UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

Filed by the Registrant ☒       Filed by a partyParty other than the Registrant ☐

Check the appropriate box:

Frequency Therapeutics,Korro Bio, Inc.

(Name of Registrant as Specified in itsIts Charter)

(Name of Person(s) Filing Proxy Statement, if Other Thanother than the Registrant)

Payment of Filing Fee (Check the appropriate box)all boxes that apply):

Frequency Therapeutics, Inc.One Kendall Square, Building 600-700, Suite 6-401

75 Hayden Avenue

Lexington,Cambridge, MA 0242102139

NOTICE OF 2024 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON JUNE 17, 2021To Be Held on June 11, 2024

NOTICE HEREBY IS GIVEN thatDear Stockholders:

You are cordially invited to virtually attend the 2024 annual meeting of stockholders, or the Annual Meeting, of Stockholders of Frequency Therapeutics,Korro Bio, Inc., a Delaware corporation, will be held on Thursday, June 17, 2021 at 9:00 a.m. Eastern Time. In light of the public health and travel safety concerns related to the ongoing coronavirus (COVID-19) pandemic and after careful consideration, the The Annual Meeting will be a completely virtual meeting and will be held via live webcast. Thethe Internet at a virtual audio web conference at https://www.proxydocs.com/KRRO on Tuesday, June 11, 2024 at 1:30 p.m., Eastern time. You must register to attend the meeting is being held foronline at www.proxydocs.com/KRRO no later than June 10, 2024 at 5:00 p.m. Eastern Time.

Only stockholders who owned shares of our common stock at the close of business on April 12, 2024 are entitled to notice of and to vote at the Annual Meeting or any adjournment thereof. At the Annual Meeting, the stockholders will consider and vote on the following purposes, as more fully described in the accompanying proxy statement.

The Annual Meeting is being held:matters:

These itemsThe Annual Meeting will be a “virtual meeting” of business are described instockholders, which will be conducted exclusively via the Proxy Statement that follows this notice. Holders of record of our common stock as of the close of business on April 19, 2021 are entitledInternet at a virtual web conference. There will not be a physical meeting location, and stockholders will not be able to notice of and to vote atattend the Annual Meeting or any continuation, postponement or adjournment thereof. A complete list of such stockholders will be openin person. This means that you can attend the Annual Meeting online, vote your shares during the online meeting and submit questions during and shortly before the online meeting. In order to attend the examination of any stockholdermeeting and vote your shares electronically during the meeting, you must register in advance at our principal executive offices at 75 Hayden Avenue, Lexington, MA 02421 for a period of ten dayswww.proxydocs.com/KRRO prior to the Annual Meeting. Thedeadline of Wednesday, June 10, 2024 at 5:00 p.m., Eastern time. Upon completing your registration, you will receive further instructions via email, including your unique links that will allow you to attend the Annual Meeting, may be continued or adjournedvote your shares and submit questions. We believe that hosting a “virtual meeting” will enable greater stockholder attendance and participation from time to time without notice other than by announcement atany location around the Annual Meeting.world.

Please seeYou can find more information, including the “General Information” section ofnominees for director, in the proxy statement that accompanies this notice for more details regarding the logistics of the virtual Annual Meeting, including the ability of stockholders to submit questions during the Annual Meeting, which is available for viewing, printing and technical detailsdownloading at www.proxydocs.com/KRRO. The board of directors recommends that you vote “FOR” each of the Class II directors (Proposal 1), “FOR” the amendment of our Restated Certificate of Incorporation (Proposal 2) and support related“FOR” the ratification of the appointment of the proposed independent registered public accounting firm (Proposal 3) as outlined in the attached proxy statement.

We are pleased to accessingcomply with the virtual platform.rules of the Securities and Exchange Commission, or SEC, that allow companies to distribute their proxy materials over the Internet under the “notice and access” approach. As a result, we are sending to our stockholders a Notice of Internet Availability of Proxy Materials, or the Notice of Availability, instead of a paper copy of this proxy statement and our annual report for the fiscal year ended December 31, 2023, or the 2023 Annual Report. We will mail the Notice of Availability on or about     , 2024, and the Notice of Availability contains instructions on how to access our proxy materials over the Internet. The Notice of Availability also contains instructions on how each of our stockholders can receive a paper copy of our proxy materials, including the proxy statement, our 2023 Annual Report, and a form of proxy card.

Your vote is important. Votingimportant regardless of the number of shares you own. Whether or not you expect to virtually attend the Annual Meeting online, please vote your shares willto ensure your representation and the presence of a quorum at the Annual Meeting and will save us the expenseMeeting. If you are a stockholder of further solicitation. Please promptlyrecord, you may vote your shares prior to the Annual Meeting on the Internet by visiting www.proxypush.com/KRRO, by telephone by calling +1 866-390-5362 and following the recorded instructions, for votingor by completing, signing, dating, and returning a proxy card. If you mail your proxy card or vote by telephone or the Internet and then decide to attend the Annual Meeting and vote your shares online during the Annual Meeting, you may still do so. Your proxy is revocable in accordance with the procedures set forth in the proxy statement.

If your shares are held in “street name,” that is, held for your account by a bank, broker or telephone votingother nominee, you will receive instructions from the bank, broker or other nominee that you must follow for your shares to be voted. Stockholders that hold shares in “street name” must demonstrate proof of beneficial ownership to virtually attend the Annual Meeting and must obtain a legal proxy from their bank, broker or other nominee to vote during the Annual Meeting.

A list of stockholders as describedof the close of business on the record date will be available for examination by our stockholders of record during the Annual Meeting using the unique link provided via email following the completion of registration. Further information about how to register for the Annual Meeting, attend the Annual Meeting online, vote your shares and submit questions is included in the accompanying proxy card.statement.

By Order of the Board of Directors,

Ram Aiyar, Ph.D.

President and Chief Executive Officer

Cambridge, MA

   , 2024

Lexington, Massachusetts

April 29, 2021

Important Notice Regarding Internet Availability of Proxy Materials: The attached proxy statement and our 2023 Annual Report, which includes our annual report on Form 10-K for the fiscal year ended December 31, 2023, are available for viewing, printing and downloading at www.proxydocs.com/KRRO. These documents are also available to any stockholder who wishes to receive a paper copy upon written request to Korro Bio, Inc., One Kendall Square, Building 600-700, Suite 6-401, Cambridge, MA 02139. This proxy statement and our annual report on Form 10-K for the fiscal year ended December 31, 2023 are also available on the SEC’s website at http://www.sec.gov.

KORRO BIO, INC.

PROXY STATEMENT

TABLE OF CONTENTS

One Kendall Square, Building 600-700, Suite 6-401

Cambridge, MA 02421

(617) 468-1999

PROXY STATEMENT

FOR2024 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON JUNE 17, 2021To Be Held on June 11, 2024

INFORMATION CONCERNING SOLICITATION AND VOTING

This proxy statement (the “Proxy Statement”)contains information about the Annual Meeting of Stockholders of Korro Bio, Inc., or the Annual Meeting, to be held on Tuesday, June 11, 2024 at 1:30 p.m., Eastern time. The Annual Meeting will be held via the Internet at www.proxydocs.com/KRRO. There will not be a physical meeting location, and stockholders will not be able to attend the Annual Meeting in person. Further information about how to attend the Annual Meeting online is included in this proxy statement.

The board of directors of Korro is using this proxy statement to solicit proxies for use at the Annual Meeting. In this proxy statement, unless expressly stated otherwise or the context otherwise requires, references to “Korro,” “the Company,” “we,” “us,” “our” and similar terms refer to Korro Bio, Inc. References to our website are inactive textual references only and the contents of our website are not incorporated by reference into this proxy statement.

All properly submitted proxies will be voted in accordance with the instructions contained in those proxies. If no instructions are specified, the shares represented by the proxies will be voted in accordance with the recommendation of our board of directors with respect to each of the matters set forth in the accompanying Notice of Meeting. If you are a stockholder of record, you may change your vote or revoke your proxy at any time before it is exercised at the meeting by following the instructions set forth in this proxy statement.

We have elected to provide access to our proxy materials over the Internet under the Securities and Exchange Commission’s, or SEC’s, “notice and access” rules. As a result, we are mailing to our stockholders a Notice of Internet Availability of Proxy Materials, or Notice of Availability, instead of a paper copy of this proxy statement and our annual report for the fiscal year ended December 31, 2020 (the “Annual Report”2023, or the 2023 Annual Report. We are sending the Notice of Availability on or about     , 2024, and togetherit contains instructions on how to access those documents over the Internet. The Notice of Availability also contains instructions on how each of our stockholders can receive a paper copy of our proxy materials, including this proxy statement, our 2023 Annual Report, and a form of proxy card.

Important Notice Regarding the Availability of Proxy Materials for

the Annual Meeting of Stockholders to be Held on June 11, 2023:

This proxy statement and our 2023 Annual Report are

available for viewing, printing and downloading at www.proxydocs.com/KRRO.

A copy of our annual report on Form 10-K for the fiscal year ended December 31, 2023, as filed with the Proxy Statement,SEC except for exhibits, will be furnished without charge to any stockholder upon written request to Korro Bio, Inc., One Kendall Square, Building 600-700, Suite 6-401, Cambridge, MA 02139. This proxy statement and our annual report on Form 10-K for the “proxy materials”)fiscal year ended December 31, 2023 are being furnished by andalso available on behalfthe SEC’s website at http://www.sec.gov.

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IMPORTANT INFORMATION ABOUT THE ANNUAL MEETING AND VOTING

Purpose of the Annual Meeting

At the Annual Meeting, our stockholders will consider and vote on the following matters:

As of the date of this proxy statement, we are not aware of any business to come before the meeting other than the first four items noted above.

Board of Directors (the “BoardRecommendation

Our board of Directors” or “Board”)directors unanimously recommends that you vote:

FOR the election of Frequency Therapeutics, Inc. (the “Company”, “Frequency”, “we,” “us” or “our”) in connection withthe two nominees to serve as Class II directors on our 2021board of directors, each for a three-year term expiring at the 2027 annual meeting of stockholders (the “Annual Meeting”). stockholders;

FOR the approval of the amendment of our Restated Certificate of Incorporation to limit the liability of certain officers as permitted by amendments to Delaware law; and

FOR the ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2024.

Availability of Proxy Materials

The proxy materials, including this proxy statement, a proxy card and our 2023 Annual Report are first being sentavailable for viewing, printing and downloading on or about May 4, 2021the Internet at www.proxydocs.com/KRRO. If you would like to allreceive a paper copy of our proxy materials, you should follow the instructions for requesting paper materials in the Notice of Availability.

Who Can Vote at the Annual Meeting?

Only stockholders of record at the close of business on the record date of April 17, 2024 are entitled to receive notice of the Annual Meeting and to vote the shares of our common stock that they held on that date. As of April 17, 2024, there were 8,023,400 shares of our common stock issued and outstanding. Each share of common stock is entitled to one vote on each matter properly brought before the Annual Meeting.

Difference Between a “Stockholder of Record” and a Beneficial Owner of Shares Held in “Street Name”

Stockholder of Record. If your shares are registered directly in your name with our transfer agent, Computershare Trust Company, then you are considered the “stockholder of record” of those shares. In this case, your Notice of Availability has been sent to you directly by us. You may vote your shares by proxy prior to the Annual Meeting by following the instructions contained in the Notice of Availability and in the section titled “How to Vote” below.

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Beneficial Owner of Shares Held in Street Name. If your shares are held by a bank, broker or other nominee, then you are considered the beneficial owner of those shares, which are held in “street name.” In this case, your Notice of Availability will be sent to you by that organization. The organization holding your shares is considered the stockholder of record for purposes of voting at the Annual Meeting.

In light of As the public health and travel safety concerns relatedbeneficial owner, you have the right to the ongoing coronavirus (COVID-19) pandemic and after careful consideration, the Annual Meeting will be a completely virtual meeting and will be held via live webcast in orderinstruct that organization as to facilitate stockholder attendance and participation by enabling stockholders to participate and vote electronically from any location. Details regarding how to attendvote the meeting online are more fully described below.shares held in your account by following the instructions contained on the voting instruction card provided to you by that organization.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE STOCKHOLDER MEETING TO BE HELD ON THURSDAY, JUNE 17, 2021. AWhy Did I Receive a Notice in the Mail Regarding the Internet Availability of Proxy Materials (the “Notice”) will be mailedinstead of a Full Set of Proxy Materials?

We are pleased to certaincomply with the SEC rules that allow companies to distribute their proxy materials over the Internet under the “notice and access” approach. As a result, are sending our stockholders and beneficial owners of our stockholders. Thecommon stock a copy of the Notice of Availability instead of paper copies of this proxy statement, our proxy card, and our 2023 Annual Report. We will send the Notice of Availability on or about     , 2024.

Detailed instructions on how to access these materials canvia the Internet may be accessed at our Investor Relations website at http://investors.frequencytx.com or by following the instructionsfound in the Notice.Notice of Availability. This proxy statement and our 2023 Annual Report are available for viewing, printing and downloading on the Internet at www.proxydocs.com/KRRO.

General information aboutWhy is the Annual Meeting and Voting

How do I attend the Annuala Virtual, Online Meeting?

The Annual Meeting will be held on Thursday,a virtual meeting of stockholders where stockholders will participate by accessing a website using the Internet. There will not be a physical meeting location. We believe that hosting a virtual meeting will facilitate stockholder attendance and participation at our Annual Meeting by enabling stockholders to safely participate from any location around the world. Our virtual meeting will be governed by our Rules of Conduct and Procedures, which will be posted at www.proxydocs.com/KRRO in advance of the meeting. We have designed the virtual annual meeting to provide our stockholders with the same rights and opportunities to participate as stockholders would have at an in-person meeting, including the right to vote and ask questions during and shortly before the meeting through the virtual meeting platform.

How to Virtually Attend the Annual Meeting

The Annual Meeting will be a virtual meeting and you may not attend in person. In order to attend the meeting online, you must register in advance at www.proxydocs.com/KRRO prior to the deadline of June 17, 202110, 2024 at 9:5:00 a.m.p.m., Eastern Time via a live webcast. Prior registration at www.proxydocs.com/FREQ totime. You may attend the Annual Meeting online by following the instructions that you will receive once your registration is required by 8:59 a.m. Eastern Timecomplete.

Online registration for the Annual Meeting will begin on      Thursday, June 17, 2021 (the “Registration Deadline”). You will need the control number that appears on your proxy card (the “Control Number”) to register to attend the meeting. If your shares are held in “street name,” as described below,, 2024, and you should useallow ample time for the online registration. Upon completing your Control Number provided onregistration, you will receive further instructions via email, including your notice or voting instruction form, or otherwise vote through the bank, broker or other nominee. The meeting webcastunique link that will begin promptly at 9:00 a.m. Eastern Time. We encourageallow you access to access the meeting priorand you will have the ability to submit questions.

Please be sure to following the instructions you will receive once your registration is complete.

The Annual Meeting will start at 1:30 p.m., Eastern time, on June 11, 2024. You may log on to the start time.virtual meeting starting one hour before it begins. We will have technicians standing by and ready to assist you with any technical difficulties you may have accessing the virtual meeting website by callingstarting at 1:15 p.m., Eastern time, on June 11, 2024. If you encounter any difficulties accessing the virtual Annual Meeting, please contact technical support by following the instructions provided to you upon registration for the Annual Meeting.

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How to Vote If you are the stockholder of record of your shares, you can vote your shares by proxy prior to the Annual Meeting or online during the Annual Meeting. If you choose to vote by proxy prior to the Annual Meeting, you may do so by telephone, via the Internet or by mail as follows:

Telephone and Internet voting for stockholders of record will be available until 11:59 p.m. Eastern time on June 10, 2024, and mailed proxy cards must be received by 11:59 p.m. Eastern time on June 10, 2024 in order to be counted at the Annual Meeting. If the Annual Meeting is adjourned or postponed, these deadlines may be extended.

If your shares are held in street name, your bank, broker or other nominee is required to vote the shares it holds on your behalf according to your instructions. The proxy materials, as well as voting and revocation instructions, should have been forwarded to you by the bank, broker or other nominee that holds your shares. In order to vote your shares you will need to follow the instructions that your bank, broker or other nominee provides you. The voting deadlines and availability of telephone and Internet voting for beneficial owners of shares held in “street name” will depend on the voting processes of the bank, broker or other nominee that holds your shares. Therefore, we urge you to carefully review and follow the voting instruction card and any other materials that you receive from that organization. If your shares are held in “street name”, you must demonstrate proof of beneficial ownership to virtually attend the Annual Meeting and must obtain a legal proxy from your bank, broker or other nominee to vote at the Annual Meeting. Only stockholders who have registered to attend the meeting by June 10, 2024 at 5:00 p.m., Eastern time, using the process described above may vote during the meeting. In addition, you will need your control number included on your Notice, proxy card or voting instruction form in order to demonstrate proof of beneficial ownership and to be able to vote during the Annual Meeting.

Even if you plan to attend the Annual Meeting online, we urge you to vote your shares by proxy in advance of the Annual Meeting so that if you should become unable to attend the Annual Meeting your shares will be voted as directed by you.

Can I Vote My Shares by Filling Out and Returning the Notice of Internet Availability of Proxy Materials?

No. The Notice of Availability and proxy card contain instructions on how to vote by proxy via the Internet, by telephone, by requesting and returning a paper proxy card, or by voting online while virtually attending the Annual Meeting.

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How Do I Submit a Question at the Annual Meeting?

If you wish to submit a question during the Annual Meeting, beginning at 1:15 p.m., Eastern time, on June 11, 2024, you may log into, and submit a question on, the virtual meeting platform using the unique link provided to you via email following the completion of your registration at www.proxydocs.com/KRRO, and follow the instructions there. Our virtual meeting will be governed by our Rules of Conduct and Procedures, which will be posted at www.proxydocs.com/KRRO in advance of the Annual Meeting. The Rules of Conduct and Procedures will address the ability of stockholders to ask questions during the meeting, including rules on permissible topics, and rules for how questions and comments will be recognized and disclosed to meeting participants.

May I See a List of Stockholders Entitled to Vote as of the Record Date?

A list of stockholders as of the close of business on the record date will be available for examination by the stockholders during the Annual Meeting using the unique link provided via email one hourfollowing the completion of registration for the Annual Meeting. In addition, a list of our stockholders of record will be open for examination by any stockholder beginning ten days prior to the Annual Meeting. After completionIf you would like to view the list, please contact our corporate secretary to make arrangements by calling (617) 468-1999 or writing to our corporate secretary at One Kendall Square, Building 600-700, Suite 6-401, Cambridge, MA 02139, Attention: Corporate Secretary.

Quorum

A quorum of your registrationstockholders is necessary to hold a valid meeting. Our amended and restated bylaws provide that a quorum will exist if the holders of a majority in voting power of the capital stock issued and outstanding and entitled to vote at the meeting are present at the meeting in person, or by the Registration Deadline, further instructions, including a unique link to accessremote communication, or represented by proxy. Shares that are represented virtually during the Annual Meeting will be emailedconsidered shares of common stock represented in person at the meeting for purposes of determining whether a quorum is present. If a quorum is not present, we expect to you. For any questions on how to register foradjourn the Annual Meeting please contact Jason Glashow at (781)until a quorum is obtained.

Abstentions and broker 315-4628non-votes count as present for establishing a quorum but will not be counted as votes cast. Broker non-votes occur when your bank, broker or jglashow@frequencytx.com.

Whatother nominee submits a proxy for your shares (because the bank, broker or other nominee has received instructions from you on one or more proposals, but not all proposals, or has not received instructions from you but is the purpose of the Annual Meeting?

The purpose of the Annual Meeting isentitled to vote on a particular “discretionary” matter) but does not indicate a vote for a particular proposal because the following items described in this Proxy Statement:bank, broker or other nominee either does not have the authority to vote on that proposal and has not received voting instructions from you or has discretionary authority but chooses not to exercise it.

Ballot Measures Considered “Discretionary” and “Non-Discretionary”

Votes Required to Elect a Director, to Approve the Amendment of our Restated Certificate of Incorporation and to Ratify Appointment of Ernst & Young LLP

A nominee will be elected as a director if the nominee receives a plurality of the votes cast by stockholders entitled to vote on the holder’s behalf.election (Proposal No. 1). Votes withheld and broker non-votes will not be counted as votes cast on Proposal No. 1. Accordingly, votes withheld and broker non-votes will have no effect on the voting on Proposal No. 1.

What do I do if my shares are held in “street name”?

If your shares are held in a brokerage account or by a bank or other holderThe amendment of record, you are consideredour Restated Certificate of Incorporation requires the “beneficial owner” of shares held in “street name.” The proxy materials have been forwarded to you by your broker, bank or other nominee who is considered, with respect to those shares, the stockholder of record. As the beneficial owner, you have the right to direct your broker, bank or nominee on how toaffirmative vote your shares by following their instructions for voting. Please refer to the information from your bank, broker or other nominee on how to submit your voting instructions. In addition, as discussed below, if you are a street name stockholder, you are invited to attend and vote your shares at the Annual Meeting live via webcast so long as you register to attend the Annual Meeting at www.proxydocs.com/FREQ by the Registration Deadline and have requested a legal proxy from your broker, bank, or nominee. See “How do I attend the Annual Meeting?”

How many shares must be present to hold the Annual Meeting?

A quorum must be present at the Annual Meeting for any business to be conducted. The holders of a majority in voting power of our capital stock issued and outstanding and entitled to vote, present by remote communication or represented by proxy, constitutes a quorum. If you sign and return your paper proxy card or authorize a proxy to vote electronically or telephonically, your shares will be counted to determine whether we have a quorum even if you abstain or fail to vote as indicated in the proxy materials.

Emerging Growth Company

We are not availablean “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. We will remain an emerging growth company until the earlier of (1) the last day of the fiscal year (a) following the fifth anniversary of the closing of our initial public offering, (b) in which we have total annual gross revenue of at least $1.235 billion, or (c) in which we are deemed to usbe a large accelerated filer, which means the market value of our common stock that is held by non-affiliates exceeds $700 million as of the prior June 30th, and (2) the date on which we have issued more than $1.0 billion in time to file a Form 8-Knon-convertible within four business days afterdebt during the Annual Meeting, we intend to file a Form 8-K to publish preliminary results and, within four business days after the final results are known to us, file an additional Form 8-K to publish the final results.prior three-year period.

Who should I call if I have any additional questions?

If you are the stockholder of record for your shares, please call Jason Glashow at (781) 315-4628. If your shares are held in street name, please contact the telephone number provided on your voting instruction form or contact your bank, broker or other nominee directly.7

PROPOSAL 1: NO. 1—ELECTION OF TWO CLASS II DIRECTORS

Board Size and Structure

Our Certificate of Incorporation as currently in effect (“Certificate of Incorporation”) provides that the numberboard of directors shall be established from time to time bycurrently consists of seven members. In accordance with the terms of our Boardrestated certificate of Directors. Our Board has fixed the numberincorporation, our board of directors at seven, and we currently have seven directors serving on the Board.

Our Certificate of Incorporation provides that the Board of Directors beis divided into three classes designated as Class(Class I, Class II and Class III. EachIII), with members of each class must consist, as nearly as may be possible, of one-thirdserving staggered three-year terms. The members of the total number ofclasses are divided as follows:

Upon the expiration of the term of a class of directors, directors in that class will be eligible to be elected for a new three-year term at the annual meeting of stockholders in the year in which their term expires.

Our restated certificate of incorporation, as amended, provides that the authorized number of directors may be changed only by resolution of our board of directors, subject to the rights of holders of our preferred stock. Our restated certificate of incorporation, as amended, also provides that our directors may be removed only for cause and only by the affirmative vote of the holders of at least two-thirds in voting power of the outstanding shares of our capital stock entitled to vote at an election of directors, and qualificationthat any vacancy on our board of his or her successor or until his or her earlier death, resignation or removal. In addition, contingent upon Ms. Feldmann’s electiondirectors, including newly created directorship in our board of directors, may be filled only by vote of a majority of our directors then in office, in each case subject to the Boardrights of Directors at this Annual Meeting, Ms. Feldmann will replace Mr. Barberich as chairholders of the audit committeeour preferred stock.

Our board of directors has nominated Ali Behbahani and Mr. Barberich will continue serving as a member of the audit committee.

Each person nominatedTimothy Pearson for election has agreedas Class II directors at the Annual Meeting. Proxies may not be voted for a greater number of persons than the number of nominees named in this proxy statement as only Class II is up for re-election at the Annual Meeting. Ali Behbahani and Timothy Pearson are both presently directors, and have indicated a willingness to continue to serve as directors, if elected, and management has no reason to believe that any nomineesuch nominees will be unableunavailable to serve. If however, priorelected at the Annual Meeting, each of these nominees would serve until the 2027 annual meeting of stockholders and until his successor has been duly elected and qualified, or, if sooner, until the director’s death, resignation or removal. In the event the nominees are unable or decline to serve as directors at the time of the Annual Meeting, the Board of Directors should learn that any nominee will be unable to serve for any reason, the proxies that otherwise would have been voted for this nominee will be voted for a substituteany nominee as selectedwho may be designated by the Board. Alternatively,present board of directors to fill the vacancy. Unless otherwise instructed, the proxy holders will vote the proxies at the Board of Directors’ discretion, may be voted for that fewer number of nominees as results from the inability of any nominee to serve. The Board of Directors has no reason to believe that any ofreceived by them FOR the nominees will be unable to serve.named below.

Information About Board Nominees and Continuingfor Election as Class II Directors

The following pages contain certain biographicalBiographical information for each nominee for director and each director whose term as a director will continue after the Annual Meeting,of April 17, 2024, including all positions he or she holds,

was on the board of Nevro Corp. (NYSE:NVRO) from August 2014 to March 2019, Genocea Biosciences (Nasdaq:GNCA) from February 2018 to May 2022, and Oyster Point Pharma (Nasdaq:OYST) from July 2017 to January 2023. He also serves on a number of private company boards. Dr. Behbahani holds a B.S. in biomedical engineering, electrical engineering and chemistry from Duke University, an M.B.A. from the Wharton School of the University of Pennsylvania and an M.D. from the University of Pennsylvania School of Medicine. We believe Dr. Behbahani is qualified to serve on the Board because of his extensive experience as a public company director and investor in the biotech industry.

Timothy R. Pearson. Mr. HuangPearson has served on the Board since completion of the Merger, and has served as the Chief Executive Officer of Carrick Therapeutics, a privately held oncology company, since July 2019. Mr. Pearson served as an Executive Vice President and the Chief Financial Officer of TESARO, Inc., an oncology-focused biopharmaceutical company, from 2014 until its acquisition by GlaxoSmithKline in February 2019. He served as an Executive Vice President, Chief Financial Officer and Treasurer of Catalyst Health Solutions, a publicly held pharmacy benefit management company, from 2011 until its acquisition by SXC Health Solutions in 2012. Prior to joining Catalyst Health Solutions, Mr. Pearson served as the Chief Financial Officer and Executive Vice President of MedImmune, Inc. Mr. Pearson has served on the board of directors of GlycoMimetics, Inc. (Nasdaq:GLYC) since 2014 and as its chairperson since 2019. He previously served on the board of directors of Ra Pharmaceuticals, Inc., a publicly held biopharmaceutical company until its acquisition by UCB in April 2020. Mr. Pearson is a Certified Public Accountant and holds dual B.S. degrees in business administration from the University of Delaware and in accounting from the University of Maryland, University College, as well as an M.S. degree in finance from Loyola College. We believe Mr. Pearson is qualified to serve on the Board because of his experience in the biopharmaceutical industry and his expertise in accounting and finance, strategic planning and leadership of complex organizations, and human capital management.

Our board of directors unanimously recommends voting “FOR” the election of Ali Behbahani and Timothy Pearson as Class II directors for a three-year term ending at the annual meeting of stockholders to be held in 2027.

Directors Continuing in Office

Biographical information as of April 17, 2024, including principal occupation and business experience during the last five years, for our directors continuing in office after the Annual Meeting is set forth below.

Ram Aiyar, Ph.D., M.B.A. Dr. Aiyar has served as our Chief Executive Officer and a director since completion of the Merger. Dr. Aiyar previously served as Chief Executive Officer and as a director of NeuroVive Pharmaceutical Asia,Legacy Korro since November 2020, and has served as its President since November 2021. Prior to joining Legacy Korro, Dr. Aiyar co-founded Corvidia Therapeutics, Inc. and most recently served its as Chief Financial Officer from January 2020 to November 2020 and Executive Vice President, Corporate and Business Development from February 2016 to November 2020. Prior to that, Dr. Aiyar held leadership roles in corporate development, product development, management, research, finance and strategy at BeneVir BioPharma, Inc., BioHealth Innovation, Inc., FlowMetric, Inc., Sofinnova Partners, J.P. Morgan Chase and Johnson & Johnson Pharmaceuticals (NYSE:JNJ). Dr. Aiyar is a co-founder and director of Protean Bio, Inc., a biopharmaceutical company. Mr. Huangdirector of Triveni Bio, Inc. and a past director of Avidea Technologies, Inc. Dr. Aiyar holds an MBAM.B.A. in finance and business strategy from Rice University, a M.A.INSEAD (France/Singapore), an M.S. in Chemistry from the University of Texas, Arlington,computer engineering and a B.S.Ph.D. in electrical and computer engineering from theDrexel University, of Texas, Austin.and a B.E. in electronics engineering from Mumbai University. We believe Mr. Huang’s extensive investmentDr. Aiyar is qualified to serve on the Board because of his significant operational and senior management experience in the life sciences industry qualifies him to serve on our boardbiopharmaceutical industry.

Nessan Bermingham, Ph.D. Dr. Bermingham, one of directors.

December 2021 and has served as the #1 most active biopharma investor by new deal volume four consecutive yearsInterim Chief Executive Officer of Everyone Medicines since October 2022. Previously, he co-founded and by AgFunderserved as onePresident and Chief Executive Officer of the five most active U.S. agtech investors in 2020. Mr. MarcusTriplet Therapeutics from November 2018 until July 2021. Dr. Bermingham was also a Venture Partner at Atlas Venture from February 2018 until July 2021. Dr. Bermingham also served as Interim Chief Executive Officer of Liberate Bio from October 2022 until February 2023. Prior to that role, Dr. Bermingham co-founded and served as President and Chief Executive Officer of Intellia Therapeutics (Nasdaq:NTLA) from 2014 to 2017. Dr. Bermingham currently serves on the boards of directors of Intra-Cellular Therapies, Inc., MeiraGTx Holdings plc,a number of private companies and Appliedpreviously served on the board of Xilio Therapeutics Inc., publicly traded biopharmaceutical(Nasdaq:XLO). He also previously served as the chair of the board of F-Star Therapeutics prior to its reverse merger and subsequent to its acquisition as a public company, and served on the boards of several private companies. He earned his undergraduateDr. Bermingham holds a bachelor’s degree in genetics from Queen’s University Belfast and Juris Doctor degreesa Ph.D. in molecular biology from the UniversityImperial College London, and was a Howard Hughes Associate Fellow at Baylor College of California, Los Angeles.Medicine. We believe that Mr. Marcus’ extensiveDr. Bermingham is qualified to serve on the Board because of his significant leadership and investment experience in the life sciences industry and as a chief executive officer and attorney qualifies him to serve on our boardbiotech industry.

Jean-Francois Formela, M.D., M.B.A. Dr. Formela, one of directors.

Class I Directors Whose Terms Expire at the 2023 Annual Meeting

Marc A. CohenLegacy Korro’s co-founders, has served as a member of ourthe Board since completion of the Merger, and previously served on Legacy Korro’s board of directors since November 2018. Dr. Formela is currently a partner at Atlas Venture, a life sciences-focused venture capital firm, which he joined in 1993. Dr. Formela is a co-founderand director of IFM Therapeutics, and serves as Chairman since June 2020 and Executive Chairman from September 2016 to June 2020. Since 2012, Mr. Cohen has served as the Chief Executive Officera director of Bublup,Ikena Oncology, Inc. (Nasdaq:IKNA), an online knowledge-sharing platform, as well as CoBro Ventures,a director of the following private companies: Scorpion Therapeutics, Inc., an investment management company. Mr. Cohen hasSail Bio, Inc., Triveni Bio, Inc. and Travin Bio, Inc. Dr. Formela also been Executive Chairmanpreviously served as a director of C4Intellia Therapeutics, since 2015Inc. (Nasdaq:NTLA), Spero Therapeutics (Nasdaq:SPRO) and Mana Therapeutics since 2018. Mr. Cohenseveral private companies. Dr. Formela is a member of the Mass General Brigham Innovation Advisory Board and a former trustee of the Boston Institute of Contemporary Art. Dr. Formela began his career as a physician practicing emergency medicine at Necker University Hospital in Paris. He holds an M.S. in Electrical EngineeringM.D. from Stanfordthe Paris University School of Medicine and a Bachelor’s degree in Engineering Sciencean M.B.A. from HarvardColumbia University. We believe Mr. Cohen’s extensive entrepreneurialDr. Formela’s experience as an investor and board member in the life sciences industry, qualifiesas well as his scientific and medical knowledge, provides him with the qualifications and skills to serve on our board of directors.the Board.

David L. Lucchino haspreviously served as our President and Chief Executive Officer through completion of the Merger and a member of our board of directorshas also served on the Board, each since November 2014 and was a co-founder of our companyFrequency with Dr. Robert S. Langer and Dr. Christopher R. Loose. From December 2014 until June 2016, Mr. Lucchino served as the President and Chief Executive Officer of Entrega Bio, a PureTech Health-founded biotechnology company focused on oral drug delivery technology. Prior to that, Mr. Lucchino co-foundedcofounded Semprus BioSciences, or Semprus, a biotechnology company, and served as its President and Chief Executive Officer from June 2007 to June 2012. Mr. Lucchino oversaw the development of the company’sSemprus’ lead medical product, which received FDA clearance in 2012. Semprus was acquired by Teleflex, Inc., or Teleflex, in June 2012. Prior to Semprus, Mr. Lucchino worked at the investment firm Polaris Partners. He started his biotech career by Co-Founding LaunchCyte, an investment firm where he was also a Managing Director. Mr. Lucchino is the immediate past chairman of the board of directors of MassBio, a non-profitnonprofit organization that represents over 1,500 life science firms and provides services and support for the biotechnology industry in Massachusetts. He is a member of the College of Fellows of the American Institute for Medical and Biological Engineering and was appointed by Massachusetts’ Governor Charlie Baker as a member of the Commonwealth’s Economic PlanningSTEM Advisory Council. Mr. Lucchino also servesserved as a trustee of Mt. Auburn Hospital, a Harvard Medical School facility for fifteen years, a trustee of the Multiple Myeloma Research Foundation, and a member of the Board of Advisors of Life Science Cares.NOLS (The National Outdoor Leadership School). Mr. Lucchino holds an MBA from the Massachusetts Institute of Technology’s or MIT’s, Sloan School of Management, an M.S. from the Newhouse School of Journalism at Syracuse University, and a

also spent over 13 years at Alynlam Pharmaceuticals, Inc. from April 2003 to November 2016 and remains an active member of the scientific advisory board. Dr. Meyers also serves on several scientific advisory boards, including the National Advisory Board on Innovation and Entrepreneurship through the Department of Commerce. Rachel is listed as an inventor on many patents and patent applications, and has numerous peer-reviewed publications. Dr. Meyers completed her postdoctoral training at Harvard Medical School in the field of signal transduction and received her Ph.D. at the Massachusetts Institute of Technology in the field of in vitro transcription. We believe Dr. Meyers’ extensive experience in the biotech industry and her expertise in drug discovery and development, including in RNA-based medicines, provide her with the qualifications and skills to serve on the Board.

Executive Officers Who Are Not Directors

Biographical information as of April 17, 2024 for our executive officers who are not directors is listed below.

Vineet Agarwal, M.B.A. Mr. Agarwal served as Chief Financial Officer since the Merger and previously served as Chief Financial Officer of Legacy Korro since May 2021. Prior to joining Korro Bio, Mr. Agarwal joined J.P. Morgan Chase & Co. In 2007 and advised healthcare companies on merger & acquisitions, capital raising and strategic initiatives. Mr. Agarwal served as Executive Director, Biotech Investment Banking at J.P. Morgan Chase & Co. from January 2019 until May 2021 and as Vice President, Biotech Investment Banking from January 2016 until January 2019. Mr. Agarwal previously served in numerous leadership roles at J.P. Morgan Chase & Co. across different countries. Mr. Agarwal holds an M.B.A. from the Institute of Management Technology, India, and a Bachelor’s degree in finance from Shri Ram College of Commerce, India.

Todd Chappell, M.B.A. Mr. Chappell has served as Chief Operating Officer since the Merger and previously served as Chief Operating Officer of Legacy Korro since August 2023 and previously served as Senior Vice President, Strategy and Portfolio Planning of Korro Bio from March 2021. Before joining Korro Bio, Mr. Chappell served as Chief Executive Officer of Rasio Therapeutics, Inc. from June 2019 until March 2021. Prior to this role, he served as Chief Executive Officer of Perceptive Navigation, LLC from June 2015 until May 2019. Mr. Chappell previously managed a portfolio of start-up pharmaceutical and medical device companies as an entrepreneur-in-residence at BioHealth Innovation, Inc. Prior to that, Mr. Chappell was a Vice President of Operations at Shape Pharmaceuticals, Inc., a portfolio company of HealthCare Ventures, LLC, where he oversaw all day-to-day operations for the development of a novel HDAC inhibitor for cutaneous t-cell lymphoma. Prior to this role, Mr. Chappell was an Executive Director of New Products at CombinatoRx, Inc., where he led the advancement of three programs from assay stage into human clinical studies. Mr. Chappell holds an M.B.A. from Boston University and a B.S. in biology from the University of California, Los Angeles.

Steve Colletti, Ph.D. Dr. Colletti served as Chief Scientific Officer since the Merger and previously served as Chief Scientific Officer of Legacy Korro since February 2023. Dr. Colletti most recently served as Senior Vice President of Drug Discovery Research and Development at Zymergen, Inc. from May 2021 to January 2023. Prior to this role, he served as Chief Scientific Officer of Lodo Therapeutics from March 2020 to May 2021 and as Senior Vice President, Head of Research and Development from September 2018 to March 2020. He previously held multiple leadership roles at Merck (NYSE:MRK), including in small molecule, natural products, oligonucleotide, peptide and fusion protein bioconjugate drug discovery, targeting programs in cardiovascular and respiratory disease, diabetes and obesity, immunological disorders, infectious diseases, neuroscience and oncology. Also at Merck, Dr. Colletti built and led the RNA Therapeutics Medicinal Chemistry department and was a core member of multiple development teams responsible for discovering more than a dozen preclinical candidates and advancing them to clinical development. Dr. Colletti is an inventor and author of over 130 patents and publications. Dr. Colletti holds a Ph.D. in chemistry from Boston University and a B.S. in chemistry from Loyola University, and was a National Institutes of Health postdoctoral fellow in chemistry at the Scripps Research Institute.

Shelby J. Walker, M.S., J.D. Ms. Walker has served as Senior Vice President, General Counsel and Corporate Secretary since the Merger and previously served as Senior Vice President, General Counsel and Corporate

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Secretary of Legacy Korro since May 2023. Ms. Walker most recently served as Senior Vice President and Head of Intellectual Property at CRISPR Therapeutics (Nasdaq:CRSP) from March 2018 to April 2023. She previously served as General Counsel at Ginkgo Bioworks, a synthetic biology company, from May 2016 to March 2018. Prior to this role, she served as Vice President, Associate General Counsel and Chief Intellectual Property Counsel at Dyax Corporation, and previously held intellectual property leadership roles at Novo Nordisk (NYSE:NVO) and ZymoGenetics. Ms. Walker holds a J.D. and L.L.M. in intellectual property law from the University of New Hampshire School of Law, master’s degrees in biotechnology and regulatory science from Johns Hopkins University, and a B.S. in biotechnology from Worcester Polytechnic Institute.

There is no arrangement or understanding between any of our directors or executive officers and any other person or persons pursuant to which he or she was or is to be selected as a director or executive officer.

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PROPOSAL NO. 2—APPROVAL OF AMENDMENT OF THE COMPANY’S RESTATED CERTIFICATE OF INCORPORATION

Background

The State of Delaware, which is our state of incorporation, enacted legislation in 2022 that enables Delaware companies to limit the liability of certain officers in limited circumstances under Section 102(b)(7) of the Delaware General Corporation Law, or DGCL. As amended, DGCL Section 102(b)(7) now permits exculpation for direct claims brought by stockholders for breach of an officer’s fiduciary duty of care, including class action. It does not eliminate officers’ monetary liability for breach of fiduciary duty claims brought by the corporation itself or for derivative claims brought by stockholders in the name of the corporation. Furthermore, the limitation on liability does not apply to breaches of the duty of loyalty, acts or omissions not in good faith or that involve intentional misconduct or a knowing violation of law, or any transaction in which the officer derived an improper personal benefit.

Our board of directors believes it is important to provide protection from certain liabilities and expenses that may discourage prospective or current directors from accepting or continuing membership on corporate boards and prospective or current officers from serving corporations. In the absence of such protection, qualified directors and officers might be deterred from serving as directors or officers due to exposure to personal liability and the risk that substantial expense will be incurred in defending lawsuits, regardless of merit. In particular, our board of directors since September 2016. Mr. Barberich has served ontook into account the boardnarrow class and type of directorsclaims that such officers would be exculpated from liability pursuant to amended DGCL Section 102(b)(7), the limited number of Verastem, Inc. since 2014,our officers that would be affected, and TScan Therapeutics, Inc. since 2019. Mr. Barberich previously served as a director for GI Dynamics, Inc. from 2011 to 2021, Tokai Pharmaceuticals, Inc. from 2009 to 2017, for HeartWare International, Inc. from 2008 to 2016, for Inotek Pharmaceuticals Corporation from 2016 to 2017, and for Neurovance, Inc. from 2010 to 2016. Mr. Barberich is co-founder, and served as the CEO and Chairman of Sepracor Inc. from 1984 to 2009. He holds a B.S. in Chemistry from Kings College. We believe Mr. Barberich’s extensive experience in the life sciences industry qualifies him to serve on our board of directors.

Robert S. Langer, Sc.D., has served as a member ofbenefits our board of directors since September 2016. Dr. Langer has served as a David H. Koch Institute Professor at MIT since 2005. Dr. Langer currently serves onbelieves would accrue to our company by providing exculpation in accordance with amended DGCL Section 102(b)(7), including, without limitation, the boardsability to attract and retain key officers and the potential to reduce litigation costs associated with frivolous lawsuits.

Our board of directors of Rubius Therapeutics, Inc., Moderna, Inc., or Moderna,balanced these considerations with our corporate governance guidelines and Puretech Health plc,practices and previously served on the boards of directors of Momenta Pharmaceuticals, Inc., Kala Pharmaceuticals, Inc., Fibrocell Science, Inc. and Millipore Corp. Dr. Langer holds a Sc.D. in Chemical Engineering from MIT and a B.S. in Chemical Engineering from Cornell University. We believe Dr. Langer’s pioneering academic work, extensive medical and scientific knowledge, and experience serving on public company boards of directors qualify him to serve on our board of directors.

Board Recommendation

The Board of Directors unanimously recommends a vote FOR the election of each of Cynthia L. Feldmann, Michael Huang, and Joel S. Marcus as a Class II director to hold office until the 2024 Annual Meeting and until his or her successor has been duly elected and qualified.

2.Officers. Except to the extent that the General Corporation Law of the State of Delaware prohibits the elimination or limitation of liability of officers for breaches of fiduciary duty, no officer of the Corporation shall be personally liable to the Corporation or its stockholders for monetary damages for any breach of fiduciary duty as an officer, notwithstanding any provision of law imposing such liability. No amendment to or repeal of this provision shall apply to or have any effect on the liability or alleged liability of any officer of the Corporation for or with respect to any acts or omissions of such officer occurring prior to such amendment or repeal. If the General Corporation Law of the State of Delaware is amended to permit further elimination or limitation of the personal liability of officers, then the liability of an officer of the Corporation shall be eliminated or limited to the fullest extent permitted by the General Corporation Law of the State of Delaware as so amended. For purposes of this Article SEVENTH, “officer” shall mean an individual who has been duly appointed as an officer of the Corporation and who, at the time of an act or omission as to which liability is asserted, is deemed to have consented to service of process to the registered agent of the Corporation as contemplated by 10 Del. C. § 3114(b).”

The proposed Certificate of Amendment to the Certificate of Incorporation (referred to in this Proposal No. 2 as the “Certificate of Amendment”) reflecting the foregoing Charter Amendment is attached as Appendix A to this proxy statement.

Reasons for the Proposed Charter Amendment

Our board of directors believes it is appropriate for public companies in states that allow exculpation of officers to have exculpation clauses in their certificates of incorporation. The nature of the role of directors and officers often requires them to make decisions on crucial matters. Frequently, directors and officers must make decisions in response to time-sensitive opportunities and challenges, which can create substantial risk of investigations, claims, actions, suits or proceedings seeking to impose liability on the basis of hindsight, particularly in the current litigious environment and regardless of merit. Limiting concern about personal risk would empower both directors and officers to best exercise their business judgment in furtherance of stockholder interests. We expect our peers to adopt exculpation clauses that limit the personal liability of officers in their certificates of incorporation, and failing to adopt the proposed Charter Amendment could impact our recruitment and retention of exceptional officer candidates that conclude that the potential exposure to liabilities, costs of defense and other risks of proceedings exceeds the benefits of serving as an officer of our company.

For the reasons stated above, on March 21, 2024, our board of directors determined that the proposed Charter Amendment is advisable and in the best interest of our company and our stockholders and authorized and approved the proposed Charter Amendment and directed that it be considered at the Annual MeetingMeeting. Our board of directors believes the proposed Charter Amendment would better position us to attract top officer candidates and retain our current officers and enable the officers to have an opportunityexercise their business judgment in furtherance of the interests of the stockholders without the potential for distraction posed by the risk of personal liability. Additionally, it would align the protections for our officers with those protections currently afforded to make a statementour directors.

The proposed Charter Amendment is not being proposed in response to any specific resignation, threat of resignation or refusal to serve by any officer.

Timing and be availableEffect of the Charter Amendment

If the proposed Charter Amendment is approved by our stockholders, it will become effective immediately upon the filing of the Certificate of Amendment with the Secretary of State of the State of Delaware, which we expect to respondfile promptly after the Annual Meeting. Other than the replacement of the existing Article Seventh by the proposed Article Seventh, the remainder of the Certificate of Incorporation will remain unchanged after effectiveness of the Charter Amendment. If the proposed Charter Amendment is not approved by our stockholders, the Certificate of Incorporation will remain unchanged. In accordance with the DGCL, our board of directors may elect to appropriate questions from stockholders.abandon the proposed Charter Amendment without further action by the stockholders at any time prior to the effectiveness of

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the filing of the Certificate of Amendment with the Secretary of State of the State of Delaware, notwithstanding stockholder approval of the proposed Charter Amendment.

Our board of directors unanimously recommends voting “FOR” Proposal No. 2 to approve the amendment of our Restated Certificate of Incorporation to limit the liability of certain officers as permitted by amendments to Delaware law.

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Independent Registered Public Accounting Firm FeesPROPOSAL NO. 3—RATIFICATION OF THE APPOINTMENT OF ERNST & YOUNG LLP AS OUR INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR THE FISCAL YEAR ENDING DECEMBER 31, 2024

The following is a summary and description of fees incurred by RSM forOur stockholders are being asked to ratify the fiscal years ended December 31, 2020 and 2019:

Pre-Approval Policy

The formal written charter for our audit committee requires that the audit committee pre-approve all audit services to be provided to us, whether provided by our principal auditor or other firms, and all other services

During our 2023 and 2022 fiscal years, no services were provided to us by Ernst & Young LLP other than in accordance with the SECpre-approval policies and procedures described above.

Our board of directors unanimously recommends voting “FOR” Proposal No. 3 to ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2024.

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CORPORATE GOVERNANCE

Director Nomination Process

Our nominating and corporate governance committee is notresponsible for identifying individuals qualified to serve as directors, consistent with criteria approved by our board, and recommending the persons to be incorporatednominated for election as directors, except where we are legally required by reference into any filingcontract, law or otherwise to provide third parties with the right to nominate director candidates.

The process followed by our nominating and corporate governance committee to identify and evaluate director candidates includes requests to board members and others for recommendations, meetings from time to time to evaluate biographical information and background material relating to potential candidates and interviews of selected candidates by members of the Companycommittee and our board. While there are no specific minimum qualifications for a committee-recommended nominee to our board of directors, the qualifications, qualities and skills that our nominating and corporate governance committee believes must be met by a committee- recommended nominee for a position on our board of directors are as follows:

An understanding of the fiduciary responsibilities required of a director and a commitment to devote the time and energy necessary to perform those responsibilities.

The nominating and corporate governance committee may use a third-party search firm in those situations where particular qualifications are required or where existing contacts are not sufficient to identify an appropriate candidate.

Stockholders may recommend individuals to the nominating and corporate governance committee for consideration as potential director candidates. Any such proposals should be submitted to our corporate secretary at our principal executive offices and should include appropriate biographical and background material to allow the nominating and corporate governance committee to properly evaluate the potential director candidate and the number of shares of our stock beneficially owned by the stockholder proposing the candidate. The specific requirements for the information that is required to be provided for such recommendations to be considered are specified in our amended and restated bylaws and must be received by us no later than the date referenced below under the Securities Actheading “Stockholder Proposals for our 2025 Annual Meeting.”

Assuming that biographical and background material has been provided on a timely basis, any recommendations received from stockholders will be evaluated in the same manner as potential nominees proposed by the nominating and corporate governance committee. If our board of 1933directors decides to nominate a stockholder- recommended candidate and recommends his or her election, then his or her name will be included on our proxy card for the next annual meeting.

Director Independence

Applicable Nasdaq rules require a majority of a listed company’s board of directors to be comprised of independent directors within one year of listing. In addition, Nasdaq rules require that, subject to specified exceptions, each member of a listed company’s audit, compensation and nominating and corporate governance

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committees be independent. Audit committee members must also satisfy the independence criteria set forth in Rule 10A-3 under the Securities Exchange Act of 1934, both as amended,

The or the Exchange Act, and compensation committee members must also satisfy the independence criteria set forth in Rule 10C-1 under the Exchange Act. Under applicable Nasdaq rules, a director will only qualify as an “independent director” if, among other things, in the opinion of the listed company’s board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director. In order to be considered independent for purposes of Rule 10A-3, a member of an audit committee operates pursuant toof a charter which is reviewed annually by the audit committee. Additionally,listed company may not, other than in his or her capacity as a brief description of the primary responsibilitiesmember of the audit committee, is included in this Proxy Statement under the discussionboard of “Corporate Governance—Audit Committee.” Underdirectors, or any other board committee, accept, directly or indirectly, any consulting, advisory, or other compensatory fee from the audit committee charter, management is responsible for the preparation, presentation and integritylisted company or any of its subsidiaries or otherwise be an affiliated person of the Company’s financial statements, the application of accounting and financial reporting principles and our internal controls and procedures designed to assure compliance with accounting standards and applicable laws and regulations. The independent registered public accounting firm is responsible for auditing our financial statements and expressing an opinion as to their conformity with accounting principles generally accepted in the United States.

In the performancelisted company or any of its oversight function,subsidiaries. In order to be considered independent for purposes of Rule 10C-1, the auditboard must consider, for each member of a compensation committee reviewed and discussed withof a listed company, all factors specifically relevant to determining whether a director has a relationship to such company which is material to that director’s ability to be independent from management and RSM US LLP, as the Company’s independent registered public accounting firm, the Company’s audited financial statements for the fiscal year ended December 31, 2020. The audit committee also discussedin connection with the Company’s independent registered public accounting firm the matters required to be discussed by applicable standards of the Public Company Accounting Oversight Board (the “PCAOB”) and the Securities and Exchange

The audit committee consists of Timothy Pearson, Nessan Bermingham and Jean-Francois Formela. Our audit committee met six times during 2023. Timothy Pearson is the chair of the audit committee and is a financial expert under the rules of the SEC. To qualify as independent to serve on our audit committee, listing standards of Nasdaq and the applicable SEC rules require that a director not accept any consulting, advisory or other compensatory fee from us, other than for service as a director, or be an affiliated person of us. We believe that the composition of the audit committee complies with the applicable requirements of the rules and regulations of Nasdaq and the SEC.

Compensation Committee

Our compensation committee will oversee policies relating to compensation and benefits of our officers and employees. Among other matters, the compensation committee’s responsibilities include:

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The compensation committee consists of Nessan Bermingham, Ali Behbahani and Timothy Pearson. Nessan Bermingham is the chair of the compensation committee. Our compensation committee met three times during 2023. Each member of our compensation committee is a “non-employee” director within the meaning of Rule 16b-3 of the rules promulgated under the Exchange Act and independent within the meaning of the independent director guidelines of Nasdaq. We believe that the composition of the compensation committee complies with the applicable requirements of the rules and regulations of Nasdaq.

Nominating and Corporate Governance Committee

The nominating and corporate governance responsibilities include:

The nominating and corporate governance committee consists of Ali Behbahani, Jean-Francois Formela and Rachel Meyers. Our nominating and corporate governance committee did not meet in 2023. Ali Behbahani is the chair of the nominating and corporate governance committee. We believe that the composition of the nominating and corporate governance committee meets the requirements for independence under, and the functioning of such nominating and corporate governance committee complies with, any applicable requirements of the rules and regulations of Nasdaq.

Board Diversity

We believe that it is important that our board of directors reflects the diversity of employees and the communities that we serve. Diversity is a factor that our nominating and corporate governance committee considers when identifying nominees to serve as directors. As required by rules of the Nasdaq Stock Market, we are providing information about the gender and demographic diversity of our directors in the format required by Nasdaq rules.

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The information in the matrix below is based solely on information provided by our directors about their gender and demographic self-identification as of     , 2024. Directors who indicated that they preferred not to answer a question are shown as “did not disclose gender” or “did not disclose demographic background” below.

Board of Director Meetings and Attendance

Our board of directors recognizes the importance of director attendance at board and committee meetings. The full board of directors met 16 times during 2023. During 2023, each member of the board of directors attended in person or participated in 75% or more of the aggregate of (i) the total number of meetings held by the board of directors (during the period that such person served as a director) and (ii) the total number of meetings held by all committees of the board of directors on which such person served (during the periods that such person served).

Director Attendance at Annual Meeting of Stockholders

Our corporate governance guidelines provide that directors are responsible for attending the annual meeting of stockholders.

Code of Business Conduct and Ethics;Ethics

discussingCompensation Recovery Policy

In accordance with the requirements of the SEC and Nasdaq listing rules, our board of directors adopted a compensation recovery policy on November 3, 2023, effective as of October 2, 2023. The compensation recovery policy provides that in the event we are required to prepare a restatement of financial statements due to material noncompliance with any financial reporting requirement under securities laws, we will seek to recover any incentive-based compensation that was based upon the attainment of a financial reporting measure and that was received by any current or former executive officer during the three-year period preceding the date that the restatement was required if such compensation exceeds the amount that the executive officers would have received based on the restated financial statements..

Board Leadership Structure and Oversight of Risk

We currently separate the roles of chief executive officer and chairman of the board of directors. Our president and chief executive officer is responsible for setting the strategic direction for our company and the day-to-day leadership and performance of our company, while the chairman of our board of directors presides over meetings of the board of directors, including executive sessions of the board of directors, and performs oversight responsibilities. Separating the duties of the chair from the duties of the chief executive officer allows our chief executive officer to focus on our day-to-day business, while allowing the chair to lead the board of directors in its fundamental role of providing advice to and independent oversight of management. Specifically, our chair runs meetings of our independent directors, facilitates communications between management and the board of directors and assists with other corporate governance matters. Our board of directors believes that this structure ensures a greater role for the independent directors in the oversight of our company and active participation of the independent directors in setting agendas and establishing priorities and procedures for the work of our board of directors. Our board of directors believes its administration of its risk oversight function has not affected its leadership structure. Our board of directors believes that we have an appropriate leadership structure for us at this time which demonstrates our commitment to good corporate governance. Although the roles of chair and chief executive officer are currently separate, our nominating and corporate governance committee and board of directors believe it is appropriate for our chief executive officer to serve as a member of our board of directors.

Risk is inherent with every business and how well a business manages risk can ultimately determine its success. We face a number of risks, including those described under “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2023. Our board of directors is actively involved in oversight of risks that could affect us. Our board of directors oversees our risk management policies;

establishingin any other hedging transaction with respect to our securities. Our insider trading policy also expressly prohibits such persons from borrowing against our securities held in a margin account, or pledging our securities as collateral for a loan.

Communication with Our Directors

Any interested party with concerns about our company may report such concerns to the board of directors, or the chairman of our board of directors, or otherwise the chair of the nominating and corporate governance committee, by submitting a written communication to the attention of such director at the following address:

Korro Bio, Inc.

One Kendall Square, Building 600-700, Suite 6-401

Cambridge, Massachusetts 02139

Attention: Board of Directors

You may submit your concern anonymously or confidentially by postal mail. You may also indicate whether you are a stockholder, customer, supplier, or other interested party.

A copy of any such written communication may also be forwarded to our legal counsel and a copy of such communication may be retained for a reasonable period of time. The director may discuss the matter with our legal counsel, with independent advisors, with non-management directors, or with our management, or may take other action or no action as the director determines in good faith, using reasonable judgment, and discretion.

Communications may be forwarded to all directors if they relate to important substantive matters and include suggestions or comments that may be important for the directors to know. In general, communications relating to corporate governance and long-term corporate strategy are more likely to be forwarded than communications relating to ordinary business affairs, personal grievances, and matters as to which we tend to receive repetitive or duplicative communications.

The audit committee oversees the procedures for the receipt, retention, and treatment of complaints received by us regarding accounting, internal accounting controls, or auditingaudit matters, and for the confidential, and anonymous submission by our employees of concerns regarding questionable accounting, internal accounting controls or auditing matters. Concerns regarding questionable accounting or auditing matters and, more generally, suspected violations ofor complaints regarding accounting, internal accounting controls or auditing matters may be submitted in writing online at https://www.whistleblowerservices.com/korrobio or to our Code of Business Conduct and Ethics; and

EXECUTIVE OFFICER AND DIRECTOR COMPENSATION

On November 3, 2023, Frequency completed the Merger with Legacy Korro. At the effective time of the Merger, the management of Frequency was replaced with the management of Legacy Korro. Unless otherwise indicated, the disclosures in this section regarding Frequency’s common stock or securities convertible into common stock for periods or as of a date that precedes the closing of the Merger have been adjusted to give effect to the Reverse Stock Split, and the disclosures in this section regarding Legacy Korro’s common stock or securities convertible into Legacy Korro’s common stock for periods or as of a date that precedes the closing of the Merger have been adjusted to give effect to the Exchange Ratio and the Reverse Stock Split.

This discussion may contain forward-looking statements that are based on our current plans, considerations, expectations and determinations regarding future compensation programs. Actual compensation programs that we adopt in the future could vary significantly from our historical practices and currently planned programs summarized in this discussion.

Executive Compensation Overview

This section discusses the material components of the executive compensation program for our named executive officers, which consists of (i) any person who areserved as our principal executive officer during any part of 2023, (ii) our two most highly compensated executive officers (other than our principal executive officers) who were serving as executive officers on December 31, 2023, and (iii) one additional individual who would have been under clause (ii) but for the fact that he was not serving as an executive officer on December 31, 2023. In 2023, our named in the 2020 Summary Compensation Table below. In 2020,executive officers were:

2020

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2023 Summary Compensation Table

The following table presents information regarding the total compensation tableawarded to, earned by and paid to our named executive officers for services during 2023.

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Narrative Disclosure to summarythe 2023 Summary Compensation Table

Prior to the Merger, our compensation table

Ourcommittee reviewed compensation annually for all employees, including our executive officers. Following the Merger, our compensation program is designed to align compensation with business objectives and the creation of stockholder value, while also enabling us to attract, motivate and retain individuals who contribute to our long-term success. For 2020,committee anticipates annually reviewing the compensation of our namedemployees, including our executive officers. In setting executive base salaries and bonuses and granting equity incentive awards, the compensation committee considers compensation for comparable positions in the market, the historical compensation levels of our executive officers, individual performance as compared to our expectations and objectives, internal equity, our desire to motivate our employees to achieve short- and long-term results that are in the best interests of our stockholders, and a long-term commitment to us. We target a general competitive position and consider independent third-party benchmark analytics to determine the mix of compensation of base salary, bonus and long-term incentives.

Our compensation committee is primarily consistedresponsible for determining the compensation for our executive officers. Our compensation committee typically reviews and discusses management’s proposed compensation with our Chief Executive Officer for all executives other than the Chief Executive Officer. Based on those discussions and its discretion, taking into account the factors noted above, the compensation committee then sets the compensation for each executive officer other than the Chief Executive Officer. For the Chief Executive Officer, our compensation committee determines and approves the compensation, or upon request of the board of directors, recommends our Chief Executive Officer’s compensation for approval by our board of directors. Our compensation committee may delegate certain authorities to an officer of our company and has delegated to our Chief Executive Officer the authority to make certain equity award grants to employees (other than our executive officers), within specified limits approved by the compensation committee. Our compensation committee has the authority to engage the services of a base salary, an annual cash incentive bonus opportunity, equityconsulting firm or other outside advisor to assist it in designing our executive compensation programs and in making compensation decisions. During 2023, the formcompensation committee retained the services of stock optionsAlpine Rewards LLC, or Alpine, as its external compensation consultant to advise on executive compensation matters including our overall compensation program design and health and welfare benefits. Pursuantcollection of market data to their employment agreements, the namedinform our compensation programs for our executive officers are also eligibleand members of our board of directors. Alpine reports directly to receive certain paymentsour compensation committee. Our compensation committee annually assesses its independence consistent with Nasdaq listing standards and benefits upon a terminationconcluded that the engagement of employment under certain circumstances.such consultant did not raise any conflict of interest.

2020 salaries2023 Base Salaries

Each of the named executive officers receives aofficers’ base salary to provideis a fixed component of annual compensation intendedfor performing specific duties and functions. Base salaries are adjusted from time to reflecttime to realign salaries with market levels after taking into account individual responsibilities, performance and experience. For the executive’s skill set, experience, role and responsibilities. Annualfiscal year ended December 31, 2023, the annual base salaries are

2020 bonuses2023 Annual Bonuses

We offer our named executive officersDuring the opportunityyear ended December 31, 2023, Dr. Aiyar, Mr. Lucchino (prior to termination of his employment), Mr. Agarwal, Dr. Colletti, and Dr. Loose (prior to termination of his employment), were each eligible to earn annual performance bonuses to compensate them for attaining short-term company and individual goals established by our board of directors. Each named executive officer has an established target annual performance bonus amount, expressed as a percentage of the named executive officer’s annual base salary. The target bonus amounts for Mr. Lucchino, Mr. Pfreundschuh and Ms. Arnold in 2020 were 55%, 40% and 35%, respectively.

In January 2021, the compensation committee evaluated the named executive officers’ performance against the relevant bonus goals and approved the amounts earned by our named executive officers under the Company’s annual bonus program for 2020 and included above in the 2020 Summary Compensation Table. The amounts earned for Mr. Lucchino and Ms. Arnold exceeded their target bonus based on their individual performance and/or our performance as a company. For the exceptional performance of our Company and of each of them individually in 2020, as determined byyear ended December 31, 2023, the compensation committee. Specifically, the compensation committee considered our Company’s completed enrollment of our Phase 2a study in the midst of the Covid-19 pandemic, initiation of two clinical trialstarget annual bonuses for patients living with age-related and severe hearing loss, completion of a durability study, continued advancement of our next generation work on hearing, advancement of our multiple sclerosis program, advancement of our pre-commercial related studies, and the expansion of our team in critical areas, preparing Frequency for its next phase of growth. As a result, the actual bonuses awarded toDr. Aiyar, Mr. Lucchino (prior to termination of his employment), Mr. Agarwal, Dr. Colletti, and Ms. Arnold for 2020 performanceDr. Loose (prior to termination of his employment) were approved at above target. The amount earned for Mr. Pfreundschuh matched his target bonusequal to 45%, 60%, 35%, 35%, and was pro-rated to reflect the portion40%, respectively, of the calendar year during which he was employed.their applicable annual base salaries.

Equity compensationIncentive Compensation

Although we do not haveneither Legacy Korro nor Frequency had a formal policy with respect to the grant of equity incentive awards to ourits executive officers, including our named executive officers, or any formal equity ownership guidelines applicable to them, we believe that equity grantsawards provide our executive officers with a strong link to our long-term performance, create an ownership culture and help to align the interests of our executive officersexecutives and our stockholders. In addition, we believe that equity grantsawards with a time-based vesting feature promote executive retention because this feature incentivizes our executive officers to remain in our employment during the applicable vesting period. Accordingly, our board of directors periodically reviews the equity incentive compensation of our executives, including our named executive officers and from time to time may grant equity incentive awards to them in the form of stock options.

We typically grant stock option awards to each executive officer and employee upon the individual’s commencement of employment and make additional grants of stock option awards on an annual basis for retention purposes. Each option has an exercise price equal to the fair market value of our common stock on the date of grant. During the fiscal year ended December 31, 2020,them. In 2023, we granted stock options and RSUs to each of our named executive officers, as showndescribed in more detail in the “Outstanding“—Outstanding Equity Awards at Fiscal Year End”2023 Year-End” table below.

Other elements of compensationPerquisites

We generally do not provide perquisites to our employees, other than certain de minimis perquisites available to all of our employees, including our named executive officers. However, pursuant to his employment agreement with us, Dr. Colletti is also entitled to reimbursement (i) for reasonable expenses incurred in connection with travel to work at our offices and (ii) up to $4,000 per month for housing in the greater Boston, Massachusetts area.

Retirement plan401(k) Plan

We maintain the Korro Bio 401K Retirement Plan, a tax-qualified retirement plan that provides eligible employees, including the named executive officers, with an opportunity to save for retirement on a tax-advantaged basis. Plan participants are able to defer eligible compensation subject to applicable annual limits under the Code. Participants’ pre-tax or Roth contributions are allocated to each participant’s individual account and are then invested in selected investment alternatives according to the participants’ directions. Participants are immediately and fully vested in their contributions. We match each participant’s contribution up to a maximum of 3% of his or her eligible compensation with participants vesting immediately and fully in such matching contributions. Our 401(k) plan is intended to be qualified under Section 401(a) of the Code with the 401(k) plan’s related trust intended to be tax exempt under Section 501(a) of the Code.

Prior to the consummation of the Merger, Frequency maintained a 401(k) retirement savings plan, for our employees, or the Frequency 401(k) Plan, including our named executive officers, who satisfy certain eligibility requirements. Our named executive officers arefor Frequency employees. Prior to their respective terminations, Mr. Lucchino and Dr. Loose were eligible to participate in the Frequency 401(k) Plan on the same terms as other full-time Frequency employees. Under this plan, during 2020 we

Ram Aiyar

On October 13, 2020, Legacy Korro entered into an offer letter with our compensation policies.

HealthDr. Aiyar, or the Aiyar Offer Letter. The Aiyar Offer Letter sets forth his initial annual base salary of $450,000, initial target bonus opportunity equal to 40% of Dr. Aiyar’s annual base salary, initial equity grant, and welfare plans

During their employment, our named executive officers are eligiblehis eligibility to participate in our employee benefit plans generally.

The Aiyar Offer Letter provided that in the event that Dr. Aiyar’s employment was terminated by Legacy Korro without “cause” or by him for “good reason” (as such terms are defined in the Aiyar Offer Letter), in either case within three months before or 12 months following a change in control, or the Aiyar Change in Control Period, subject to Dr. Aiyar’s signing and programs, including medical, dentalcomplying with a separation agreement and vision benefits,release, Dr. Aiyar would be entitled to the same extent as our other full-time employees,following severance benefits: (i) a lump sum cash payment equal to sum of (x) 12 months of his then-current base salary (or the base salary in effect immediately prior to the change in control, if higher), plus (y) 100% of Dr. Aiyar’s target annual bonus for the year of termination, without regard to whether the metrics had been established or achieved for such year; (ii) if Dr. Aiyar elected COBRA health continuation, a monthly payment to the group health plan provider or the COBRA provider for up to 12 months, and (iii) 100% of all equity awards held by Dr. Aiyar would have immediately accelerated in vesting and become fully exercisable or non-forfeitable.

In addition, in the event that Dr. Aiyar’s employment were terminated by Legacy Korro without “cause” or by him for “good reason”, in either case outside the Aiyar Change in Control Period, subject to Dr. Aiyar’s signing and complying with a separation agreement and release, Dr. Aiyar would have been entitled to the terms and eligibility requirementsseverance benefits as described in the preceding paragraph, payable in substantially equal installments over a 12-month period, provided that Dr. Aiyar would not have been entitled to any acceleration of those plans.

Outstandingvesting of his equity awards at 2020 fiscal year-end

Mr. Lucchino was also party to restrictive covenant agreements, pursuant to which he agreed to refrain from competing with us or soliciting its customers or employees during his employment and vest asfor one year following termination of his employment and from disclosing our proprietary information during or at any time following his employment.

Vineet Agarwal

On March 12, 2021, Legacy Korro entered into an employment agreement with Mr. Agarwal, or the Prior Agarwal Employment Agreement. The Prior Agarwal Employment Agreement set forth his initial annual base salary of $385,000, initial target bonus opportunity equal to 35% of Mr. Agarwal’s base salary, initial equity grant, and his eligibility to participate in our employee benefit plans generally.

The Prior Agarwal Employment Agreement provided that in the event that Mr. Agarwal’s employment were terminated by Legacy Korro without “cause” or by him for “good reason” (as such terms are defined in the Prior Agarwal Employment Agreement), in either case within 12 months following a change in control, or the Agarwal Change in Control Period, subject to Mr. Agarwal’s signing and complying with a separation agreement and release, Mr. Agarwal would have been entitled to the numberfollowing severance benefits: (i) a lump sum cash payment equal to sum of shares that(x) nine months of his then-current base salary (or the base salary in effect immediately prior to the change in control, if higher), plus (y) 100% of Mr. Agarwal’s target annual bonus for the year of termination, without regard to whether the metrics had been established or achieved for such year; (ii) if Mr. Agarwal elected COBRA health continuation, a monthly payment to the group health plan provider or the COBRA provider for up to nine months, and (iii) 100% of all equity awards subject to time-based vesting held by Mr. Agarwal would have vestedimmediately accelerated in vesting and become fully exercisable or non-forfeitable.

In addition, in the event that Mr. Agarwal’s employment were terminated by Legacy Korro without “cause” or by him for “good reason”, in each case outside the Agarwal Change in Control Period, subject to Mr. Agarwal’s signing and complying with a separation agreement and release, Mr. Agarwal would have been entitled to the severance benefits as described in the preceding paragraph, payable in substantially equal installments over a nine-month period, provided that Mr. Agarwal would not have been entitled to any acceleration of vesting of his equity awards and the target annual bonus described above would have been prorated based on the date of termination.

Steven Colletti

On January 20, 2023, Legacy Korro entered into an employment agreement with Dr. Colletti, or the Prior Colletti Employment Agreement. The Prior Colletti Employment Agreement set forth his initial annual base salary of $420,000, initial target bonus opportunity equal to 35% of Dr. Colletti’s base salary, initial equity grant, and his eligibility to participate in our employee benefit plans generally.

The Prior Colletti Employment Agreement provided that in the event that Dr. Colletti’s employment were terminated by Legacy Korro without “cause” or by him for “good reason” (as such terms are defined in the Prior Colletti Employment Agreement), in either case within 12 months following a change in control, or the Colletti Change in Control Period, subject to Dr. Colletti’s signing and complying with a separation agreement and release, Dr. Colletti would have been entitled to the following severance benefits: (i) a lump sum cash payment equal to sum of (x) nine months of his then-current base salary (or the base salary in effect immediately prior to the change in control, if higher), plus (y) 100% of Dr. Colletti’s target annual bonus for the year of termination, without regard to whether the metrics had he remainedbeen established or achieved for such year; (ii) if Dr. Colletti elected COBRA health continuation, a monthly payment to the group health plan provider or the COBRA provider for up to nine months, and (iii) 100% of all equity awards subject to time-based vesting held by Dr. Colletti would have immediately accelerated in vesting and become fully exercisable or non-forfeitable.

In addition, in the event that Dr. Colletti’s employment were terminated by Legacy Korro without “cause” or by him for “good reason”, in each case outside the Colletti Change in Control Period, subject to Dr. Colletti’s

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signing and complying with a separation agreement and release, Dr. Colletti would have been entitled to the severance benefits as described in the preceding paragraph, payable in substantially equal installments over a nine-month period, provided that Dr. Colletti would not have been entitled to any acceleration of vesting of his equity awards and the target annual bonus described above would have been prorated based on the date of termination.

Christopher R. Loose

Frequency entered into an amended and restated employment agreement with Dr. Loose on September 20, 2019, pursuant to which Frequency employed Dr. Loose as its Chief Scientific Officer. Dr. Loose’s employment agreement had an indefinite term.

Dr. Loose’s employment agreement provided for an additional six months followingannual base salary of $425,000, which was increased to $480,344 effective January 1, 2022, and a target annual performance bonus equal to 40% of his datebase salary, and was based on the attainment of termination. Ifpredetermined individual and company performance objectives agreed upon between Dr. Loose and Frequency.

In the event Frequency terminated Dr. Loose’s employment without “cause” or he resigned for “good reason” (as such a qualifying termination occurs following a “changeterms are defined in control”his employment agreement), subject to his execution and non-revocation of a release Mr. Lucchino will bein our favor, he was entitled to receive the samefollowing termination payments exceptpayments: (i) the severance payment will be equal to eighteen12 months’ continued base salary in equal installments following his termination, (ii) 100% of his target annual bonus paid in a lump sum within 14 days following his execution of the release and (ii) all(iii) if he made an election, up to twelve months continued coverage under COBRA, with us paying the same portion of the COBRA premiums as we pays for active employees. If such a qualifying termination occurs within twelve months following a “change in control” (as defined in his employment agreement), Dr. Loose’s equity awards held by Mr. Lucchino will acceleratewould have accelerated and vest (including performance vesting awards, which will vest at target level of achievement).vested.

Mr. Lucchino is alsoDr. Loose was a party to restrictive covenant agreements, pursuant to which he has agreed to refrain from competing with us or soliciting our customers or employees during his employment and for one year following termination of his employment and from disclosing our proprietary information during or at any time following his employment.

Mr. PfreundschuhOn July 28, 2023, Frequency entered into a separation agreement with Dr. Loose pursuant to which, in exchange for a general release of claims in our favor, he was entitled to receive (i) continued payment of his base salary for a period of 12 months from July 28, 2023, (ii) continued group health plan coverage under COBRA for up to 12 months, with Frequency paying the portion of the premium that it would pay for active and similarly situated employees, (iii) $201,744.35, which was equal to 100% of his 2023 target bonus opportunity, and (iv) accelerated vesting of all of his unvested stock options and RSUs, subject to the closing of the Merger prior to or on December 31, 2023.

Current Offer Letters and Employment Agreements

We entered new employment agreements with certain of our executive officers following the closing of the Merger, the terms of which are described below.

Ram Aiyar

On November 10, 2023, we entered into ana new employment agreement with Mr. Pfreundschuh on November 24, 2020, pursuant to which we employ Mr. Pfreundschuh asDr. Ram Aiyar, our President and Chief Financial Officer. The employment agreementExecutive Officer, or the Aiyar Employment Agreement. Under the Aiyar Employment Agreement, Dr. Aiyar has an indefinite term.

The employment agreement for Mr. Pfreundschuh provides for aninitial annual base salary of $450,000, a$498,487 and an initial target annual performance bonus opportunity equal to 40%45% of his annual base salary, based on the attainment of predetermined individualhe continues to remain eligible for equity grants under our equity incentive plans, and company performance objectives determined byhe continues to be eligible to participate in our board of directors, and a relocation bonus equal to $70,000, which was payable on the first payroll date following the commencement of his employment.employee benefit plans generally.

In

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The Aiyar Employment Agreement provides that in the event we terminate Mr. Pfreundschuh’s employmentDr. Aiyar is terminated without “cause” or he resigns for “good reason” (as such terms are defined therein) outside of the change in the employment agreement)control period (which extends from three months prior to a change in control to 12 months following a change in control, as “change in control” is defined therein), subject to his executionsigning and non-revocation ofcomplying with a separation agreement and release, which shall include, without limitation, a release in

following severance benefits: (i) nine months of his then-current base salary, (ii) a pro rata target bonus for the year of termination, without regard to whether the metrics have been established or achieved for such year, and (iii) subject to his copayment of premium amounts at the applicable active employees’ rate and proper election to continue COBRA health coverage, up to nine months of payment of the portion of the premium equal to the amount we would have paid to provide health insurance had he remained employed by us.

The Agarwal Employment Agreement provides enhanced severance pay and benefits in the event Mr. Agarwal’s employment is terminated by us without cause or Mr. Agarwal resigns for good reason, in each case, within the change in control period. Such enhanced severance pay and benefits consist of (i) a lump sum cash payment equal to the sum of (A) 12 months of Mr. Agarwal’s then-current base salary (or the base salary in effect immediately prior to the change in control, if higher) plus (B) 1.0 times Mr. Agarwal’s target annual bonus for the then current year, without regard to whether the metrics have been established or achieved for such year, (ii) subject to his copayment of premium amounts at the applicable active employees’ rate and proper election to continue COBRA health coverage, up to 12 months of payment of the portion of the premium equal to the amount we would have paid to provide health insurance had he remained employed by us, and (iii) accelerated vesting of the then-outstanding and unvested portion of Mr. Agarwal’s stock options and other stock-based awards that are subject solely to time-based vesting. The severance pay and benefits described in this paragraph are subject to Mr. Agarwal’s delivery of and compliance with a fully effective release of claims.

The payments and benefits under the Agarwal Employment Agreement in connection with a change in control may not be eligible for federal income tax deduction by us pursuant to Section 280G of Code. These payments and benefits may also be subject to an excise tax under Section 4999 of the Code. If the payments or benefits payable to Mr. Agarwal in connection with a change in control would be subject to the excise tax imposed under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after-tax benefit to him.

Mr. Agarwal entered into an Employee Proprietary Information and Inventions Assignment Agreement that contains, among other provisions, nondisclosure of confidential information, invention assignment and nonsolicitation provisions.

Steven Colletti

On November 8, 2023, we entered into a new employment agreement with Steven Colletti, our Chief Scientific Officer, or the Colletti Employment Agreement. Under Dr. Colletti’s new employment agreement, he has an initial annual base salary of $420,000, an initial target bonus opportunity equal to 35% of his annual base salary (with any incentive bonus for 2023 to be prorated based on Dr. Colletti’s days of employment with our company during 2023) and continues to remain eligible for equity grants under our equity incentive plans, and continues to be eligible to participate in our employee benefit plans generally.

The Colletti Employment Agreement provides that in the event Dr. Colletti is terminated without “cause” or he resigns for “good reason” (as such terms are defined therein) outside of the change in hercontrol period (which extends from three months prior to a change in control to 12 months following a change in control, as “change in control” is defined therein), subject to signing and complying with a separation agreement and release, which shall include, without limitation, a release of claims, a reaffirmation of restrictive covenants, and in our sole discretion, a one year post-employment noncompetition agreement, then Dr. Colletti will be entitled to the following severance benefits: (i) nine months of his then-current base salary, plus (ii) a pro rata target bonus for the year of termination, without regard to whether the metrics have been established or achieved for such year, and (iii) subject to his copayment of premium amounts at the applicable active employees’ rate and proper election to continue COBRA health coverage, up to nine months of payment of the portion of the premium equal to the amount we would have paid to provide health insurance had he remained employed by us.

The Colletti Employment Agreement provides enhanced severance pay and benefits in the event Dr. Colletti’s employment agreement), Ms. Arnold’sis terminated by us without cause or Dr. Colletti resigns for good reason, in each case, within the

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change in control period. Such enhanced severance pay and benefits consist of (i) a lump sum cash payment equal to the sum of (A) 12 months of Dr. Colletti’s then-current base salary (or the base salary in effect immediately prior to the change in control, if higher) plus (B) 1.0 times Dr. Colletti’s target annual bonus for the then-current year, without regard to whether the metrics have been established or achieved for such year, (ii) subject to his copayment of premium amounts at the applicable active employees’ rate and proper election to continue COBRA health coverage, up to 12 months of payment of the portion of the premium equal to the amount we would have paid to provide health insurance had he remained employed by us, and (iii) accelerated vesting of the then-outstanding and unvested portion of Dr. Colletti’s stock options and other stock-based awards that are subject solely to time-based vesting. The severance pay and benefits described in this paragraph are subject to Dr. Colletti’s delivery of and compliance with a fully effective release of claims.

The payments and benefits under the Colletti Employment Agreement in connection with a change in control may not be eligible for federal income tax deduction by us pursuant to Section 280G of the Code. These payments and benefits may also be subject to an excise tax under Section 4999 of the Code. If the payments or benefits payable to Dr. Colletti in connection with a change in control would be subject to the excise tax imposed under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after-tax benefit to him.

Dr. Colletti entered into an Employee Proprietary Information and Inventions Assignment Agreement that contains, among other provisions, nondisclosure of confidential information, invention assignment and nonsolicitation provisions.

Outstanding Equity Awards at 2023 Fiscal Year-End

The following table sets forth information concerning outstanding equity awards will accelerateheld by each of the named executive officers as of December 31, 2023. For Messrs. Aiyar, Agarwal and vest.Colletti, each equity award granted prior to the Merger were under the terms of the Legacy Korro Plan and each equity award granted following the Merger were under the terms of our 2023 Stock Option and Incentive Plan, or the 2023 Plan. For Mr. Lucchino and Dr. Loose, each equity award granted prior to the Merger were under the terms of Frequency’s 2019

Ms. Arnold is party

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Incentive Award Plan, or the 2019 Plan or Frequency’s the 2014 Stock Incentive Plan, as amended, or the 2014 Plan, and each equity award granted following the Merger were under the terms of the 2023 Plan.

Non-Employee Director Compensation

On November 3, 2023, Frequency completed the Merger with Legacy Korro. At the effective time of the Merger, a majority of the Frequency directors resigned, with the exception of David Lucchino, and the remaining director vacancies were replaced by new directors designated by Legacy Korro. Accordingly, we have provided the compensation disclosure with respect to restrictive covenant agreements, pursuant to which she has agreed to refrain from competing with us or soliciting our customers or employeesall directors of Frequency and Legacy Korro that served during her employment2023 and for one year following terminationthose non-employee directors of her employmentLegacy Korro that were appointed to our Board in connection with the Merger.

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We have designed and from disclosingimplemented our proprietary information during or at any time following her employment.

Director compensation

Effective on our IPO, we adopted and our stockholders approved a compensation program for our non-employee directors to attract, motivate and retain individuals who are committed to our values and goals and who have the expertise and experience that we need to achieve those goals.

2023 Director Compensation Table

The following table presents the total compensation for each person who served as a non-employee director on our board of directors during 2023. The non-employee directors included in the following table under the heading Current Non-Employee Directors were our non-employee directors as of December 31, 2023. Dr. Aiyar, our Chief Executive Officer and President, did not receive any additional compensation from us for services on our board of directors. Mr. Lucchino, the Chief Executive Officer and President of Frequency prior to the Merger, did not receive any additional compensation from Frequency for services on Frequency’s board of directors prior to the Merger or from us for services on our board of directors following the Merger. The compensation received by Dr. Aiyar and Mr. Lucchino, respectively, as our named executive officers is set forth above in “—2023 Summary Compensation Table.”