Use these links to rapidly review the document
Table of Contents

Table of Contents

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.                        )

Table of Contents

NOTICE

and

PROXY STATEMENT

for

ANNUAL MEETING OF SHAREHOLDERS

MAY 15, 201812, 2020

10 Finderne Avenue, Building 10700 US Highway 202/206
Bridgewater, New Jersey 08807

Table of Contents

Insmed Incorporated
10 Finderne Avenue, Building 10700 US Highway 202/206
Bridgewater, New Jersey 08807
(908) 977-9900

April 5, 2018March 31, 2020

To Our Shareholders:

              We cordially invite you to attend the 20182020 Annual Meeting of Shareholders of Insmed Incorporated (Insmed) to, which, in light of the COVID-19 pandemic and related public health concerns, will be held virtually via the Internet at the Bridgewater Marriott, 700 Commons Way, Bridgewater, New Jersey 08807,www.virtualshareholdermeeting.com/INSM2020 on May 15, 2018,12, 2020, at 9:00 a.m. localEastern time (the Annual Meeting). A formal notice of the Annual Meeting accompanies this letter. At the Annual Meeting, the following items will be submitted to a shareholder vote:

1.

election of twothree Class IIIII directors, Clarissa Desjardins, Ph.D., David R. BrennanW.J. McGirr, and Melvin Sharoky, M.D.,Elizabeth McKee Anderson, to serve until the 20212023 Annual Meeting of Shareholders;



2.

an advisory vote on the 20172019 compensation of our named executive officers;



3.

ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for the year ending December 31, 2018;2020;



4.

approval of an amendment to the Insmed Incorporated 2018 Employee Stock Purchase2019 Incentive Plan; and



5.

transaction of such other business as may properly come before the Annual Meeting or any adjournment or postponement thereof.

              Your vote is important, and the company encourages you to vote. Please read the notice and proxy materials carefully, and vote promptly in advance of the meeting by telephone, electronically through the Internet, or by returning a completed proxy card by mail. You may also vote in person atattend the Annual Meeting.Meeting and vote and submit questions during the Annual Meeting via the Internet at www.virtualshareholdermeeting.com/INSM2020. Whether or not you plan to attend the Annual Meeting in person and regardless of the number of shares of Insmed common stock you own, please vote by proxy prior to the Annual Meeting.

              You may inspect a list of shareholders of record as of the record date at Insmed's headquarters during regular business hours starting on April 7, 2018 through the date of the Annual Meeting, and the list of shareholders will be available at the Annual Meeting for inspection.

This Proxy Statement is first being mailed to shareholders on or about April 5, 2018.March 31, 2020.

Table of Contents

INSMED INCORPORATED
10 Finderne Avenue, Building 10700 US Highway 202/206
Bridgewater, New Jersey 08807
(908) 977-9900

NOTICE OF ANNUAL MEETING OF SHAREHOLDERS
TO BE HELD ON MAY 15, 201812, 2020

              NOTICE IS HEREBY GIVEN that the 20182020 Annual Meeting of Shareholders of Insmed Incorporated (Insmed) will be held virtually via the Internet at the Bridgewater Marriott, 700 Commons Way, Bridgewater, New Jersey 08807,www.virtualshareholdermeeting.com/INSM2020, on May 15, 2018,12, 2020, at 9:00 a.m. localEastern time (the Annual Meeting), and at any adjournment or postponement thereof, for the following purposes:

1.

To elect twothree Class IIIII directors, Clarissa Desjardins, Ph.D., David R. BrennanW.J. McGirr, and Melvin Sharoky, M.D.,Elizabeth McKee Anderson, to serve until the 20212023 Annual Meeting of Shareholders;



2.

To conduct an advisory vote on the 20172019 compensation of our named executive officers;



3.

To ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm for the year ending December 31, 2018;2020;



4.

To approve an amendment to the Insmed Incorporated 2018 Employee Stock Purchase2019 Incentive Plan; and



5.

To transact such other business as may properly come before the Annual Meeting or any adjournment or postponement thereof.

              Due to the COVID-19 pandemic and public health concerns, the Annual Meeting will be a completely virtual meeting of shareholders. Holders of record of shares of Insmed common stock at the close of business on March 23, 201818, 2020 will be entitled to vote at the Annual Meeting.

              You are requested to vote promptly in advance of the Annual Meeting by telephone, electronically through the Internet, or by returning a completed proxy card by mail regardless of whether you expect to attend the Annual Meeting. If you are present atattend the Annual Meeting, you may vote in person even if you already have sent in your proxy. If you are a beneficial owner, you may not vote your shares in person at the Annual Meeting unless you request and obtain a valid proxy from your broker or other agent.

April 5, 2018March 31, 2020

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE INSMED INCORPORATED ANNUAL MEETING OF SHAREHOLDERS TO BE HELD ON MAY 15, 2018:12, 2020: The Proxy Statement and Annual Report on Form 10-K for the year ended December 31, 20172019 are available atwww.proxyvote.com.

Table of Contents

PROXY STATEMENT
for
ANNUAL MEETING OF SHAREHOLDERS
of
INSMED INCORPORATED
To be held May 15, 201812, 2020

Table of Contents

In this Proxy Statement, we use the words "Insmed Incorporated" to refer to Insmed Incorporated, a Virginia corporation, and we use the words "Company," "Insmed," "we," "us" and "our" to refer to Insmed Incorporated and its consolidated subsidiaries. Insmed, CONVERT and CONVERTARIKAYCE are trademarks of Insmed Incorporated. This Proxy Statement also contains trademarks of third parties. Each trademark of another company appearing in this Proxy Statement is the property of its owner.

Table of Contents

PROXY STATEMENT
for
ANNUAL MEETING OF SHAREHOLDERS
of
INSMED INCORPORATED
To be held May 15, 201812, 2020

GENERAL INFORMATION ABOUT THE ANNUAL MEETING AND VOTING

Distribution of Proxy Solicitation and Other Required Annual Meeting Materials

              The Board of Directors (the Board) of Insmed Incorporated is soliciting your proxy for the Annual Meeting of Shareholders to be held at the Bridgewater Marriott, 700 Commons Way, Bridgewater, New Jersey 08807, on May 15, 2018,12, 2020, at 9:00 a.m. localEastern time (the Annual Meeting), and any adjournment or postponement thereof. Due to the COVID-19 pandemic and related public health concerns, the Annual Meeting will be held virtually via the Internet at www.virtualshareholdermeeting.com/INSM2020. We intend to make the Proxy Statement and related proxy materials available to our shareholders on or about April 5, 2018.March 31, 2020.

Information about the Annual Meeting and Voting at or Prior to the Annual Meeting

              Why Did I Receive a One-page Notice in the Mail Regarding the Internet Availability of Proxy Materials this Year Instead of a Full Set of Proxy Materials?

              Pursuant to rules adopted by the Securities and Exchange Commission (SEC),SEC, we have elected to mail to many of our shareholders a Notice of Internet Availability of the Proxy Materials (the Notice) instead of a paper copy of the proxy materials. All shareholders receiving the Notice will have the ability to access the proxy materials over the Internet and receive a paper copy of the proxy materials by mail on request. Instructions on how to access the proxy materials over the Internet or to request a paper copy may be found in the Notice. In addition, the Notice contains instructions on how you may request proxy materials in printed form by mail or electronically on an ongoing basis. This process has allowed us to expedite our shareholders' receipt of proxy materials, lower the costs of distribution and reduce the environmental impact of our Annual Meeting.

              Who May Vote Shares in Connection with the Annual Meeting?

              Shareholders of record at the close of business on March 23, 201818, 2020 (the Record Date), will be entitled to notice of and to vote at the Annual Meeting. As of the Record Date, we had 76,623,13689,859,549 outstanding shares of our common stock, $0.01 par value per share (the Common Stock). Each share of our Common Stock entitles the holder to one vote with respect to all matters submitted to shareholders at the Annual Meeting. Beneficial owners of shares of our Common Stock may direct the record holder of the shares on how to vote the shares held on their behalf.

              Who may participate in the Annual Meeting?

              This year's Annual Meeting will take place virtually through the Internet, in light of the COVID-19 pandemic and related public health concerns. We have designed the format of this year's Annual Meeting to ensure that our shareholders who attend the Annual Meeting will be afforded the same rights and opportunities to participate as they would at an in-person meeting. You are entitled to attend and participate in the Annual Meeting only if you were a shareholder of record as of the close of business on the Record Date, or if you hold a valid proxy for the meeting, as described below. To be admitted to the Annual Meeting at www.virtualshareholdermeeting.com/INSM2020, you must enter the

Table of Contents

16-digit control number found on your proxy card or other proxy materials. If you do not have a control number, please contact the brokerage firm, bank, dealer, or other similar organization that holds your account as soon as possible so that you can be provided with a control number.

What is a Shareholder of Record and How Can I Vote if I am a Shareholder of Record?

              If, as of the close of business on the Record Date, shares of our Common Stock were registered directly in your name with our transfer agent, then you are a shareholder of record. As a shareholder of record, you may vote by proxy or in personadvance or at the Annual Meeting.

              If you are a shareholder of record, you may vote or submit a proxy as follows:

1.

By Internet—


Before the Annual Meeting—You may authorize the voting of your shares by following the "Vote by Internet" instructions set forth on the Notice or proxy card through 11:59 p.m. Eastern Time on

Table of Contents

Monday, May 14, 2018.11, 2020. You must specify how you want your shares voted or your vote will not be completed and you will receive an error message.

During the Annual Meeting—You may vote online during the Annual Meeting. You may cast your vote electronically during the Annual Meeting using the 16-digit control number found on your proxy card or other proxy materials and following the instructions at www.virtualshareholdermeeting.com/INSM2020.

2.

By Telephone—Dial 1-800-690-6903 using any touch-tone phone to transmit your voting instructions through 11:59 p.m. Eastern Time on Monday, May 14, 2018.11, 2020. Have your proxy card in hand when you call and follow the voting instructions given to you over the phone.



3.

ByBy Mail—Complete and sign the proxy card and mail it in accordance with the instructions on the proxy card. Completed proxy cards must be received by 9:00 a.m.11:59 p.m. Eastern Time on Tuesday,Monday, May 15, 2018.



4.

In Person at the Meeting—If you attend the Annual Meeting, you may deliver a completed and signed proxy card in person or you may vote by completing a ballot, which we will provide to you at the Annual Meeting.11, 2020.

              In all cases, your shares will be voted according to your instructions.

              What is a Beneficial Owner of Shares and How Can I Vote if I am a Beneficial Owner?

              If, on the Record Date, your shares of our Common Stock were not held in your name with our transfer agent, but ratherinstead were 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 these proxy materials have been forwarded to you by that organization. The organization holding your account is considered to be the shareholder of record of shares of our Common Stock for purposes of voting at the Annual Meeting and is required to vote those shares in accordance with your instructions. If you do not give instructions to the organization holding your account, then the organization will have discretion to vote the shares with respect to "routine" matters but will not be permitted to vote the shares with respect to "non-routine" matters. See "What Matters at the Annual Meeting are 'Routine' and 'Non-Routine'?" below. As a beneficial owner, you are invited to attend the Annual Meeting.Meeting via the Internet at www.virtualshareholdermeeting.com/INSM2020. If you are a beneficial owner and not the shareholder of record, you may not vote your shares in person at the Annual Meeting unless you request and obtain a valid proxy from your broker or other agent.

Table of Contents

What if I Need Technical Assistance During the Annual Meeting?

              We encourage you to access the Annual Meeting before it begins. Online check-in will start shortly before the meeting on May 12, 2020. If you encounter any difficulties accessing the virtual meeting during the check-in or meeting time, please call the technical support number that will be posted on the virtual Annual Meeting log-in page.

              What is the Quorum Requirement?

              A quorum of shareholders is necessary to hold the Annual Meeting. Shares of our Common Stock representing a majority of the votes entitled to be cast on a matter at the Annual Meeting (or 38,311,56944,929,775 shares as of the Record Date) will constitute a quorum for the transaction of business with respect to such matter, unless otherwise provided by law or in our Articles of Incorporation, as amended (Articles of Incorporation). Votes withheld, abstentions and broker non-votes count as present for establishing a quorum.

              What Matters at the Annual Meeting are "Routine" and "Non-Routine"?

              Proposal 1, the election of Class IIIII directors, Proposal 2, the advisory vote on the 2019 compensation of our named executive officers, and Proposal 4, the approval of an amendment to the Insmed Incorporated 2018 Employee Stock Purchase2019 Incentive Plan (the 2018 Employee Stock Purchase2019 Incentive Plan), are non-routine matters. Proposal 3, the ratification of the appointment of anour independent registered public accounting firm, is a routine matter. If you are a beneficial owner of shares of our Common Stock and do not instruct your broker or other agent how to vote, your shares with respect to thewill not be voted on "non-routine" matters and your shares will be "broker non-votes" with respect to that proposal, which means your shares will not be voted.

Table of Contentsthose proposals.

              What are the Voting Requirements to Approve Each Proposal to be Submitted to Shareholders?

              The vote required to elect directors and approve each of the matters scheduled for a vote at the Annual Meeting is set forth below:

              Proposal 1, the election of Class IIIII directors, requires the affirmative vote of the holders of a plurality of the votes cast. This means that the three nominees who receive the highest number of affirmative votes cast will be elected irrespective of how small the number of affirmative votes is in comparison to the total number of shares voted. Our Board, however, has adopted a director resignation policy, under which a director nominee in an uncontested election must submit his or her resignation for consideration by our Nominations and Governance Committee and our Board if the number of votes withheld with respect to such director's election exceeds the number of votes "for" such director's election. See "Corporate Governance—Corporate Governance Matters—Director Resignation Policy" for additional information.

Table of Contents

              Proposal 2, the advisory vote on the 20172019 compensation of our named executive officers, is not binding on, nor does it overrule, any decisions of the Company, the Board or the Compensation Committee. We value the input of our shareholders, and in the event that Proposal 2 is not approved by a majority of votes cast, the Board and the Compensation Committee will consider our shareholders' concerns and evaluate what actions, if any, may be appropriate to address those concerns.

              Proposal 3, the ratification of the appointment of Ernst & Young as our independent registered public accounting firm for the year ending December 31, 2018,2020, does not require shareholder ratification under Virginia law, our Articles of Incorporation, or our Amended and Restated Bylaws (Bylaws). However, the Board is submitting the appointment of Ernst & Young to the shareholders for ratification as a matter of good corporate governance. In the event that Proposal 3 is not approved by a majority of votes cast, the Audit Committee will consider the vote in future independent auditor selection decisions.

              Proposal 4, the approval of an amendment to the 2018 Employee Stock Purchase2019 Incentive Plan, requires the affirmative vote of a majority of the votes cast in person or by proxy, at the Annual Meeting.

              What Is the Effect of Votes Withheld, Abstentions and Broker Non-Votes On Each of the Proposals?

              Votes that are withheld or any abstentions from voting will not be counted in determining the number of votes cast with respect to any of the proposals. As explained above, because Proposals 1, 2 and 4 are considered "non-routine," if a beneficial owner does not instruct the broker or other agent how to vote the shares, broker non-votes will result. Broker non-votes will not be counted in determining the number of votes cast with respect to these proposals. Because Proposal 3 is considered "routine," the broker or other agent will have discretion to vote any shares with respect to which a

Table of Contents

beneficial owner does not provide instructions, and no broker non-votes will occur with respect to this proposal.

              What if I Submit a Proxy But Do Not Specify How I Would Like to Vote?

              If we receive a signed and dated proxy card or receive your instructions by Internet or by telephone and your instructions do not specify how your shares are to be voted, your shares will be voted as follows:

•

FOR the election of each of the twothree Class IIIII nominees for director,director;



•

FOR the approval of the 20172019 compensation of our named executive officers,officers;



•

FOR the ratification of the appointment of Ernst & Young as our independent registered public accounting firm for the year ending December 31, 2018,2020; and



•

FOR the approval of an amendment to the 2018 Employee Stock Purchase2019 Incentive Plan.

              Unsigned proxy cards will not be voted.

              What If Other Matters Not on the Proxy Card Are Brought Before the Annual Meeting for Action by the Shareholders?

              As of the date of this Proxy Statement, the Board does not intend to present any matters other than those described herein at the Annual Meeting and is not aware of any matters to be presented by other parties. If other matters are properly brought before the Annual Meeting, or any adjournment or

Table of Contents

postponement thereof, for action by the shareholders, proxies will be voted in accordance with the recommendation of the Board or, in the absence of such a recommendation, in accordance with the judgment of the proxy holders.

              How Can I Revoke a Proxy Once I Have Voted?

              Anyone giving a proxy may revoke it at any time before it is votedexercised by voting in person at the Annual Meeting or by delivering, including by phone or Internet, a later dated proxy or written notice of revocation to our Corporate Secretary. Attendance at the Annual Meeting will not itself revoke a proxy. A proxy, if executed, properly delivered and not revoked, will be voted at the Annual Meeting.

              What is the Expected Cost of Soliciting Proxies and Who Will Pay for this Cost?

              We will pay the cost of soliciting proxies. In addition to the use of mail and email,e-mail, proxies may be solicited in person or by telephone by our employees, with no additional remuneration. We have engaged The Proxy Advisory Group, LLC to assist in the solicitation of proxies and provide related advice and informational support, for a service fee, plus customary disbursements, which are not expected to exceed $15,000 in total.

Principal Executive Offices of Insmed

              The address of our principal executive offices is 10 Finderne Avenue, Building 10,700 US Highway 202/206, Bridgewater, New Jersey 08807.

Table of Contents

PROPOSAL NO. 1


ELECTION OF CLASS IIIII DIRECTORS

              Our organizational documentsBylaws currently provide that our Board will consist of not less than six or more than ten10 directors. Our Board has adopted resolutions providing for up to nine directors. The directors are divided into three classes—Class I, Class II, and Class III. Each class of directors serves for three years on a staggered term basis, and the term of our Class IIIII directors will expire at the Annual Meeting. Accordingly, the Board has nominated Clarissa Desjardins, Ph.D., David R. BrennanW.J. McGirr and Melvin Sharoky, M.D.Elizabeth McKee Anderson for election as Class IIIII directors. Each of the nominees was recommended for election by the Nominations and Governance Committee, and such recommendation was approved by the Board. If re-elected,elected, the term of office for these nominees will expire at our 20212023 Annual Meeting of Shareholders. If one of these bona fide nominees set forth in this Proxy Statement is unable to serve or for good cause will not serve, proxy holders may vote for another nominee proposed by the Board or, as an alternative, the Board may reduce the number of directors to be elected at the Annual Meeting. The information below describes the primary experience, qualifications and skills of Dr. Desjardins, Mr. McGirr and Ms. Anderson.

Table of Contents

Table of Contents

Vote Required for Election of Director Nominees

              Our Class II directors will be elected by a plurality of the votes properly cast at the Annual Meeting. Votes withheld and broker non-votes will not have any effect on the outcome of this vote.

Recommendation

THE BOARD RECOMMENDS THAT YOU VOTE "FOR" EACH OF THE CLASS II DIRECTOR NOMINEES.

Table of Contents

Our Remaining Board Members

              The information below describes the primary experience, qualifications and skills of each of our Class III directors, David R. Brennan, Melvin Sharoky, M.D., and Dr. Sharoky.Leo Lee, and Class I directors, Alfred F. Altomari, Steinar J. Engelsen, M.D., and William H. Lewis. The term of the Class III directors will expire at the 2021 Annual Meeting of Shareholders, and the term of the Class I directors will expire at the 2022 Annual Meeting of Shareholders.

Incumbent Directors Whose Term Expires at the 2021 Annual Meeting of Shareholders (Class III Directors)

Table of Contents

Table of Contents THE BOARD RECOMMENDS THAT YOU VOTE "FOR" EACH OF THE CLASS III DIRECTOR NOMINEES.

Vote Required for Election of Director Nominees

              Our Class III directors will be elected by a plurality of the votes properly cast, in person or by proxy, at the Annual Meeting. Votes withheld and broker non-votes will not have any effect on the outcome of this vote.

Our Remaining Board Members

              The information below describes the primary experience, qualifications and skills of each of our Class I directors, Alfred F. Altomari, Steinar J. Engelsen, M.D., and William H. Lewis, and Class II directors, Donald Hayden, Jr., David W.J. McGirr, and Myrtle Potter. The term of the Class I directors will expire at the 2019 Annual Meeting of Shareholders, and the term of the Class II directors will expire at the 2020 Annual Meeting of Shareholders.

Table of Contents

Incumbent Directors Whose Term Expires at the 20192022 Annual Meeting of Shareholders (Class I Directors)

Table of Contents

Table of Contents

Incumbent Directors Whose Term Expires at the 2020 Annual Meeting of Shareholders (Class II Directors)

Table of Contents

Vote Required for Election of Director Nominees

              Our Class II directors will be elected by a plurality of the votes properly cast at the Annual Meeting. Votes withheld and broker non-votes will not have any effect on the outcome of this vote.

Recommendation

THE BOARD RECOMMENDS THAT YOU VOTE "FOR" EACH OF THE CLASS II DIRECTOR NOMINEES.

Table of Contents

Our Remaining Board Members

              The information below describes the primary experience, qualifications and skills of each of our Class III directors, David R. Brennan, Melvin Sharoky, M.D., and Leo Lee, and Class I directors, Alfred F. Altomari, Steinar J. Engelsen, M.D., and William H. Lewis. The term of the Class III directors will expire at the 2021 Annual Meeting of Shareholders, and the term of the Class I directors will expire at the 2022 Annual Meeting of Shareholders.

Incumbent Directors Whose Term Expires at the 2021 Annual Meeting of Shareholders (Class III Directors)

Table of Contents

Table of Contents

Table of Contents

Incumbent Directors Whose Term Expires at the 2022 Annual Meeting of Shareholders (Class I Directors)

Table of Contents

Table of Contents

Vote Required for Election of Director Nominees

              Our Class II directors will be elected by a plurality of the votes properly cast at the Annual Meeting. Votes withheld and broker non-votes will not have any effect on the outcome of this vote.

Recommendation

THE BOARD RECOMMENDS THAT YOU VOTE "FOR" EACH OF THE CLASS II DIRECTOR NOMINEES.

Table of Contents

Our Remaining Board Members

              The information below describes the primary experience, qualifications and skills of each of our Class III directors, David R. Brennan, Melvin Sharoky, M.D., and Leo Lee, and Class I directors, Alfred F. Altomari, Steinar J. Engelsen, M.D., and William H. Lewis. The term of the Class III directors will expire at the 2021 Annual Meeting of Shareholders, and the term of the Class I directors will expire at the 2022 Annual Meeting of Shareholders.

Incumbent Directors Whose Term Expires at the 2021 Annual Meeting of Shareholders (Class III Directors)

Table of Contents

Table of Contents

Table of Contents

Incumbent Directors Whose Term Expires at the 2022 Annual Meeting of Shareholders (Class I Directors)

Table of Contents

Table of Contents

Executive Officers

              The following table sets forth our current executive officers, their ages, the positions currently held by each such person as of the date of this Proxy Statement and the period holding such positions.

              William H. Lewis.    Mr. Lewis's biographical information is summarized above under "Incumbent Directors Whose Term Expires at the 20192022 Annual Meeting of Shareholders (Class I Directors)."

              Paolo Tombesi.Sara Bonstein.    Mr. TombesiMs. Bonstein joined Insmed as Chief Financial Officer in June 2017. Mr. TombesiJanuary 2020. Ms. Bonstein brings over 20more than 15 years of experienceoperational and financial leadership in the biotechnology and pharmaceutical sector.life sciences

Table of Contents

industry. Prior to joining the Company, Mr. TombesiMs. Bonstein was Vice President and Chief Financial and Administrative Officer of Novartis Pharmaceuticals Corporation, a position he held since November 2014. Mr. Tombesi was Managing Director and Chief Financial Officer & Chief Operating Officer of Novartis JapanOncoSec Medical Incorporated, a position she held since May 2018. From February 2014 to April 2018, Ms. Bonstein served as the Chief Financial Officer, Secretary, Treasurer and Executive Vice President at Advaxis, Inc. Prior to Advaxis, Ms. Bonstein was a Six Sigma Champion & Black Belt at Eli Lilly and Company (Lilly) from April 2009January 2012 to October 2014 and heldFebruary 2014. From August 2004 to December 2011, Ms. Bonstein served in various finance roles at Novartis from September 2006ImClone Systems (acquired by Lilly in 2008), including Director of Development Finance. From May 2001 to March 2009. Mr. Tombesi held several finance director positionsAugust 2004, Ms. Bonstein was a financial analyst at Bristol-Myers Squibb from August 1996 to September 2006. From January 1988 to July 1996, Mr. Tombesi held various positions in consumer goods at Unilever NV and Johnson & Johnson. Mr. TombesiJohnson in both the Ortho McNeil Pharmaceuticals and Ortho Biotech divisions. Ms. Bonstein holds a B.Ed. inMasters of Business and Managerial EconomicsAdministration from Sapienza Università di RomaRider University and a B.A.Bachelor of Science in AccountingFinance from Duca degli Abruzzi Roma.The College of New Jersey.

              Roger Adsett.    Mr. Adsett joined Insmed as Chief Commercial Officer in September 2016.2016 and was promoted to Chief Operating Officer in November 2019. Mr. Adsett has over 20 years of experience in the global biotechnology and pharmaceutical industry. From January 2015 to September 2016, Mr. Adsett was Senior Vice President, Head of Gastrointestinal and Internal Medicine Business Unit at Shire Plc (Nasdaq: SHPG) (Shire), a global specialty biopharmaceutical company. From August 2008 to January 2015, Mr. Adsett was Senior Vice President, Gastrointestinal Business Unit Leader at Shire. From October 2005 to August 2008, Mr. Adsett was General Manager, Oral IBD Products of the Gastroenterology Business Unit of Shire. From November 1994 to October 2005, Mr. Adsett held various marketing and commercial roles at AstraZeneca plc, (NYSE: AZN), a multinational pharmaceutical and biopharmaceutical company. Mr. Adsett was a senior analyst at Accenture PLC, (NYSE: ACN), a global professional services company, from September 1991 to November 1994. Mr. Adsett holds a Masters of Business Administration from The Wharton School at the University of Pennsylvania and a Bachelor of Arts in English and Economics from Bucknell University.

              Paul Streck.Martina Flammer, M.D.    Dr. StreckFlammer joined Insmed as Chief Medical Officer in June 2017.December 2019. Dr. StreckFlammer has over 2517 years of clinical development, managementexperience in both medical and leadership expertise. He most recently served ascommercial roles in the global biotechnology and pharmaceutical industry. From February 2018 to October 2019, Dr. Flammer was Head of Corporate Division Customer Value, Senior Vice President Global Medical Specialty Franchise, Immuno-inflammation at GlaxoSmithKline, a position he held since November 2015, where he was responsible for portfolio strategy, including drug launch, life cycle management, post-registration clinical strategy and health economics.Boehringer Ingelheim International. From November 20072012 to November 2015,2018, Dr. StreckFlammer held various positions at Shire Pharmaceuticals. Dr. Streck served as GroupBoehringer Ingelheim, including Vice President, Clinical Development/TA Lead (Hematology, Gastrointestinal, Internal Medicine) at Shire Pharmaceuticals from November 2013 to November 2015. Prior to that, Dr. Streck

Table of Contents

served as Global Head ofDevelopment and Medical Affairs Internal(2016 - 2018), Vice President of Medicine, (November 2012 to December 2013), Product General Manager, Emerging Business Unit (November 2011 to November 2012)Regulatory Affairs & Pharmacovigilance (2014 - 2016), and Senior Global Medical Director, Global Clinical Development (November 2007& Medical Affairs Virology (2012 - 2014). Prior to December 2012). From February 2006her time at Boehringer Ingelheim, Dr. Flammer served in various roles at Pfizer, Inc. from 2000 to October 2007,2011. Dr. Streck was Director of Marketing at AMGEN USA Inc. Dr. StreckFlammer holds aan M.B.A. from the DukeNew York University FuquaStern School of Business aand an M.D. from JeffersonUniversity of Vienna Medical College, a D.M.D. from the Temple University School of Dentistry and a B.A. in chemistry from Rutgers University.School.

              Christine Pellizzari.    Ms. Pellizzari joined Insmed as General Counsel and Corporate Secretary in July 2013 and was promoted to Chief Legal Officer in January 2018. Ms. Pellizzari has over 20 years of experience in the global biotechnology and pharmaceutical industry, including senior-level leadership roles. From August 2007 to December 2011, Ms. Pellizzari served as Executive Vice President, General Counsel and Secretary for Aegerion and served as a legal consultant for Aegerion from January 2012 to June 2012. From 1998 to 2007, Ms. Pellizzari served as Senior Vice President, General Counsel and Secretary of Dendrite International, Inc., a publicly traded company that provided the global pharmaceutical industry with sales effectiveness, promotional and compliance solutions until it was acquired by Cegedim S.A. (Euronext: CGM) in 2007. Prior to her tenure at Dendrite, Ms. Pellizzari practiced law at the firm of Wilentz, Goldman & Spitzer where she specialized in health care transactions and related regulatory matters. Before joining Wilentz, Ms. Pellizzari served as a law clerk to the Honorable Reginald Stanton, Assignment Judge for the Superior Court of New Jersey. Ms. Pellizzari received her Bachelor of Arts degree, cum laude, from the University of Massachusetts, Amherst and her Juris Doctor degree from the University of Colorado, Boulder.

Table of Contents

              S. Nicole Schaeffer.    Ms. Schaeffer joined Insmed as Senior Vice President, Human Resources and Corporate Services in January 2013 and was promoted to Chief People Strategy Officer in January 2018. From October through December 2012, Ms. Schaeffer was a consultant to Insmed. Ms. Schaeffer has more than 25 years of experience in human resources, organizational development, corporate operations, and building life science organizations. From March 2005 to June 2012, Ms. Schaeffer served as Senior Vice President, Administration and Human Resources, for Amicus Therapeutics where she was responsible for the human resources, facilities, and information technology functions. Prior to Amicus, she served as Senior Director, Human Resources, for three portfolio companies of Flagship Ventures (now Flagship Pioneering), a venture capital firm, and in that capacity she managed human resources for three life sciences companies. Ms. Schaeffer also held HR leadership positions with Oak Industries, from 1997 to 2000, and EMC Corporation, from 1994 to 1996. Ms. Schaeffer received her Bachelor of Arts degree from the University of Rochester and her Masters of Business Administration degree from Boston University.

              John Soriano.    Mr. Soriano joined Insmed as Chief Compliance Officer in January 2018, bringing over 30 years of experience in legal and compliance leadership roles. From August 2010 to November 2017, Mr. Soriano served as Senior Vice President and Chief Compliance Officer at Celgene Corporation where he oversaw the Global Compliance Program. From November 2000 to February 2010, Mr. Soriano served as Vice President-Compliance and Deputy General Counsel at Ingersoll-Rand Company. Prior to that, Mr. Soriano worked as a litigation attorney at Becton Dickinson and Co. (December 1998—November 2000), Johnson & Johnson (February 1998—December 1998), and Simpson Thacher & Bartlett (September 1987—February 1998). Mr. Soriano received his Bachelor of Arts degree from Princeton University's Woodrow Wilson School of Public and International Affairs and his Juris Doctor degree from Harvard Law School.

Table of Contents

CORPORATE GOVERNANCE

Corporate Governance Matters

              Corporate Governance Materials and Practices.    Our written corporate governance materials, including our Bylaws, Corporate Governance Guidelines, Code of Business Conduct and Ethics, Audit Committee Charter, Compensation Committee Charter, Nominations and Governance Committee Charter, Science and Technology Committee Charter, and Director Resignation Policy are posted on our website at www.insmed.com under the heading "Investor Relations—"Investors—Corporate Governance." None of the information in or that can be accessed through our website is incorporated by reference in this Proxy Statement. Our corporate governance practices include the following:

•

The Board currently has ana lead independent director, which our Corporate Governance Guidelines require in the event that the positions of Chairman and CEO are combined, and all of our non-employee directors and board committee members are independent.



•

The Board has adopted a director resignation policy in uncontested director elections.



•

The Board oversees succession planning for executive officers, including the CEO.



•

Directors have access to all levels of management and are provided with opportunities to meet with members of management on a regular basis.



•

Directors may retain their own independent advisors, at our expense.



•

The Board and each committee thereof conduct self-evaluations at least once per year to assess their performance and ways in which performance could be improved.



•

Our Board addresses the importance of incorporating new viewpoints on the Board through the director evaluation and nomination process. Our director composition reflects a mix of tenure on the Board (ranging from three yearsless than one year to 1820 years), which we believe provides an effective balance of historical perspective and an understanding of the evolution of the Company with fresh perspectives and insights.



•

Share ownership guidelines are in place for our directors and executive officers.

              Code of Business Conduct and Ethics.    We have adopted a Code of Business Conduct and Ethics that applies to all of our directors, officers (including our CEO, chief financial officer, controller and any person performing similar functions) and employees. Our Code of Business Conduct and Ethics contains written standards designed to communicate our expectations of our directors, officers, and employees when making decisions and conducting themselves in corporate activities, including the ethical handling and use of confidential information; actual or apparent conflicts of interest; compliance with applicable governmental laws, rules and regulations; protection of our assets and proprietary information; the ethical handling of payments and gifts received in the normal course of business and of payments made to government personnel; prompt internal reporting of violations of our Code of Business Conduct and Ethics; and accountability for adherence to our Code of Business Conduct and Ethics. We have established a means for individuals to report a violation or suspected violation of the Code of Business Conduct and Ethics anonymously, including those violations relating to accounting, internal controls or auditing matters, and federal securities laws. We intend to satisfy the disclosure requirements regarding any amendment to, or waiver from, a provision of the Code of Business

Table of Contents

Conduct and Ethics by making disclosures concerning such matters available on our website at www.insmed.com under the heading "Investor Relations—"Investors—Corporate Governance."

Table of Contents

              Corporate Governance Guidelines.    We have adopted Corporate Governance Guidelines to assist and guide the Board in the exercise of its responsibilities and establish a framework for our corporate governance practices. The Corporate Governance Guidelines contain written standards pertaining to director qualifications, director responsibilities, structure of our Board, director access to management and independent advisors, director compensation, and performance evaluation of our Board and committees, among other things. The Corporate Governance Guidelines help to ensure that the Board is independent from management, the Board adequately performs its oversight functions, and the interests of the Board and management align with the interests of our shareholders. Our Corporate Governance Guidelines are interpreted in accordance with all applicable laws and regulations, the Nasdaq listing standards, and our Articles of Incorporation and our Bylaws.

              Meetings of the Board.    The Board held eleven10 meetings during 2017.2019. Each director attended at least 75% of the aggregate number of Board meetings that occurred in 2017. Each director attended at least 75% of theand committee meetings that occurred in 20172019 during his or her tenure on such committees.the Board.

              Director Resignation Policy.    Any nominee for director in an uncontested election who has a greater number of votes "withheld" from his or her election than votes cast "for" his or her election must submit his or her resignation to the Board promptly following certification of the election results. Within 90 days after the date of the certification of the election results, the Nominations and Governance Committee will make a recommendation to the Board as to whether to accept or reject the submitted resignation. Within 45 days after receiving this recommendation, the Board must accept or reject the resignation or pursue another action unless doing so would cause us to fail to comply with federal or state law or Nasdaq listing standards. If more than a majority of the members of the Nominations and Governance Committee do not receive a greater number of votes cast "for" their election than votes "withheld," the independent directors whose classes were not nominated for election will appoint a special committee to consider the resignations and make a recommendation to the Board. Any director whose resignation is under consideration will not participate in any deliberation or vote regarding his or her resignation. If the Board accepts a director's resignation pursuant to this policy, the Board may decrease the size of the Board or fill the resulting vacancy in accordance with the Virginia Stock Corporation Act and our Articles of Incorporation and Bylaws.

              Independence of the Directors and Director Nominees.Directors.    The Board makes an affirmative determination regarding the independence of each director annually, based on the recommendation of the Nominations and Governance Committee. The Board has determined that the following members of the Board are independent, as that term is defined under the general independence standards of the Nasdaq listing standards: Mr. Altomari, Mr. Brennan, Dr. Desjardins, Dr. Engelsen, Mr. Hayden, Mr. McGirr, Ms. Potter,Anderson, Dr. Sharoky and Dr. Sharoky.Mr. Lee. Mr. Lewis is not considered independent because he is currently employed by the Company. The Board makesalso determined that Mr. Hayden, who resigned as a director in May 2019, was an affirmative determination regarding the independence of each director annually, based on the recommendation of the Nominations and Governance Committee.independent director.

              Board's Role in Strategy.    The Board actively participates in Company strategy decisions and oversight throughout the year. The Board annually reviews the company's strategic plan, including key risks and decisions facing the company.Company.

Director Nominating Process

              Our Nominations and Governance Committee, which is described more fully below under "Corporate Governance—Committees of the Board—Nominations and Governance Committee," serves as an independent and objective party to identify, assess, recruit and recommend to the Board qualified candidates for directorship, consistent with criteria approved by the Board, and establishes and annually

Table of Contents

reviews such criteria based on factors it considers appropriate. The Board evaluates each nominee in the context of the Board as a whole, with the objective of recommending a group of directors that can best oversee the business and affairs of the Company and use its diversity of experience to represent shareholder interests through the exercise of sound judgment. The Board seeks director nominees with experience in the pharmaceutical and biotechnology industries, as well as business, management, accounting and financial experience, among other areas. Among the factors that the Board and the Nominations and Governance Committee consider are strength of character, sound business

Table of Contents

judgment, career specialization, relevant technical skills, diversity, independence, the ability to commit sufficient time to the Board, and the extent to which the candidate would fill a present need ofon the Board.Board, along with geographic, gender, age, racial and ethnic diversity.

Nominations and Governance Committee Process for Identifying and Evaluating Director Candidates. The Nominations and Governance Committee evaluates all director candidates in accordance with the director qualification standards described in the Corporate Governance Guidelines and seeks candidates with experience in the pharmaceutical and biotechnology industries, as well as business, management, accounting and financial experience.above. The Nominations and Governance Committee evaluates a candidate's qualifications to serve as a member of the Board based on the skills and characteristics of such individual Board members,member, as well as the composition of the Board as a whole. In addition, the Nominations and Governance Committee will evaluate a candidate's independence, diversity, skills and experience in the context of the Board's needs.

              Director Candidate Recommendations and Nominations by Shareholders.    The Nominations and Governance Committee's charter provides that the committee will consider director candidate recommendations by shareholders. Shareholders should submit any such recommendations for the Nominations and Governance Committee through the method described below under "Corporate Governance—Communications with the Board." In accordance with our Bylaws, any person who is a shareholder of record on the record date for the shareholder meeting, on the date of the shareholder meeting, and on the date such person provides required notice to the Company may nominate persons for election to the Board if such shareholder complies with the notice procedures set forth in the Bylaws and summarized in this Proxy Statement under the heading "Proposals for 20192021 Annual Meeting."

Communications with the Board

              The Board has approved a process for shareholders to send communications to the Board. Shareholders can send communications to the Board and, if applicable, to the Nominations and Governance Committee or to specified individual directors in writing c/o Ms. Christine Pellizzari, Corporate Secretary, Insmed Incorporated, 10 Finderne Avenue, Building 10,700 US Highway 202/206, Bridgewater, New Jersey, 08807. All communications sent to Ms. Pellizzari will be forwarded, as appropriate, to the Board, the Nominations and Governance Committee or any specified individual directors.

Director Attendance at Annual Meeting

              Our policy is that directors are expected to make reasonable efforts to attend the annual meeting of shareholders absent unusual circumstances. All directors then on the Board, including Mr. Hayden, attended the 20172019 Annual Meeting of Shareholders.

Board Leadership Structure

              The Board believes that it is in the best interests of the Company to maintain the flexibility to make determinations about the separation of the positions of Board Chair and CEO. The Nominations and Governance Committee considers this structure as part of its annual review of the size, organization, structure, composition and operations of the Board and its committees. In November

Table of Contents

2018, Mr. Hayden stepped down as Chairman of the Board and was succeeded by Mr. Lewis. Mr. Lewis continued as President and CEO of the Company and Mr. Brennan was elected as Lead Independent Director. The Board believes that its current leadership structure, with Mr. Lewis serving as CEO and Chairman and Mr. HaydenBrennan serving as our independent non-executive Chairman,Lead Independent Director, is appropriate for the Company at this time. Both Mr. Lewis and Mr. HaydenBrennan are actively engaged on significant matters affecting us, such as long-term strategy. The CEO has overall responsibility for all aspects of our operation, while the ChairmanLead Independent Director has a greater focus on governance of the Company, including oversight of the Board. We believe this balancethe combined role of CEO and Chairman balanced with the shared leadership betweenwith the two positionsLead Independent Director is a strength for the Company. As our independent non-executive Chairman,Lead Independent Director, Mr. HaydenBrennan calls and chairs regular and special meetings of the Board and all

Table of Contents

executive sessions of the independent directors, chairs and presides at annual or special meetings of shareholders, provides meaningful input into the agenda of Board meetings, oversees the retention of outside advisors, consultants and legal counsel who report directly to the Board, consults frequently with committee chairs and management and has the right to and often does attend Board committee meetings.

Committees of the Board

              Our Bylaws provide that the Board may create one or more committees of the Board. Currently, the Board has threefour standing committees: the Audit Committee, the Compensation Committee, and the Nominations and Governance Committee and the Science and Technology Committee.

Audit Committee

              Composition and Attendance.    Our Audit Committee consists of Mr. McGirr (Chairman), Dr. Engelsen, and Mr. Altomari, each of whom is an independent Board member. During 2017,2019, the Audit Committee held sixseven meetings. Each of Mr. McGirr, Dr. Engelsen and Mr. Altomari attended all meetings of the Audit Committee held in 2017.

              Responsibilities and Duties.    The Audit Committee assists our Board in fulfilling its oversight responsibilities relating to the accounting, reporting and financial practices of the Company and seeking to ensureas well as overseeing our compliance with applicable legal and regulatory requirements. The Committee reviews and oversees:

•

the auditing, accounting, and financial statements,reporting processes, including the audits of our financial reports and other financial information that we provide to governmental bodies, our shareholders and others;statements;



•

our systems of internal controls regarding finance and accounting;



•

our auditing, accounting and financial reporting processes;that we have established;



•

the qualifications and independence of our independent registered public accounting firm; and



•

the engagementappointment, retention and compensationperformance of our independent registered public accounting firm to performand the performance of any internal audit servicesfunctions; and any permissible non-audit services.



•

our compliance with legal and regulatory requirements.

              The Audit Committee reviews and reassesses the adequacy of its charter at least annually.

              Committee Independence.    Our Board has determined that all three of the current Audit Committee members, Mr. McGirr, Dr. Engelsen, and Mr. Altomari, satisfy the heightened independence requirements of the Nasdaq listing standards and Rule 10A-3 under the Securities Exchange Act of 1934, as amended (the Exchange Act).

Table of Contents

              Financial Literacy and Expertise.    Our Board determined that each of the members of the Audit Committee is able to read and understand fundamental financial statements, including our consolidated balance sheet, statement of comprehensive income/loss, statement of cash flows, and statement of shareholders' equity. Our Board also has determined that Mr. McGirr is an "audit committee financial expert," as that term is defined in the rules promulgated by the SEC and has accounting or related financial management expertise as required under the Nasdaq listing standards.

Table of Contents

Compensation Committee

              Composition and Attendance.    Our Compensation Committee consists of Mr. Altomari (Chairman)(Chair), Mr. Brennan, Ms. Potter, and Dr. Sharoky,Mr. Lee, each of whom is an independent Board member. During 2017,2019, the Compensation Committee held seven meetings. Each of Mr. Altomari, Mr. Brennan, and Dr. Sharoky attended all Compensation Committee meetings held in 2017 and Ms. Potter attended six of the Compensation Committee meetings held in 2017.

              Responsibilities and Duties.    The Compensation Committee develops and oversees the implementation of our compensation philosophy for our executive officers and is responsible for our executive and other compensation plans. The Compensation Committee's primary objectives are to develop and maintain an executive compensation program that:

•

creates a direct relationship between pay levels and corporate performance and returns to shareholders;



•

provides overall competitive pay levels to effectively attract and retain executive talent;



•

creates proper incentives to enhance shareholder value; and



•

rewards performance.

              The Compensation Committee reviews and reassesses the adequacy of its charter at least annually.

              Committee Independence and Related Requirements.    Our Board has determined that all fourthree of the current Compensation Committee members, Mr. Altomari, Mr. Brennan, Ms. Potter and Dr. Sharoky,Mr. Lee satisfy the heightened independence requirements of the Nasdaq listing standards. In addition, all of the members of our Compensation Committee are "non-employee directors" within the meaning of the rules under Section 16 of the Exchange Act and "outside directors" for purposes of Section 162(m) of the Internal Revenue Code of 1986, as amended (the Code and Section 162(m)). The Board has determined that Mr. Sharoky also satisfied these independence and related requirements during his tenure on the Compensation Committee.

Nominations and Governance Committee

              Composition and Attendance.    Our Nominations and Governance Committee consists of Dr. Engelsen (Chairman), Mr. Hayden,Ms. Anderson (Chair) and Dr. Sharoky, each of whom is an independent Board member. During 2017,2019, the Nominations and Governance Committee held sixfour meetings. Each of Dr. Engelsen, Mr. Hayden, and Dr. Sharoky attended all meetings of the Nominations and Governance Committee held in 2017 during their tenure on the Nominations and Governance Committee.

              Responsibilities and Duties.    The Nominations and Governance Committee identifies and nominates qualified candidates for directorship and serves in a leadership role in shaping our corporate

Table of Contents

governance and overseeing the evaluation of the Board and its committees. The Nominations and Governance Committee:

•

assists the Board by identifying individuals qualified to become Board members and recommending to the Board the director nominees for election at shareholder meetings and to fill vacancies on the Board;



•

makes recommendations to the Board regarding Board and committee organization, structure and composition;

Table of Contents

•

evaluates the overall effectiveness of the Board and its committees; and



•

develops implements and assesses the Company's corporate governance policies and practices, including risks related to such policies and practices.

              The Nominations and Governance Committee reviews and reassesses the adequacy of its charter at least annually.

Science and Technology Committee

              Composition and Attendance.    Our Science and Technology Committee consists of Dr. Engelsen (Chair), Dr. Sharoky, and Mr. Lee, each of whom is an independent Board member. The Science and Technology Committee was formed in May 2019 and held four meetings.

              Responsibilities and Duties.    The Science and Technology Committee assists our Board in its oversight of the Company's preclinical research and development (R&D) activities and its clinical development activities and decisions. The Science and Technology Committee:

•

reviews with the Company the third-party competitive landscape related to the Company's preclinical R&D and clinical development activities;



•

monitors and identifies significant new and emerging trends in science and technology, including R&D, and provides strategic advice to the Board regarding such issues and trends;



•

reviews with the Company current and planned technology initiatives and provides feedback to the Board regarding such initiatives;



•

advises the Board on the scientific aspects of business development transactions; and



•

assists the Company in reviewing, as requested, the capabilities of the Company's current and prospective key scientific personnel and the depth and breadth of the Company's scientific resources.

              The Science and Technology Committee reviews and reassesses the adequacy of its charter at least annually.

The Role of the Board in Risk Oversight

              The Board has primary responsibility for overseeing the Company's risk management. The Board administers its oversight responsibility for risk management directly and through its committees.

Table of Contents

Each committee chairman reports to the Board regarding the committee's considerations of management's processes for identifying, evaluating, and controlling significant risks. In addition, the officers responsible for oversight of particular risks within the Company provide updates and information to our Board. The Board considers specific risk topics, including risks associated with our strategic plan, our capital structure, our research and development activities, our manufacturing and supply chain, and our operations. Our Board believes that full and open communication between management and the Board is essential for effective risk management and oversight. The Board and each of its committees have full access to our senior management, as well as the ability to engage outside advisors and other experts. Management routinely informs the Board of developments that could affect our risk profile or other aspects of our business and development.

              The Audit Committee is responsible for overseeing the Company's program for identifying, evaluating and controlling significant risks. The Audit Committee periodically discusses with management and the independent auditor our policiesthe Company's major risk exposures, including financial, legal, regulatory and guidelines regarding risk assessment and risk management as well as our major financial and operationalcybersecurity risk exposures, and the steps that management has taken to monitor, control and controlminimize such exposures. The Audit Committee also reviews and evaluates our processes and policies for identifying and assessing key risk areas and for formulating and implementing steps to address such risk areas. The Audit Committee oversees disclosure controls and procedures, including applicable internal control over financial reporting and meets with the Chief Financial Officer, the Chief Legal Officer, the Chief Compliance Officer, the Vice President of Quality Assurance, the Vice President, Corporate Controller,Chief Accounting Officer, external audit personnel, and other senior managers as appropriate to review issues regarding compliance with the applicable legal and regulatory requirements.

              The Compensation Committee assesses and monitors whether any of our compensation policies and programs has the potential to encourage excessive risk taking. Our Compensation Committee engages an independent consultant to advise it on topics related to Board and executive compensation. DuringIn July 2019, the last year,Company selected Willis Towers Watson as its new independent compensation consultant. In February 2019, the Compensation Committee, with the assistance of Frederic W. Cook & Co., Inc. (FW Cook), itsthe Company's former independent compensation consultant, reviewed the executive compensation program and determined that the design of the compensation policies, including the components, weightings and focus of the elements of executive compensation, do not encourage management to assume excessive or inappropriate risks.

              The Nominations and Governance Committee oversees the risks associated with our corporate governance and operating practices, including those relating to the composition of the Board, the structure and function of Board committees and meeting logistics and policies. The Nominations and Governance Committee regularly reviews the Board's performance, oversees the self-evaluation of each of the Board's committees, oversees our corporate governance and formulates and recommends corporate governance standards to our Board.

              The Science and Technology Committee oversees the Company's efforts related to clinical activities, R&D, business development and intellectual property. The Science and Technology Committee reviews the competitive landscape related to the Company's preclinical R&D and research activities and advises the Board on the scientific aspects of business development transactions.

Table of Contents

AUDIT COMMITTEE REPORT*REPORT AND INDEPENDENT AUDITOR FEES

Report of the Audit Committee

              The Audit Committee approves the selection of the Company's independent registered public accounting firm and regularly meets with and holds discussions with management and the Company's independent registered public accounting firm.

              The Audit Committee oversees the Company's financial reporting process on behalf of the Board. 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 the audited financial statements in the Company's Annual Report on Form 10-K for the year ended December 31, 20172019 (the Annual Report) with management, including a discussion of the quality, the accounting principles, the reasonableness of significant judgments, and the quality and clarity of disclosures in the financial statements.

              The Audit Committee reviewed with Ernst & Young, which is responsible for expressing an opinion on the conformity of those audited financial statements with generally accepted accounting principles, its judgments as to the overall quality of financial reporting, the Company's accounting principles, and such other matters as are required to be discussed with the Audit Committee by Public Company Accounting Oversight Board (PCAOB) standards.

              In addition, the Audit Committee has discussed with Ernst & Young its independence from management and the Company, including the matters described in the written disclosures and letter required by PCAOB standards from Ernst & Young to the Audit Committee regarding the independent accountant's communications with the Audit Committee concerning independence, and has considered the compatibility of non-audit services with the independence of the independent registered public accounting firm.

              In reliance on the reviews and discussions referred to above, the Audit Committee recommended to the Board (and the Board approved) that the audited financial statements be included in the Company's Annual Report for filing with the SEC.

THE AUDIT COMMITTEE

David W.J. McGirr, Chairman
Alfred F. Altomari
Steinar J. Engelsen, M.D., C.E.F.A.

*

The foregoing report of the Audit Committee is not to be deemed "soliciting material" or deemed to be "filed" with the SEC (irrespective of any general incorporation language in any document filed with the SEC) or subject to Regulation 14A of the Exchange Act, or to the liabilities of Section 18 of the Exchange Act, except to the extent we specifically incorporate the text of such report by reference into a document filed with the SEC.

Table of Contents

Audit Committee Pre-Approval Policy

              The Audit Committee has adopted an Audit Committee Pre-Approval Policy for the pre-approval of audit services and permitted non-audit services by the Company's independent registered public accounting firm in orderan effort to assureensure that the provision of such services does not impair the independence of the independent registered public accounting firm from the Company and is consistent with the rules of the SEC. The policy requires pre-approval by the Audit Committee of the terms and fees of all audit, review and attestation engagements and related services. The policy also requires the Audit Committee to determine thatpre-approve the provision of any audit-related services or non-audit services and determine they would not impair the independence of our independent registered public accounting firm. The policy also prohibits the Audit Committee from retaining our independent registered public accounting firm in connection with a transaction initially recommended by such firm, the purpose of which may be tax deferral or reduction. The policy delegates pre-approval authority to the Chair of the Audit Committee or, if the Chair is not available, to any of the Audit Committee's members, but any pre-approval decision must be reported to the Audit Committee at its next scheduled meeting. All of the services performed by Ernst & Young in the year ended December 31, 20172019 were pre-approved in accordance with the applicable pre-approval policy.

Independent Registered Public Accounting Firm Fee Disclosure

              The Audit Committee reviewed the aggregate fees billed by Ernst & Young for professional services rendered for the years ended December 31, 20172019 and 2016,2018, which were as follows:

              Audit fees in 20172019 and 20162018 include fees for services performed to comply with generally accepted auditing standards. These services include the quarterly reviews, the integrated year-end audit of our consolidated financial statements, attestation services with respect to our internal control over financial reporting, review of documents filed with the SEC,quarterly reviews, accounting consultations on matters addressed during the audit or quarterly reviews, review of documents filed with the SEC, and $125,000, with respect to 2017, $100,0002019, and $115,000, with respect to 2018, paid to Ernst & Young for consent and comfort letter procedures for registration statements filed in 2017.2019 and 2018, respectively.

CERTAIN RELATIONSHIPS AND RELATED PARTY TRANSACTIONS

Review and Approval of Related Party Transactions

              Pursuant to our written related party policy, our Audit Committee must review and consider whether to approve or ratify all related party transactions, as defined in Item 404 of Regulation S-K. In determining whether to approve or ratify a related party transaction, the Audit Committee will take into account, among other factors it deems appropriate, the purpose and potential benefits to us of the transaction, the related party's interest in the transaction, the approximate dollar value involved in the transaction, whether the transaction was undertaken in the ordinary course of business, whether the related party transaction is on terms no less favorable to us than terms generally available to us from an unaffiliated third-party under the same or similar circumstances, and whether, under all the

Table of Contents

circumstances, the transaction is not inconsistent with our best interests. Any transaction which is

Table of Contents

deemed to be a related party transaction requires the approval of a majority of the disinterested Audit Committee members.

Related Party Transactions

              Since January 1, 2017,2019, there were no related party transactions, nor are there currently any proposed related party transactions, which in accordance with SEC rules, would require disclosure in this Proxy Statement.

DELINQUENT SECTION 16(a) BENEFICIAL OWNERSHIP REPORTING COMPLIANCEREPORTS

              Section 16(a) of the Exchange Act requires that our directors, executive officers and holders of more than 10% of our Common Stock report to the SEC their ownership of our Common Stock and changes in that ownership. Directors, executive officers and beneficial owners of more than 10% of our Common Stock are required by applicable regulations to furnish us with copies of all Section 16(a) forms they file. As a matter of practice, members of our staff assist our executive officers and directors in preparing initial ownership reports and reporting ownership changes and typically file these reports on their behalf. Based solely upon a review of the reports filed pursuant to Section 16(a) of the Exchange Act, we believe that during the year ended December 31, 2017,2019, our executive officers, directors and beneficial owners of more than 10% of our Common Stock complied with applicabletimely filed all reports required under Section 16(a) requirements.16, except for the following instances: (1) on May 16, 2019, Mr. Lee filed a Form 3 that inadvertently omitted 10,000 shares of our Common Stock that Mr. Lee held at the time of his appointment as a director, which shares were subsequently reported on an amended Form 3 filed on March 27, 2020, (2) on February 27, 2019, Mr. Hayden filed a late Form 4 reporting the exercise of options to purchase shares of our Common Stock, and the subsequent sale of such shares, on February 15, 2019, due to a broker error in notifying the Company and Mr. Hayden of the transaction, and (3) on June 12, 2019, Mr. Goll filed a Form 3 that inadvertently omitted options to purchase shares of our Common Stock, which options were subsequently reported on an amended Form 3 filed on November 20, 2019.

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS, DIRECTORS AND MANAGEMENT

              The following tables set forth information about the beneficial ownership of our Common Stock as of the Record Date (except as otherwise noted), by:

•

each person, or group of persons, who beneficially owns more than five percent (5%) of our Common Stock, based on reports filed with the SEC;SEC pursuant to Section 13(d) of the Exchange Act;



•

each of our directors and director nominees;



•

each of our named executive officers; and



•

all directors and executive officers as a group.

              Beneficial ownership and percentage ownership are determined in accordance with Section 13 of the Exchange Act and related rules and regulations of the SEC. In computing the number of shares beneficially owned by a person and the percentage ownership of that person, shares of Common Stock subject to options held by that person that are currently exercisable or exercisable within 60 days of the

Table of Contents

Record Date and restricted stock units that may vest within 60 days of the Record Date are deemed outstanding. Such shares, however, are not deemed outstanding for the purposes of computing the percentage ownership of any other person. Except as indicated in the footnotes to the following tables or pursuant to applicable community property laws, to our knowledge each shareholder named in the tables has sole voting and investment power with respect to the shares set forth opposite such

Table of Contents

shareholder's name. As of the Record Date, there were 76,623,13689,859,549 shares of Common Stock outstanding.

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

PROPOSAL NO. 2

ADVISORY VOTE ON THE 20172019 COMPENSATION OF OUR NAMED EXECUTIVE OFFICERS

Information Regarding the Advisory Vote on the 20172019 Compensation of our Named Executive Officers

              As required pursuantPursuant to Section 14A of the Exchange Act, we are holding a shareholder advisory vote on the compensation of our named executive officers, as described in the "Compensation Discussion and Analysis" section, the tabular disclosure regarding such compensation, and the accompanying narrative disclosure set forth in this Proxy Statement. At the 2017 Annual Meeting, shareholders voted to hold advisory votes on an annual basis, and the Board subsequently adopted a resolution providing for such an annual vote. At the Annual Meeting, shareholders will be asked to approve the following resolution:

              RESOLVED, that the shareholders of Insmed Incorporated approve, on an advisory basis, the compensation of the Company's named executive officers, disclosed pursuant to Item 402 of Regulation S-K in the Company's Proxy Statement.

              The Compensation Committee oversees and administers our executive compensation program, including the evaluation and approval of compensation plans, policies and programs offered to our named executive officers. Our executive compensation program is designed to meet the following objectives:

•

align management interests with the interests of our shareholders;



•

emphasize use of "at-risk" and performance-based compensation to motivate executives to advance our interests; and



•

provide executive compensation packages that are competitive in order to attract and retain executives whose skills are critical to the current and long-term success of the Company.

              Please read the "Compensation Discussion and Analysis" section starting on page 2732 of this Proxy Statement for a detailed discussion about our executive compensation programs, including information about the 20172019 compensation of our named executive officers.

Vote Required for Approval of this Proposal

              The advisory vote on the compensation of our named executive officers will be approved by the affirmative vote of the majority of votes properly cast in person or by proxy, at the Annual Meeting. Abstentions or broker non-votes will not have an effect on the outcome of this proposal.

              While this vote is being conducted on an advisory basis, and is therefore not binding on us, the vote will be carefully considered by the Compensation Committee and our Board. Both our Compensation Committee and our Board value the opinions of our shareholders and, to the extent there is any meaningful vote against the 2019 compensation of our named executive officers, as disclosed in this Proxy Statement, we will consider our shareholders' concerns and evaluate what actions, if any, may be appropriate to address those concerns. The outcome of the vote, however, will not be construed as overruling any prior decision by the Company, the Compensation Committee or the Board.

Recommendation

              THE BOARD RECOMMENDS THAT YOU VOTE "FOR" THE APPROVAL, ON AN ADVISORY BASIS, OF THE 20172019 COMPENSATION OF OUR NAMED EXECUTIVE OFFICERS.

Table of Contents

EXECUTIVE COMPENSATION
COMPENSATION DISCUSSION AND ANALYSIS

              This Compensation Discussion and Analysis (the CD&A) explains our compensation philosophy, policies and decisions for 20172019 for the following executives, whom we refer to in this CD&A and in the following tables as our named executive officers:

1.

William H. Lewis, President and CEO, responsible for developing, in connection with the Board, our corporate mission and objectives and providing direction and leadership to ensure the execution of our corporate strategy and achievement of our objectives. Mr. Lewis was appointed as our Chairman in November 2018.



2.

Paolo Tombesi, Chief Financial Officer, responsible for managing all financial and technical operations activities, including internal and external reporting, treasury, accounting, tax, investor relations, manufacturing and supply chain.



3.

Roger Adsett, Chief CommercialOperating Officer, responsible for managing all globaloversight of overall business operations, including marketing, sales and commercial activities, technical operations and supply chain activities.



4.3.

Paul Streck, M.D.John Goll, Chief MedicalAccounting Officer, responsible for leading global research, clinical development, clinical operations, regulatory affairs, drug safety and pharmacovigilance, and medical affairs.served as our principal financial officer from July 2019 to January 2020.



5.4.

Christine Pellizzari, Chief Legal Officer, responsible for oversight of all corporate and litigation-related legal matters, global compliancegovernment affairs and for providing ongoing legal support for development,with respect to regulatory strategy, financing opportunities, business development initiatives, and intellectual property matters.



5.

S. Nicole Schaeffer, Chief People Strategy Officer, responsible for all aspects of human resources and corporate services inclusive of organizational and leadership development, total compensation and employee communications, facilities, environmental health and safety, and information technology.



6.

Andrew T. DrechslerPaolo Tombesi, former Chief Financial Officer. Mr. Drechsler announcedOfficer, stepped down as our Chief Financial Officer and his resignation in November 2016 and leftemployment with the Company in March 2017.ended on June 2, 2019.

Executive Summary of Our 20172019 Business and Strategic Achievements

              We are a global biopharmaceutical company focused on a mission to transform the unmet needslives of patients with serious and rare diseases. Our leadfirst commercial product, candidate is amikacinARIKAYCE (amikacin liposome inhalation suspension (ALIS) (formerly known as liposomal amikacinsuspension), received accelerated approval in the United States (US) in September 2018 for inhalation), which is in late-stage development for adult patients withthe treatment refractory nontuberculous mycobacteria (NTM) lung disease caused byofMycobacterium avium complex (MAC), lung disease as part of a combination antibacterial drug regimen for adult patients with limited or no alternative treatment options in a refractory setting, as defined by patients who do not achieve negative sputum cultures after a minimum of six consecutive months of a multidrug background regimen therapy. Nontuberculous mycobacterial (NTM) lung disease caused by MAC (which we refer to as MAC lung disease) is a rare and often chronic infection that can cause irreversible lung damage and can be fatal. Our earlier clinical-stage pipeline includes INS1007 and INS1009. INS1007 is a novel oral, reversible inhibitor of dipeptidyl peptidase 1 (DPP1), an enzyme responsible for activating neutrophil serine proteases, which are implicated

              In 2019, our named executive officers played critical roles in the pathologyfurtherance of chronic inflammatoryour mission. We successfully completed our first year of commercialization and observed strong performance in the US launch of ARIKAYCE. In July 2019, we filed a marketing authorization application (MAA) with the European Medicines Agency (EMA) for ARIKAYCE for the treatment of patients with persistent MAC lung diseases, such as non-cystic fibrosis (non-CF) bronchiectasis. INS1009 is an inhaled nanoparticle formulationinfection, and the filing was subsequently validated. In 2019, we also advanced our Japanese new drug application (JNDA), resulting in the submission of the JNDA to Japan's Ministry of Health, Labour and Welfare (MHLW) in March 2020 for ARIKAYCE for the treatment of patients with MAC lung disease who do not respond sufficiently to prior treatment.

Table of Contents

              We also have a treprostinil prodrug that may offer a differentiatedrobust pipeline which includes the following product profile for rare pulmonary disorders, including pulmonary arterial hypertension (PAH). Our earlier-stage pipeline includes preclinical compounds that we are evaluating in multiple rare diseases of unmet medical need, including methicillin-resistant staph aureus and NTM.candidates:

              To complement our internal research and development, we actively evaluate in-licensing and acquisition opportunities for a broad range of rare diseases.

              In 2017, our named executive officers played critical rolesMay 2019, we completed enrollment of patients in achieving several key strategic steps toward our goalthe WILLOW study, a global randomized, double-blind, placebo-controlled Phase 2 clinical study evaluating the efficacy, safety and pharmacokinetics of building a commercial biopharmaceutical company. WeINS1007 administered once daily for 24 weeks in adults with non-CF bronchiectasis. In February 2020, we announced positive top-line results from the phase 3 CONVERT study of ALISWILLOW study.

              More broadly from a strategic and operational standpoint, in patients with NTM lung disease, advanced the WILLOW study of INS1007 in patients with non-CF bronchiectasis, and2019 we expanded our

Table of Contents

leadership team with talented executives in key finance,financial, medical, commercial, sales, and clinical and investor relations roles. When determining payouts for the annual cash incentives, the Board, with respect to our President and CEO, and the Compensation Committee, with respect to the other named executive officers, took into account these and other achievements in the evaluation of our performance against our annual corporate objectives.