. Eglinton Manner’s qualifications to sit on the Company’s Board include her track record of delivering business expansion and profitability for rapidly growing global businesses, including her experience with integrating acquisitions and building operations excellence, with a commitment to quality and process improvements.

		Konstantin Konstantinov, Ph.D., has served as a director of Repligen since May 2022. He has also been a member of our Scientific Advisory Board since March 2016. Dr. Konstantinov is currently Chief Technology Officer at Ring Therapeutics and Operating Partner at Flagship Pioneering. Dr. Konstantinov previously served as Chief Technology Officer at Codiak BioSciences (“Codiak”), and prior to that as Executive Vice President, Manufacturing & Process Sciences. Before joining Codiak, Dr. Konstantinov was responsible for the late-stage bioprocess and technology development at Sanofi’s Boston hub, including all functions, from cell banking to fill/finish/lyophilization. Prior to Sanofi, Dr. Konstantinov worked for Bayer in Berkeley, California for 14 years, advancing to the position of Head of Process Sciences. He has published 60 peer reviewed papers and

has more than 15 patents and patent applications. During the last 23 years, Dr. Konstantinov has worked on the development and commercialization of various products, including monoclonal antibodies, blood factors and enzymes expressed in mammalian cells. Most recently, he has pioneered the development of an end-to-end integrated continuous biomanufacturing platform, which is becoming a strategic technological trend for the biomanufacturing industry worldwide. Dr. Konstantinov received his Ph.D. in Biochemical Engineering from Osaka University, Japan, which was followed by a post-doctoral assignment at DuPont and the University of Delaware.

		Martin D. Madaus, Ph.D., has served as a director of Repligen since February 2023. Dr. Madaus joined the Board with over 25 years of industry experience, including five years as Chairman, President and CEO of Millipore Corporation, where he was integral to the company’s transformation into a life science leader, and its acquisition by Merck KGaA in 2010. He is an active board leader, currently serving as a Director at Azenta Life Sciences, a public company focused on assisting life sciences organizations bring impactful breakthroughs and therapies to markets faster, and as Lead Director for Quanterix Corporation, a precision health technology public company. Dr. Madaus previously served as a board member for mass cytometry player Standard BioTools, Inc. (previously Fluidigm Corporation). He also serves on the boards of three private companies: Unchained

Labs, Emulate Inc. and Syntis Bio. Dr. Madaus is currently a senior operating executive at The Carlyle Group (since 2019), a multinational private equity and asset management services company. He previously served as Chairman and CEO at Ortho-Clinical Diagnostics from 2014 to 2019. His tenure with biopharmaceutical and diagnostic industry leader Roche Holding AG from 1996 to 2004 included his position from 2000 to 2004 as President and CEO, N.A. of Roche Diagnostics Corp. Dr. Madaus began his career as a veterinarian, before joining global pharmaceutical and diagnostic company Boehringer Mannheim Corporation (“Boehringer”). While at Boehringer, he held sales, marketing and product management roles from 1989 to 1996, until his move into general management coincided with the company’s acquisition by Roche in 1996. He holds a D.V.M. from the University of Munich in Germany and a Ph.D. from the University of Veterinary Medicine of Hanover in Germany. Dr. Madaus’ qualifications to sit on the Company’s Board include his extensive bioprocessing and biopharmaceutical industry experience, especially in the areas of strategy, mergers and acquisitions, and commercial operations.

		Rohin Mhatre, Ph.D., was appointed to the Board in March 2020. Dr. Mhatre brings 30 years of relevant experience to the director role, including his current position since October 2023 as Executive Vice President and Chief Technical Officer at FogPharma. Prior to that he served as Senior Vice President, Product and Technology Development of Biogen from 2017 to 2023. Dr. Mhatre has also held numerous other roles of increasing responsibility within Biogen, which he joined in 1996, including six years as Vice President of Biopharmaceutical Development, where he led a team responsible for cell line, cell culture, purification and device development. Earlier in Dr. Mhatre’s career at Biogen, he focused on building out analytical

development and technical services. Prior to Biogen, Dr. Mhatre led the purification and applications group at Applied BioSystems (formerly Perspective Biosystems). Dr. Mhatre holds a Ph.D. in Chemistry from Northeastern University. Dr. Mhatre’s qualifications to sit on the Board include his extensive technical expertise, his leadership abilities and his deep understanding of the dependencies between biological drug development and efficient manufacturing workflows.

		Glenn P. Muir has served as a director of Repligen since October 2015. Mr. Muir brings over 30 years of experience to the director role, including 26 years with Hologic, Inc. (“Hologic”), a large multi-national medical device and diagnostics company where he most recently served as CFO and Executive Vice President. Mr. Muir retired in May 2014 from Hologic, where he helped steer the company’s evolution from a venture-backed single product company to a publicly-traded diversified organization with over 5,000 employees and $2.5 billion in revenue. He joined Hologic in 1988 and served as CFO since 1992 and Executive Vice President since 2000. Prior to Hologic, Mr. Muir was with Metallon Engineered Materials Co., a private company where, from 1986 to 1988 he held the role of Vice President, Finance. Previously, from 1981 to 1984, he was a Senior

Auditor with Arthur Andersen & Co. Mr. Muir also serves on the board of directors of two publicly-traded companies: medical technology company, Neuronetics, Inc., and life science company, G1 Therapeutics, Inc. Previously, Mr. Muir served on the board of directors of ReWalk Robotics Ltd. from July 2014 to December 2017. Mr. Muir is a Certified Public Accountant (inactive since 2022) with a B.A. from the University of Massachusetts, Amherst. He also earned a M.S. from Bentley University and a M.B.A. from Harvard University. Mr. Muir’s qualifications to sit on Repligen’s Board include his extensive experience with integrating strategic acquisitions and leading the financial operations for a global manufacturing and commercial organization.

		Margaret A. Pax has served as a director of Repligen since March 2024. Ms. Pax brings over 25 years of experience leading the development and execution of growth strategies for global companies. This includes eight years with Thermo Fisher, where, from 2016 to 2020, she served as Vice President, Strategy and Innovation for the clinical supply chain business. In this role, she led strategic planning, developed customer-facing innovation programs, and drove the business case for the company’s multi-billion acquisition of Patheon, a leading biopharmaceutical contract manufacturer. Ms. Pax’s background also includes her position as Senior Director, Corporate Development & Strategy at Thermo Fisher from 2013 to 2016, where she led

post-merger commercial integration for the company’s acquisition of Life Technologies. Earlier in her career with Thermo Fisher, she was the Senior Director, Portable Analytical Instrumentation from 2012 to 2013. From 1989 to 2000, Ms. Pax was with Phillips Healthcare (“Phillips”), a leading medical device company, where she held senior leadership roles in Business Development, Marketing and Product Management. Between her Phillips and Thermo Fisher roles, Ms. Pax held several entrepreneurial leadership positions, including as Vice President, Business and Clinical Development for five years (2006 to 2011) with Microchips Biomedical, an MIT startup company that was acquired by Daré Bioscience. Ms. Pax is currently an independent board director at Alimera Sciences, a Nasdaq-listed pharmaceutical company, where she has served as a director since 2023, and Jellagen, a privately-held UK company. She also sits on the board of the U.S. subsidiary of BioPorto A/S, a Danish-based kidney biomarker company. Ms. Pax advises a range of healthcare and life sciences companies on business strategy, commercial growth, and partnerships. Ms. Pax holds a B.A. from the College of Holy Cross, and an M.B.A. from Harvard Business School, where she currently serves as a board member of the Harvard Business School Healthcare Alumni Association.

CERTAIN RELATIONSHIPS AND RELATED PERSONS TRANSACTIONS

No family relationship exists among the officers and directors of Repligen. The Audit Committee conducts an appropriate review of all related party transactions for potential conflict of interest situations on an ongoing basis, and the approval of the Audit Committee is required for all such transactions. The term “related party transactions” shall refer to transactions required to be disclosed by the Company pursuant to Item 404 of Regulation S-K promulgated by the Securities and Exchange Commission (“SEC”).

DELINQUENT SECTION 16(a) REPORTS

Under U.S. securities laws, directors, certain officers and persons holding more than 10% of our Common Stock must report their initial ownership of our Common Stock and any changes in their ownership to the SEC. The SEC has designated specific due dates for these reports and we must identify in this Proxy Statement those persons who did not file these reports when due. Based solely on our review of copies of the reports filed with the SEC and the written representations of our directors and executive officers, we believe that all reporting requirements for fiscal year 2023 were complied with by each person who at any time during the 2023 fiscal year was a director or an executive officer or held more than 10% of our Common Stock, except for the following: Due to an administrative error, a Form 4 filing misreported the number of shares beneficially owned by Carrie Eglinton Manner, a current member of the Board. The required Form 4 to correct this amount was filed on December 15, 2023.

CORPORATE GOVERNANCE AND BOARD MATTERS

BOARD INFORMATION

Director Independence

The Board of Directors (“Board”) has determined that each of the directors who has served during the fiscal year ended December 31, 2023 and each of the nominees for director at the 2024 Annual Meeting of Shareholders (the “Annual Meeting”), with the exception of Mr. Hunt, has no material relationship with the Company and is independent within the meaning of the director independence standards of The Nasdaq Stock Market LLC (“Nasdaq”). Furthermore, the Board has determined that each member of the Audit Committee, the Compensation Committee and the Nominating and Corporate Governance (“N&CG”) Committee of the Board is independent within the meaning of Nasdaq’s director independence standards and that each member of the Audit Committee meets the heightened director independence standards of the Securities and Exchange Commission (“SEC”) for audit committee members.

Board Leadership Structure

The Board is led by its Chairperson, Karen Dawes, who is an independent director. The Board believes that separating the roles of the Chief Executive Officer (“CEO”) and Chairperson of the Board is the most appropriate structure for the Company at this time. Having an independent Chairperson ensures that the CEO is accountable for managing the Company in the best interests of the shareholders while, at the same time, acknowledging that managing the Board is a separate and time-intensive responsibility. Additionally, this structure ensures a greater role for the non-management directors in the oversight of the Company and active participation of the independent directors in setting agendas and establishing priorities and procedures for the work of the Board. The Board also believes that having an independent Chairperson can serve to curb conflicts of interests, promote oversight of risk and manage the relationship between the Board and the CEO.

Executive Sessions

The Board holds executive sessions of the independent directors at each regularly scheduled Board meeting and/or as deemed necessary by the Chairperson. Executive sessions do not include any employee directors of the Company, and the Chairperson of the Board is responsible for chairing the executive sessions.

Director Nomination Policies

Director Qualifications

The N&CG Committee is responsible for selecting and recommending nominees for election as directors to the Board. The full Board participates in an annual Board effectiveness assessment, which includes evaluating the appropriate qualities, skills and characteristics of current Board members and identifying skills and qualifications desired for director nominees. These assessments include consideration of the following minimum qualifications that the N&CG Committee believes must be met by all directors:

The N&CG Committee also considers numerous other qualifications, skills and characteristics when evaluating director nominees, such as:

These factors and others are considered useful by the Board and are reviewed in the context of an assessment of the perceived needs of the Board at a particular point in time.

The N&CG Committee considers candidates for Board membership, including those suggested by shareholders, applying the same criteria for all candidates. If the N&CG Committee identifies a need to replace a current member of the Board, to fill a vacancy on the Board, or to expand the size of the Board, it considers candidates from a variety of sources including third-party search firms that assist in identifying, evaluating and conducting due diligence on potential director candidates. For all potential candidates, our N&CG Committee will consider all factors it deems relevant, including those enumerated above.

Board Diversity

The N&CG Committee is committed to having a diverse Board and considers a variety of candidate attributes, including whether a candidate, if elected, assists in achieving a mix of directors who represent a diversity of backgrounds and experience. A Board that includes diversity, including diversity in gender, race, ethnicity, culture, nationality, sexual orientation, age, perspectives, personal and professional background, knowledge and experience, is important because we believe having varying perspectives and a breadth of experience improves the quality of deliberations, contributes to more effective decision-making on behalf of the Company and its shareholders and enhances the overall chemistry and collaborative culture in the boardroom. Accordingly, the N&CG Committee is committed to actively seeking out Board candidates who are highly qualified women, minorities, and individuals with other diverse backgrounds, skills and experience.

In 2023, as part of our continued board refreshment efforts, we added Dr. Madaus to our Board, who brings a necessary and specific knowledge set, specifically in bioprocessing and biopharmaceutical operations. The N&CG Committee was cognizant that this addition reduced our gender diversity. As part of the N&CG Committee’s commitment to achieving and maintaining a diverse Board, the N&CG Committee continuously looks for opportunities to attain a Board composition comprised of diverse directors and to continue to maintain or improve overall board ethnic and racial diversity. To that end, in March 2024, the N&CG identified and evaluated a qualified candidate in Margaret A. Pax, who joined the Board on March 18, 2024. With her appointment to the Board, 33% of our Board is once again gender diverse.

Process for Identifying and Evaluating Director Nominees

The Board is responsible for selecting and nominating nominees for election as directors, but delegates the selection and nomination process to the N&CG committee, with the expectation that other members of the Board or members of management will take part in the process as appropriate.

Generally, the N&CG Committee identifies candidates for director nominees in consultation with Board members and management, through the use of search firms or other advisers, through the recommendations submitted by shareholders or through such other methods as the N&CG Committee deems to be helpful in identifying candidates. Consistent with historical practices and our ongoing efforts in diversity and inclusion, we target a diverse slate of candidates. Once candidates have been identified, the N&CG Committee confirms that the candidates meet all of the minimum qualifications for director nominees established by the N&CG Committee. The N&CG Committee may gather information about the candidates through interviews, questionnaires, background checks, or any other means that the N&CG Committee deems to be helpful in the evaluation process. The N&CG Committee meets as a group to discuss and evaluate the qualities and skills of each candidate, both on an individual basis and taking into account the overall composition and needs of the Board. Based on the results of the evaluation process, the N&CG Committee recommends candidates to be interviewed by other Board directors and ultimately recommends final candidates for the Board’s approval as director nominees for election to the Board. The N&CG Committee also recommends candidates for the Board’s appointment to the committees of the Board.

Procedures for Recommendation of Nominees by Shareholders

The N&CG Committee will consider director candidates who are recommended by the shareholders of the Company. Shareholders who meet the applicable eligibility requirements under the proxy access provision of our By-laws and who wish to include nominees for our Board in the Company’s Proxy Statement for the 2025 Annual Meeting of Shareholders, or shareholders who wish to make a proposal at the 2025 Annual Meeting of Shareholders (other than a proposal made pursuant to Rule 14a-8 issued under the Securities Exchange Act of 1934, as amended (“Exchange Act”) or pursuant to the proxy access provision of our By-laws), must in each case deliver any such recommendation not later than the close of business on the 60th day, nor earlier than the close of business on the 90th day, prior to the first anniversary of the preceding year’s Annual Meeting of Shareholders. Shareholders, in submitting recommendations to the N&CG Committee for director candidates, shall follow the following procedures:

Such recommendation for nomination should be in writing and include the following:

Nominations must be sent to the attention of the Corporate Secretary of the Company by one of the two methods listed below:

Repligen Corporation

Attn: Corporate Secretary

41 Seyon Street

Building #1, Suite 100

Waltham, MA 02453

Attn: Corporate Secretary

The Corporate Secretary of the Company will promptly forward any such nominations to the N&CG Committee. Once the N&CG Committee receives the nomination of a candidate, the candidate will be evaluated and a recommendation with respect to such candidate will be delivered to the Board. Nominations not made in accordance with the foregoing policy shall be disregarded by the N&CG Committee and votes cast for such nominees shall not be counted.

In addition to satisfying the above requirements, to comply with the SEC’s universal proxy rules, shareholders who intend to solicit proxies in support of director nominees other than the Company’s nominees must provide notice that sets forth the information required by Rule 14a-19 under the Exchange Act no later than March 17, 2025.

The Company recognizes the importance of a shareholder’s ability to nominate directors to the Company’s Board. As part of the Company’s commitment to providing a director nomination process that is fair and equitable to all nominating shareholders, the Company’s Corporate Governance Guidelines provide that the Board will not, without shareholder consent, adopt any amendments to our By-laws that would require a nominating shareholder to: (i) deliver director nominations more than 90 days prior to the first anniversary of the prior year’s Annual Meeting of Shareholders; (ii) disclose to the Company such shareholder’s plans to nominate candidates to the board of directors of other public companies, or disclose prior proposals or director nominations that such shareholder privately submitted to other public companies; or (iii) disclose information to the Company about a nominating shareholder’s limited partners or business associates.

Shareholder Communication Policies

The Board provides to every shareholder the ability to communicate with the Board, as a whole, and with individual directors on the Board through an established process for shareholder communication (as that term is defined by the rules of the SEC) as follows:

For communications directed to the Board as a whole, shareholders may send such communication to the attention of the Chairperson of the Board via one of the two methods listed below:

Repligen Corporation

Attn: Chairperson of the Board of Directors

41 Seyon Street

Building #1, Suite 100

Waltham, MA 02453

Attn: Chairperson of the Board of Directors

For shareholder communications directed to an individual director in his or her capacity as a member of the Board, shareholders may send such communications to the attention of the individual director via one of the two methods listed below:

Repligen Corporation

Attn: [Name of Individual Director]

41 Seyon Street

Building #1, Suite 100

Waltham, MA 02453

Attn: [Name of Individual Director]

The Company will forward any such shareholder communication to the Chairperson of the Board, as a representative of the Board, and/or to the director to whom the communication is addressed on a periodic basis. The Company will forward such communication by certified U.S. Mail to an address specified by each director of the Board for such purposes or by secure electronic transmission.

Director Attendance Policy

The Board’s policy is that all directors and director nominees attend the Company’s Annual Meeting in person, via teleconference, or via other virtual means. All members who were on the Board as of May 18, 2023 attended the 2023 Annual Meeting of Shareholders.

Stock Ownership Guidelines and Insider Trading Policy

The Board has adopted share ownership guidelines relating to ownership of the Company’s securities by the Company’s named executive officers (“NEOs”) and non-employee directors. Subject to the terms of the policy, (i) the CEO is required to acquire over a five-year period and hold shares of Common Stock of the Company equal to five times his or her base salary as of a specified measuring date, (ii) each of the Company’s NEOs other than the CEO is required to acquire over a five-year period and hold shares of Common Stock of the Company equal to one times his or her base salary as of a specified measuring date, and (iii) each of the Company’s non-employee directors is required to acquire over a five-year period and hold shares of Common Stock of the Company equal to four times the Company’s annual cash retainer paid to each such non-employee director. Restricted stock and restricted stock units subject to time-based vesting (whether or not vested as of the measurement date) are included in the number of shares owned, but unexercised stock options (regardless of whether they are vested or unvested) and performance-based restricted stock units are not included in the total number of shares owned by the NEOs or directors for purposes of the share ownership policy. All directors and NEOs currently comply with their respective share ownership requirements or are on track to meet them within the five-year period.

Under the Company’s insider trading policy, employees, including executive officers and non-employee directors, are not permitted to engage in the following transactions with respect to the Company’s stock: selling any of the Company’s securities that are not owned by such insider at the time of sale and holding the Company’s stock in an account that is, or is linked to, a margin account. In addition, the following transactions are not permitted without pre-approval of the Company’s Audit Committee: buying or selling puts, calls or other derivatives of the Company’s securities or any derivative securities that provide the economic equivalent of ownership of any of the Company’s securities; engaging in any hedging transaction with respect to the Company’s securities; or pledging Company securities as collateral for a loan. Gifts (transfer of the Company’s stock without consideration) are subject to the same restrictions as all other trades and are prohibited during a period when the insider is not permitted to trade.

Code of Business Conduct & Ethics

Repligen has adopted a Code of Business Ethics & Conduct as its “code of ethics” as defined by regulations promulgated under the Securities Act of 1933, as amended, and the Exchange Act (and in accordance with the Nasdaq requirements for a “code of conduct”), which applies to all of the Company’s directors, officers and employees, including its principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. A current copy of the Code of Business Conduct & Ethics is available at the “Investors” — “Corporate Governance” — “Policies and Charters” section of the Company’s website at www.repligen.com. A copy of the Code of Business Conduct & Ethics may also be obtained free of charge from the Company upon a request directed to Repligen Corporation, Attention: Investor Relations, 41 Seyon Street, Building #1, Suite 100, Waltham, MA 02453. The Company will promptly disclose any substantive changes in or waivers, along with reasons for the waivers, of the Code of Business Conduct and Ethics granted to its executive officers, including its principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, and its directors by posting such information on its website at www.repligen.com under “Investors” — “Corporate Governance.”

The Board’s Role in Risk Oversight

The Company’s management is responsible for assessing and managing risk and the Board oversees and reviews the Company’s risk management process. This oversight by the Board is primarily accomplished through its committees and through management’s reporting processes, including having the Board receive regular reports from members of senior management on areas of material risk to the Company, including operational, financial, legal and regulatory, strategic, and governance risks. In addition, at the beginning of each Board meeting, the CEO provides a status update on the Company and addresses any areas of risk in an executive session. A full risk management assessment is performed and presented to the Board periodically.

The committees of the Board execute their oversight responsibility for risk management as follows:

We will continue to uphold our strong corporate governance, shareholder rights and executive compensation programs. Our Board also oversees our executive and Board succession planning strategies.

SUSTAINABILITY - ENVIRONMENTAL, SOCIAL AND GOVERNANCE MATTERS

We believe our commitment to sustainability initiatives across all of our global facilities matters and is an important part of creating long-term business value for all stakeholders. We are deeply committed to corporate responsibility and transparency, and we continue to factor sustainability into our business decisions and integrate its core principles into our daily operations.

Together, we are advancing our ESG initiatives at an ambitious pace and taking bold steps to engage stakeholders throughout our upstream and downstream value chain.

To view or download our most recent 2022 sustainability report, “Making An Impact” and/or to access our 2022 reporting frameworks indexes document, please visit www.repligen.com/company/sustainability.

ESG Oversight

Our commitment to sustainability oversight at both the Board and management levels reflects the importance we place on ESG-driven policies and programs to support our long-term strategic plan. Below is our sustainability governance hierarchy:

Compensation-Related ESG Measures

Beginning in 2022, and based in part on shareholder input, the N&CG Committee determined that NEOs will annually be assigned certain ESG responsibilities, as appropriate to their roles, to support and advance defined corporate ESG goals. Their level of effectiveness in helping to achieve the corporate ESG goals is considered when determining the individual achievement component of performance-based compensation.

Sustainability Goals and Outcomes: 2023

Below are our sustainability-related goals and outcomes disclosed in our 2023 Proxy Statement. These goals and outcomes are related to the sustainability reporting period ended December 31, 2022 unless otherwise noted.

The data included above is collected in the current year, for previous year goals. Therefore, the achievement of such goals is on a look-back basis (prior year for some of the goals and prior year plus the first half of the current year for others).

Compensation-Related Sustainability Goals: 2024

Sustainability Report Published in 2023

Our initial report published in 2021 helped to elevate awareness in the company and prompted higher levels of internal action. In 2022, with the full support of our Board, we established a dedicated Sustainability team that promotes and manages our increasingly ambitious set of ESG initiatives.

During 2023, we published our 2022 Sustainability Report, which can be found on the Company’s website. This report, “Making An Impact”, highlights our progress since 2020, and reflects our belief that corporate responsibility is essential to sustaining business and economic growth in a manner that can also deliver positive environmental and social impact.

In the 2022 Sustainability Report (published in 2023), we disclosed more about our ESG targets and where we have made meaningful progress since our last report. Examples include: our transition to 100% renewable electricity at additional key sites; the diversion of waste streams from landfills to recyclers; steps forward on a single-use recycling pilot program; outcomes from our most recent employee engagement survey and advances in our initiatives for a diverse and inclusive workplace.

Our Sustainability Report Frameworks

In “Making An Impact”, we continued to disclose against internationally recognized reporting frameworks, including the United Nations Global Compact (“UNGC”) Communication on Progress, Global Reporting Initiative Universal Standard 2021 and Sustainability Accounting Standards Board Standards frameworks. We also added to our formalized reporting commitment with our first Carbon Disclosure Project responses on Climate and Water, using guidance from the GHG Protocol and the Task Force on Climate-related Financial Disclosures. As a signatory of the UNGC, Repligen aligns with its Ten Principles on human rights, labor, the environment and anti-corruption. We maintained focus on seven Sustainable Development Goals as the most relevant to our business.

To view or download our most recent 2022 sustainability report, “Making An Impact,” and/or to access our 2022 reporting frameworks indexes document, please visit www.repligen.com/company/sustainability.

BOARD MEETINGS AND COMMITTEES

The Board of Directors (“Board”) met six (6) times during the fiscal year ended December 31, 2023. During the fiscal year ended December 31, 2023, each director attended 100% of each of: (i) the total number of meetings of the Board (during the period for which he or she was a director); and (ii) the total number of meetings held by all committees of the Board on which such director served (during the periods that he or she served). The Board has a standing Audit Committee, Compensation Committee, and Nominating and Corporate Governance (“N&CG”) Committee. Each of these standing committees has a charter that has been approved by the Board. Each standing committee reviews the appropriateness of its charter periodically, as conditions dictate, but at least annually.

AUDIT COMMITTEE

The Audit Committee was established in accordance with Section 3(a)(58)(A) of the Securities Exchange Act of 1934, as amended (“Exchange Act”), and currently consists of Mr. Muir, Dr. Madaus and Ms. Eglinton Manner. Dr. Madaus replaced Ms. Dawes as a member of the Audit Committee in March 2023. The Audit Committee is responsible for overseeing the accounting and financial reporting processes of the Company and the audits of the financial statements of the Company and exercising the responsibilities and duties set forth below, including but not limited to:

The Audit Committee met four (4) times during the fiscal year ended December 31, 2023. Mr. Muir currently serves as Chairperson of the Audit Committee. The Board has determined that Mr. Muir qualifies as an “audit committee financial expert” under the rules of the SEC. The Board has determined that each member of the Audit Committee is independent within the meaning of the Nasdaq Stock Market LLC’s (“Nasdaq’s”) director independence standards and the SEC’s heightened director independence standards for audit committee members as determined under the Exchange Act.

The Audit Committee operates under a written charter adopted by the Board, a current copy of which is available on the Company’s website at www.repligen.com under “Investors” — “Corporate Governance” — “Policies and Charters.”

COMPENSATION COMMITTEE

The Compensation Committee, of which Mr. Barthelemy, Mr. Muir and Dr. Mhatre are currently members, is responsible (among other duties and responsibilities) for:

The Compensation Committee met four (4) times during the fiscal year ended December 31, 2023. Mr. Barthelemy serves as the Chairperson of the Compensation Committee. The Board has determined that each member of the Compensation Committee is independent within the meaning of the SEC and Nasdaq’s director independence standards.

The Compensation Committee operates under a written charter adopted by the Board, which is available on the Company’s website at www.repligen.com under “Investors” — “Corporate Governance” — “Policies and Charters.”

NOMINATING AND CORPORATE GOVERNANCE COMMITTEE

The N&CG Committee of the Board consists of Ms. Dawes, Mr. Barthelemy, Dr. Konstantinov, and Dr. Madaus. Each of Dr. Konstantinov and Dr. Madaus joined the N&CG Committee in March 2023. The N&CG Committee met two (2) times during the fiscal year ended December 31, 2023. The N&CG Committee is responsible for:

The N&CG Committee may also consider director nominees recommended by the Company’s shareholders as described above.

Ms. Dawes serves as the Chairperson of the N&CG Committee. The Board has determined that each member of the N&CG Committee is independent within the meaning of the SEC’s and Nasdaq’s director independence standards.

The N&CG Committee operates under a written charter adopted by the Board, which is available on the Company’s website at www.repligen.com under “Investors” — “Corporate Governance” — “Policies and Charters.”

Other Committees of the Board

Our Board may, as needed or advisable from time to time, form temporary, ad hoc or other standing committees and delegate the authority to oversee, identify, evaluate or negotiate a specific issue, opportunity and function, and to, as appropriate, make recommendations to the full Board. For example, our Board has established a Transaction Committee to oversee, advise on and assist our management and the full Board in considering or pursuing acquisitions, partnering and other business development opportunities.

PROPOSAL 2

RATIFICATION OF THE SELECTION OF OUR INDEPENDENT REGISTERED

PUBLIC ACCOUNTING FIRM

The Audit Committee of the Board of Directors (“Board”) has appointed Ernst & Young LLP (“EY”), an independent registered public accounting firm, to serve as independent auditors for the fiscal year ended December 31, 2023. EY has served as the Company’s independent registered public accounting firm since 2002. In accordance with standing policy, EY periodically changes the personnel who work on the audits of the Company.

AUDIT AND NON-AUDIT FEES

The following sets forth the aggregate fees billed by EY to the Company and incurred by the Company during the fiscal years ended December 31, 2023 and 2022:

Audit Fees

Fees for audit services were approximately $2,077,764 and $2,230,600 for the fiscal years ended December 31, 2023 and 2022, respectively. These amounts included fees associated with the annual audit of the consolidated financial statements, reviews of the Company’s Quarterly Reports on Form 10-Q and fees associated with the statutory filings and filings with the Securities and Exchange Commission (“SEC”).

Audit-Related Fees

There were no audit-related fees for the fiscal years ended December 31, 2023 and 2022. These fees would include fees for assurance and related services rendered by EY that are reasonably related to the performance of the audit or the review of our consolidated financial statements and that are not included as audit fees. These services would also include due-diligence in connection with acquisitions any other contractually-agreed-upon audits, accounting consultations or attestation procedures.

Tax Fees

Fees billed for tax services were approximately $719,884 and $151,000 for the fiscal year ended December 31, 2023 and 2022, respectively. These amounts included fees associated with transfer pricing studies, the performance of a research and development credit study, tax due diligence, consulting and related services.

All Other Fees

EY billed $5,000 in additional fees in 2023 and 2022 relating to a subscription to EY’s online accounting research service.

The Audit Committee of the Board has implemented procedures under the Company’s Audit Committee Pre-Approval Policy for Audit and Non-Audit Services (the “Pre-Approval Policy”), to ensure that all audit and permitted non-audit services provided to the Company are approved by the Audit Committee. Specifically, the Audit Committee pre-approves the use of EY for specific audit and non-audit services, within approved monetary limits. If a proposed service has not been pre-approved pursuant to the Pre-Approval Policy, then it must be specifically pre-approved by the Audit Committee before EY may provide the services. Any pre-approved services exceeding the limits pre-approved by the Audit Committee must again be pre-approved by the Audit Committee. All of the audit-related, tax and other services provided by EY to the Company for the fiscal year ended December 31, 2023 were pre- approved by the Audit Committee. All non-audit services provided in the fiscal year ended December 31, 2023 were reviewed with the Audit Committee, which concluded that the provisions of such services by EY was compatible with the maintenance of that firm’s independence in the conduct of its auditing functions.

In connection with the audit for the fiscal year ended December 31, 2023, there were no disagreements with EY on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedure, which, if not resolved to the satisfaction of EY, would have caused them to refer to such disagreement in connection with their report.

A member of EY is expected to be present at the 2024 Annual Meeting of Shareholders with the opportunity to make a statement if so desired and will be available to respond to appropriate questions.

Accordingly, the Board believes ratification of the appointment of EY as the Company’s independent registered public accounting firm for the current year is in the best interests of the Company and its shareholders and recommends a vote FOR the ratification of EY as the Company’s independent registered public accounting firm.

AUDIT COMMITTEE REPORT

This report is furnished by the Company’s Audit Committee with respect to the Company’s financial statements for fiscal year 2023. The Company’s management is responsible for the preparation and presentation of complete and accurate financial statements. The independent registered public accounting firm EY is responsible for performing an independent audit of the Company’s financial statements in accordance with the standards of the Public Company Accounting Oversight Board (United States) (“PCAOB”) and for issuing a report on its audit. The Audit Committee oversees and monitors the Company’s management and its independent registered public accounting firm throughout the financial reporting process.

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 filing of the Company under the Securities Act of 1933, as amended or under 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 currently consists of Mr. Muir, Chairperson, Dr. Madaus and Ms. Eglinton Manner. Dr. Madaus replaced Ms. Dawes as a member of the Audit Committee on March 2, 2023. The Audit Committee has the responsibility and authority described in the Repligen Audit Committee Charter, which has been approved by the Board. The Board has determined that the members of the Audit Committee meet the independence requirements set forth in Rule 10A-3(b)(1) under the Exchange Act and the applicable rules of the National Association of Securities Dealers, Inc., and that Mr. Muir qualifies as an “audit committee financial expert” under the rules of the SEC. The Audit Committee oversees the accounting and financial reporting processes of the Company and the audits of the financial statements of the Company. Management has the primary responsibility for the financial statements and the reporting process, including the systems of internal controls.

In fulfilling its oversight responsibilities, the Audit Committee reviewed and discussed with management of the Company and EY the audited financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023 (“Form 10-K”), including a discussion of the quality, not just the acceptability, of the accounting principles, the reasonableness of significant judgments and the clarity of disclosures in the financial statements. The Audit Committee also reviewed the Company’s quarterly financial statements for the first three fiscal quarters during the fiscal year ended December 31, 2023 and discussed them with both the management of the Company and EY prior to including such interim financial statements in the Company’s Quarterly Reports on Form 10-Q. In connection with the Company’s Form 10-K for the fiscal year ended December 31, 2023 and the Form 10-Q for each of its first, second and third fiscal quarters of the fiscal year ended December 31, 2023, the Audit Committee discussed the results of the Company’s certification process relating to the statements in the Company’s Form 10-Qs, as well as financial statements under Sections 302 and 906 of the Sarbanes-Oxley Act. The Audit Committee also discussed with EY the matters required to be discussed by the PCAOB’s Auditing Standard No. 1301, Communication with Audit Committees, and the SEC. In addition, the Audit Committee has received from EY the written disclosures and the letter from EY as required by applicable requirements of the PCAOB regarding EY’s communications with the Audit Committee concerning independence and has discussed with EY their independence.

The Audit Committee also reviewed management’s report on its assessment of the effectiveness of the Company’s internal control over financial reporting and EY’s report on the effectiveness of the Company’s internal control over financial reporting.

The Audit Committee discussed with EY the overall scope and plans for their audit. The Audit Committee met with EY to discuss the results of their examinations, their evaluations of the Company’s internal controls, including internal control over financial reporting, and the overall quality of the Company’s financial reporting.

The Audit Committee has also evaluated the performance of EY, including, among other things, the amount of fees paid to EY for audit and non-audit services. Based on its evaluation, the Audit Committee has selected EY to serve as the Company’s auditors for the fiscal year ending December 31, 2024. The shareholders of the Company are being asked to ratify the selection of EY as the Company’s independent public accounting firm in Proposal 2 of this Proxy Statement.

The Audit Committee met four (4) times during the fiscal year ended December 31, 2023. In reliance on the reviews and discussions referred to above, the Audit Committee recommended to the Board that the Company’s audited financial statements and management’s assessment of the effectiveness of the Company’s internal controls over financial reporting be included in Form 10-K, and the Board approved such inclusion.

Respectfully submitted by the Audit Committee,

Glenn P. Muir, Chairperson

Martin D. Madaus

Carrie Eglinton Manner

PROPOSAL 3

ADVISORY VOTE ON EXECUTIVE COMPENSATION

The Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 enables our shareholders to vote to approve, on an advisory basis, the compensation of our named executive officers (“NEOs”) as disclosed in this Proxy Statement in accordance with the Securities and Exchange Commission’s (“SEC’s”) rules.

As described in the section titled “Compensation Discussion and Analysis” which begins on page 31 and in the accompanying tables and narrative disclosure, our executive compensation programs are designed to motivate our executive officers to enhance shareholder value, to provide a fair reward for this effort and to stimulate our executive officers’ professional and personal growth. The Company seeks to provide near-term and long-term financial incentives that align the executive officers’ interests with those of the shareholders and focus executive officer behavior on the achievement of near-term corporate goals, as well as long-term business objectives and strategies. We believe that this alignment between executive compensation and shareholder interests has driven corporate performance over time.

Our shareholders voted on May 18, 2023, to have advisory votes every year to approve the compensation paid to the Company’s NEOs, and we have adopted that approach. The Board of Directors (“Board”) and Compensation Committee make executive compensation decisions every year, and our directors look to the annual advisory vote for information to be taken into account when they make decisions with respect to our compensation philosophy, policies and practices. Accordingly, we are asking our shareholders to vote FOR the following non-binding, advisory resolution on the approval of the compensation of the Company’s NEOs as disclosed in this Proxy Statement:

“RESOLVED, that the shareholders of the Company approve, on an advisory basis, the compensation of the Company’s NEOs, as disclosed in this Proxy Statement, including the Compensation Discussion and Analysis, compensation tables and narrative discussion.”

We urge you to read the “Compensation Discussion and Analysis” section of this Proxy Statement and the accompanying tables and narrative disclosure for additional details on the Company’s executive compensation, including our governance, framework, components, and the compensation decisions for the NEOs for the fiscal year ended December 31, 2023.

As an advisory vote, the results of this vote will not be binding on the Board or the Company. However, the Board and the Compensation Committee value the opinions of our shareholders and will consider the outcome of the vote when making future decisions on the compensation of our NEOs and the Company’s executive compensation principles, policies and procedures.

The Board unanimously recommends that shareholders vote FOR approval, on an advisory basis, of the compensation of the Company’s NEOs, as disclosed in this Proxy Statement, including the “Compensation Discussion and Analysis”, compensation tables and narrative discussion.

COMPENSATION COMMITTEE REPORT

The Compensation Committee of the Board, which is comprised solely of independent directors as defined under the applicable rules of the Nasdaq Stock Market LLC and non-employee directors as defined under Rule 16b-3 under the Securities Exchange Act of 1934, as amended, is responsible for developing executive compensation policies, advising the Board with respect to such policies, and administering the Company’s cash and equity incentive plans. The Compensation Committee sets performance goals and objectives for the Chief Executive Officer (“CEO”) and the other executive officers, evaluates their performance with respect to those goals and sets their compensation based upon the evaluation of their performance. In evaluating executive officer pay, the Compensation Committee may retain the services of a compensation consultant and consider recommendations from the CEO with respect to goals and compensation of the other executive officers. The Compensation Committee assesses the information it receives in accordance with its business judgment. The Compensation Committee also periodically reviews non-employee director compensation. All decisions with respect to executive compensation are approved by the Compensation Committee and all decisions with respect to director compensation are recommended by the Compensation Committee to the full Board for approval.

The Compensation Committee of the Company has reviewed and discussed the “Compensation Discussion and Analysis” required by Item 402(b) of Regulation S-K promulgated by the SEC with management and, based on such review and discussions, the Compensation Committee recommended to the Board that the “Compensation Discussion and Analysis” be included in this Proxy Statement.

Respectfully submitted by the Compensation Committee:

Nicolas M. Barthelemy, Chairperson

Rohin Mhatre, Ph.D.

Glenn P. Muir

COMPENSATION DISCUSSION AND ANALYSIS

Our Compensation Discussion and Analysis describes our executive compensation philosophy and program. We have elected to provide disclosure in this section for all of our 2023 executive officers, whom we refer to as named executive officers (“NEOs”). The executive compensation tables that follow provide information relating primarily to 2023 compensation decisions for the following NEOs:

2023 LEADERSHIP CHANGES

Mr. Loeillot joined the Company as our President and Chief Commercial Officer (“CCO”), effective October 2, 2023 and, in connection with Mr. Loeillot’s appointment, Mr. Hunt relinquished his role of President. Mr. Garland joined the Company as Chief Financial Officer (“CFO”), effective September 25, 2023, replacing Mr. Snodgres, who retired as CFO effective September 25, 2023 but continued in a full-time advisory role with the Company until October 31, 2023. In connection with their appointments, Mr. Loeillot and Mr. Garland entered into employment agreements with the Company, which are described in the section titled “Employment Arrangements” on page 46.

BUSINESS & FINANCIAL HIGHLIGHTS 2023

Information on business and financial highlights of the Company for 2023 can be found in the Proxy Statement Summary in the section titled “Business & Financial Highlights 2023” on page 8.

COMPENSATION PHILOSOPHY

In accordance with the Company’s compensation philosophy, the Company provides compensation that the Compensation Committee believes will attract and retain high-performing talent in our industry, motivate the Company’s executive officers to create long-term, enhanced shareholder value, and provide a fair reward for executive effort and stimulate professional and personal growth.

It is the responsibility of the Compensation Committee of the Board of Directors (“Board”) to administer the Company’s compensation programs to ensure that they are competitive with other bioprocessing, healthcare supply and biotechnology companies, and to include incentives that are designed to appropriately drive the Company’s continued development to create shareholder value. The Compensation Committee reviews and approves all components of the Company’s executive officer compensation, including base salaries, annual cash incentive compensation, and equity incentive compensation.

COMPENSATION OBJECTIVES

The Company believes that the compensation of its executive officers should align the executive officers’ interests with those of the shareholders and focus executive officer behavior not only on the achievement of near-term corporate goals, but also on the achievement of long-term business objectives and strategies.

To achieve these objectives, the Company’s compensation program for its executive officers:

The following features of our compensation programs are designed to protect and promote the interests of our shareholders while aligning executive compensation with performance.