GBIO / Generation Bio Co. - Pengajuan SECLaporan Tahunan, Pernyataan Proksi

Generation Bio Co.

Mga Batayang Estadistika
CIK 1733294
SEC Filings
All companies that sell securities in the United States must register with the Securities and Exchange Commission (SEC) and file reports on a regular basis. These reports include company annual reports (10K, 10Q), news updates (8K), investor presentations (found in 8Ks), insider trades (form 4), ownership reports (13D, and 13G), and reports related to the specific securities sold, such as registration statements and prospectus. This page shows recent SEC filings related to Generation Bio Co.
SEC Filings (Chronological Order)
Halaman ini menyediakan daftar lengkap dan kronologis dari Pengajuan SEC, tidak termasuk pengajuan kepemilikan yang kami sediakan di tempat lain.
August 12, 2025 EX-99.1

Generation Bio Announces New Data for Its Novel ctLNP Delivery System and Early T Cell Programs and Reports Second Quarter 2025 Financial Results ● New data confirm highly selective profile of cell-targeted lipid nanoparticle (ctLNP) and first-ever s

Exhibit 99.1 CONFIDENTIAL Generation Bio Announces New Data for Its Novel ctLNP Delivery System and Early T Cell Programs and Reports Second Quarter 2025 Financial Results ● New data confirm highly selective profile of cell-targeted lipid nanoparticle (ctLNP) and first-ever siRNA delivery to T cells in non-human primates ● Lead siRNA candidates show potent knockdown of LAT1 and VAV1, targets poten

August 12, 2025 EX-10.2

Form of Nonstatutory Stock Option Agreement under 2025 Inducement Stock Incentive Plan

Exhibit 10.2 Generation Bio Co. NONSTATUTORY STOCK OPTION AGREEMENT Granted under 2025 Inducement Stock Incentive Plan Generation Bio Co. (the “Company”) hereby grants the following stock option to the recipient named below pursuant to its 2025 Inducement Stock Incentive Plan (as amended through the date hereof, the “Plan”). The terms and conditions attached hereto are also a part hereof and are i

August 12, 2025 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 12, 2025 Generation Bio Co

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 12, 2025 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Num

August 12, 2025 EX-10.1

2025 Inducement Stock Incentive Plan

Exhibit 10.1 2025 INDUCEMENT STOCK INCENTIVE PLAN OF GENERATION BIO CO. 1. Purpose The purpose of this 2025 Inducement Stock Incentive Plan (the “Plan”) of Generation Bio Co., a Delaware corporation (the “Company”), is to advance the interests of the Company’s stockholders by enhancing the Company’s ability to attract, retain and motivate persons who are expected to make important contributions to

August 12, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39319 GEN

July 18, 2025 EX-99.1

Generation Bio Announces 1-for-10 Reverse Stock Split

Exhibit 99.1 Generation Bio Announces 1-for-10 Reverse Stock Split CAMBRIDGE, Mass. – July 18, 2025 – Generation Bio Co. (Nasdaq: GBIO), a biotechnology company working to change what’s possible for people living with T cell-driven autoimmune diseases, today announced that it will implement a 1-for-10 reverse stock split of the issued shares of the Company’s common stock (“Reverse Stock Split”), e

July 18, 2025 8-K

Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Material Modification to Rights of Security Holders, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 18, 2025 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numbe

July 18, 2025 EX-3.1

Certificate of Amendment of Amended and Restated Certificate of Incorporation of Generation Bio Co.

Exhibit 3.1 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF GENERATION BIO CO. Generation Bio Co., a corporation organized and existing under the General Corporation Law of the State of Delaware (the “Corporation”), hereby certifies as follows: 1. The name of the Corporation is Generation Bio Co. The date of filing of the Corporation’s original Certificate of I

June 5, 2025 8-K

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 4, 2025 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Number

May 7, 2025 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 7, 2025 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Number)

May 7, 2025 EX-99.1

Generation Bio Reports Recent Business Highlights and First Quarter 2025 Financial Results - Company continues to advance its strategy to develop first-in-class treatments for T cell-driven autoimmune diseases using its cell-targeted lipid nanopartic

‌Exhibit 99.1 Generation Bio Reports Recent Business Highlights and First Quarter 2025 Financial Results - Company continues to advance its strategy to develop first-in-class treatments for T cell-driven autoimmune diseases using its cell-targeted lipid nanoparticle (ctLNP) technology to deliver siRNA - Lead target and portfolio strategy to be announced MY 2025 - Cash balance of $157.6 million exp

May 7, 2025 EX-FILING FEES

Calculation of Filing Fee Table

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Generation Bio Co.

May 7, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39319 GE

May 7, 2025 EX-99.2

Form of Nonstatutory Stock Option Agreement Granted under 2025 Inducement Stock Incentive Plan.

Exhibit 99.2 Generation Bio Co. NONSTATUTORY STOCK OPTION AGREEMENT Granted under 2025 Inducement Stock Incentive Plan Generation Bio Co. (the “Company”) hereby grants the following stock option to the recipient named below pursuant to its 2025 Inducement Stock Incentive Plan (as amended through the date hereof, the “Plan”). The terms and conditions attached hereto are also a part hereof and are i

May 7, 2025 S-8

As filed with the Securities and Exchange Commission on May 7, 2025

As filed with the Securities and Exchange Commission on May 7, 2025 Registration No.

May 7, 2025 EX-99.1

2025 Inducement Stock Incentive Plan of Registrant.

Exhibit 99.1 2025 INDUCEMENT STOCK INCENTIVE PLAN OF GENERATION BIO CO. 1. Purpose The purpose of this 2025 Inducement Stock Incentive Plan (the “Plan”) of Generation Bio Co., a Delaware corporation (the “Company”), is to advance the interests of the Company’s stockholders by enhancing the Company’s ability to attract, retain and motivate persons who are expected to make important contributions to

April 23, 2025 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents will UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

April 23, 2025 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Filed by a Party other than the Registrant ☒ Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ Defin

April 11, 2025 PRE 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents will UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

March 13, 2025 EX-10.20

Offer letter, dated December 8, 2017, by and between the registrant and Phillip Samayoa, as amended.

Exhibit 10.20 Generation Bio Co. December 8, 2017 Phillip Samayoa Dear Phillip: On behalf of Generation Bio. Co. (the "Company"), I am pleased to offer you employment with the Company on the following terms and conditions. 1. Position. You will be employed by the Company as a Senior Director of Corporate Development and Portfolio Strategy. It is contemplated that you will commence employment on a

March 13, 2025 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 13, 2025 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numb

March 13, 2025 EX-21.1

Subsidiaries of the registrant.

Exhibit 21.1 Subsidiaries of the Registrant Entity Jurisdiction of Incorporation Generation Bio Securities Corporation Massachusetts

March 13, 2025 EX-10.18

Non-Employee Director Compensation Program.

Exhibit 10.18 GENERATION BIO CO. Non-Employee Director Compensation Program Under Generation Bio Co.’s (the “Company”) non-employee director compensation program, the Company pays its non-employee directors an annual fee. Each non-employee director receives an annual fee for service on the Company’s board of directors (the “Board”) and for service on each committee on which the director is a membe

March 13, 2025 EX-10.28

Offer letter, dated December 8, 2017, by and between the registrant and Kevin Conway, as amended.

Exhibit 10.28 By Electronic Mail June 25th, 2019 Kevin Conway RE: Offer of Employment Dear Kevin: We are very excited to offer you the position of Assistant Corporate Controller where you will play an essential role in building Generation Bio's foundation and long -term business and scientific success. Below are the terms of employment for your review and execution. If these terms are acceptable,

March 13, 2025 EX-10.29

Separation Agreement, by and between the registrant and Matt Norkunas, dated January 13, 2025.

Cambridge, MA 02142 generationbio.com Exhibit 10.29 January 4, 2025 BY E-MAIL *** Dear Matt: This letter agreement (the “Agreement”) confirms the terms of your separation from employment at Generation Bio Co. (the “Company”)1. This Agreement will become effective and enforceable on the eighth day after you sign it without revocation (the “Effective Date”), provided you sign and return the Agreemen

March 13, 2025 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-39

March 13, 2025 EX-99.1

Generation Bio Reports Business Highlights and Fourth Quarter and Full Year 2024 Financial Results - Company is applying its T cell-selective lipid nanoparticle to develop siRNA therapeutics for T cell-driven autoimmune diseases - Lead target and ind

‌Exhibit 99.1 Generation Bio Reports Business Highlights and Fourth Quarter and Full Year 2024 Financial Results - Company is applying its T cell-selective lipid nanoparticle to develop siRNA therapeutics for T cell-driven autoimmune diseases - Lead target and indication to be announced MY 2025 - Cash balance of $185.2 million expected to fund operations into 2H 2027 CAMBRIDGE, MASS., Mar. 13, 202

March 13, 2025 EX-10.30

Consulting Agreement, by and between the registrant and Matt Stanton, dated January 14, 2025 (included in Exhibit 10.30).

Cambridge, MA 02142 generationbio.com Exhibit 10.30 January 3, 2025 BY E-MAIL Matthew Stanton *** *** Dear Matt: This letter agreement (the “Agreement”) confirms the terms of your separation from employment at Generation Bio Co. (the “Company”)1 and the Company’s interest in securing your agreement to provide transition services on an as-needed basis and sets forth the terms and conditions to whic

February 28, 2025 8-K

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 24, 2025 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File N

January 6, 2025 EX-99.1

Generation Bio to Apply ctLNP Delivery Technology to Develop siRNA Therapeutics for T Cell-Driven Autoimmune Diseases - Novel programs will combine validated cell-targeted LNP (ctLNP) delivery with siRNA to selectively modulate T cells in vivo - Prog

Exhibit 99.1   Generation Bio to Apply ctLNP Delivery Technology to Develop siRNA Therapeutics for T Cell-Driven Autoimmune Diseases - Novel programs will combine validated cell-targeted LNP (ctLNP) delivery with siRNA to selectively modulate T cells in vivo - Programs to focus on silencing hard-to-drug targets of high therapeutic value in T cell-driven autoimmune diseases - Company reorganization

January 6, 2025 8-K

Regulation FD Disclosure, Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 6, 2025 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Num

January 3, 2025 EX-FILING FEES

Calculation of Filing Fee Table

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Generation Bio Co.

January 3, 2025 S-8

As filed with the Securities and Exchange Commission on January 3, 2025

As filed with the Securities and Exchange Commission on January 3, 2025 Registration No.

December 9, 2024 SC 13G/A

GBIO / Generation Bio Co. / BB BIOTECH AG - SC 13G/A Passive Investment

SC 13G/A 1 d891686dsc13ga.htm SC 13G/A United States SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 4)* Generation Bio Co. (Name of Issuer) Common Stock (Title of Class of Securities) 37148K100 (CUSIP Number) December 5, 2024 (Date of Event Which Requires Filing This Statement) Check the appropriate box to designate t

November 6, 2024 EX-99.1

Generation Bio Reports Recent Business Highlights and Third Quarter 2024 Financial Results ● Non-human primate data presented at ESGCT demonstrated selective in vivo delivery of mRNA with T cell-targeted lipid nanoparticle (ctLNP) ● Cash balance of $

Generation Bio Reports Recent Business Highlights and Third Quarter 2024 Financial Results ● Non-human primate data presented at ESGCT demonstrated selective in vivo delivery of mRNA with T cell-targeted lipid nanoparticle (ctLNP) ● Cash balance of $199.

November 6, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-3931

November 6, 2024 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 6, 2024 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Nu

August 13, 2024 CORRESP

August 13, 2024

August 13, 2024 VIA EDGAR SUBMISSION Securities and Exchange Commission Division of Corporation Finance 100 F Street, NE Washington, DC 20549 Re: Generation Bio Co.

August 7, 2024 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 7, 2024 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numb

August 7, 2024 EX-99.1

Generation Bio Reports Second Quarter 2024 Financial Results ● Cash balance of $217 million still expected to fund operations into 2H 2027

Exhibit 99.1 Generation Bio Reports Second Quarter 2024 Financial Results ● Cash balance of $217 million still expected to fund operations into 2H 2027 CAMBRIDGE, MASS., Aug. 7, 2024 - Generation Bio Co. (Nasdaq: GBIO), a biotechnology company innovating genetic medicines for people living with rare and prevalent diseases, reported business highlights and second quarter 2024 financial results. “We

August 7, 2024 EX-1.2

Sales Agreement, dated as of August 7, 2024, by and between Generation Bio Co. and TD Securities (USA) LLC

Exhibit 1.2 GENERATION BIO CO. $237,000,000 SALES AGREEMENT August 7, 2024 TD Securities (USA) LLC 1 Vanderbilt Avenue, 11th Floor New York, New York 10017 Ladies and Gentlemen: Generation Bio Co., a Delaware corporation (the “Company”), confirms its agreement (this “Agreement”) with TD Securities (USA) LLC (“TD Cowen”), as follows: 1. Issuance and Sale of Shares. The Company agrees that, from tim

August 7, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39319 GEN

August 7, 2024 EX-4.4

Form of Subordinated Indenture

Exhibit 4.4 GENERATION BIO CO. and Trustee INDENTURE Dated as of SUBORDINATED DEBT SECURITIES CROSS-REFERENCE TABLE 1 Section of Trust Indenture Act of 1939, as amended Section of Indenture 310(a) 6.09 310(b) 6.08 6.10 310(c) Inapplicable 311(a) 6.13 311(b) 6.13 311(c) Inapplicable 312(a) 4.01 4.04 312(b) 4.04(c) 312(c) 4.04(c) 313(a) 4.03 313(b) 4.03 313(c) 4.03 313(d) 4.03 314(a) 4.02 314(b) Ina

August 7, 2024 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) Generation Bio Co.

August 7, 2024 EX-4.3

Form of Senior Indenture

Exhibit 4.3 GENERATION BIO CO. and Trustee INDENTURE Dated as of SENIOR DEBT SECURITIES CROSS-REFERENCE TABLE1 Section of Trust Indenture Act of 1939, as amended Section of Indenture 310(a) 6.09 310(b) 6.08 6.10 310(c) Inapplicable 311(a) 6.13 311(b) 6.13 311(c) Inapplicable 312(a) 4.01 4.04 312(b) 4.04(c) 312(c) 4.04(c) 313(a) 4.03 313(b) 4.03 313(c) 4.03 313(d) 4.03 314(a) 4.02 314(b) Inapplicab

August 7, 2024 EX-4.6

Form of Subordinated Note

Exhibit 4.6 Form of Subordinated Note (FACE OF SECURITY) [Each Global Security shall bear substantially the following legend: UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN DEFINITIVE REGISTERED FORM, THIS SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE

August 7, 2024 S-3

As filed with the Securities and Exchange Commission on August 7, 2024

Table of Contents As filed with the Securities and Exchange Commission on August 7, 2024 Registration No.

August 7, 2024 EX-4.5

Form of Senior Note

Exhibit 4.5 Form of Senior Note (FACE OF SECURITY) [Each Global Security shall bear substantially the following legend: UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN DEFINITIVE REGISTERED FORM, THIS SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE

June 7, 2024 8-K

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 6, 2024 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Number

May 13, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39319 GE

May 13, 2024 EX-10.1

Separation Agreement, by and between the registrant and Doug Kerr, dated January 28, 2024.

Exhibit 10.1 Cambridge, MA 02142 generationbio.com November 29, 2023 Doug Kerr *** *** Re:Separation Agreement Dear Doug: This letter confirms the terms of your transition and separation from employment at Generation Bio Co. (the “Company”).1 As we discussed, the Company is reorganizing and, as a result, your position is being eliminated. You will continue to work and effect a transition of your d

May 13, 2024 EX-10.3

Consulting Agreement, by and between the registrant and Doug Kerr, dated February 1, 2024.

Exhibit 10.3 CONSULTING AGREEMENT GENERATION BIO CONTRACT NO. 21520 This Consulting Agreement (the “Agreement”) dated February 1, 2024 (the “Effective Date”), is made by and between Generation Bio Co., a Delaware corporation having a place of business at 301 Binney St., Suite 401, Cambridge, MA 02421 (the “Company”), and Douglas Kerr, an individual with an address at *** (the “Consultant”). WHEREA

May 13, 2024 EX-99.1

Generation Bio Announces Recent Business Highlights and First Quarter 2024 Financial Results - Oral presentation at ASGCT described selective, high levels of therapeutic transgene delivery to T cells in vivo by cell-targeted lipid nanoparticle (ctLNP

Generation Bio Announces Recent Business Highlights and First Quarter 2024 Financial Results - Oral presentation at ASGCT described selective, high levels of therapeutic transgene delivery to T cells in vivo by cell-targeted lipid nanoparticle (ctLNP) - ASGCT poster presentations described immune-quiet DNA (iqDNA) as partially single-stranded, produced by flexible, scalable, proprietary rapid enzymatic synthesis - Cash balance of $233.

May 13, 2024 EX-10.2

Separation Agreement, by and between the registrant and Tracy Zimmermann, dated January 28, 2024.

Exhibit 10.2 Cambridge, MA 02142 generationbio.com November 29, 2023 Tracy Zimmermann *** *** Re:Separation Agreement Dear Tracy: This letter confirms the terms of your transition and separation from employment at Generation Bio Co. (the “Company”).1 As we discussed, the Company is reorganizing and, as a result, your position is being eliminated. You will continue to work and effect a transition o

May 13, 2024 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 13, 2024 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Number

April 24, 2024 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents will UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

April 24, 2024 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Filed by a Party other than the Registrant ☒ Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ Defin

March 6, 2024 EX-99.1

Generation Bio Reports Business Highlights and Fourth Quarter and Full Year 2023 Financial Results - Company is leveraging proprietary cell-targeted lipid nanoparticle delivery to develop wholly-owned in vivo program for sickle cell disease and beta-

Generation Bio Reports Business Highlights and Fourth Quarter and Full Year 2023 Financial Results - Company is leveraging proprietary cell-targeted lipid nanoparticle delivery to develop wholly-owned in vivo program for sickle cell disease and beta-thalassemia - Development of breakthrough immune-quiet DNA for hemophilia A program continues - Cash balance of $264.

March 6, 2024 EX-21.1

Subsidiaries of the registrant.

Exhibit 21.1 Subsidiaries of the Registrant Entity Jurisdiction of Incorporation Generation Bio Securities Corporation Massachusetts

March 6, 2024 EX-FILING FEES

Calculation of Filing Fee Table

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Generation Bio Co.

March 6, 2024 S-8

As filed with the Securities and Exchange Commission on March 6, 2024

As filed with the Securities and Exchange Commission on March 6, 2024 Registration No.

March 6, 2024 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 6, 2024 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numbe

March 6, 2024 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-39

March 6, 2024 EX-19.1

Insider Trading Policy of the registrant.

Exhibit 19.1 GENERATION BIO CO. Insider Trading Policy 1. BACKGROUND AND PURPOSE The federal securities laws prohibit any member of the Board of Directors (a “Director”), officer (as defined in Rule 16a-1(f) under the Securities Exchange Act of 1934 (the “Exchange Act”), an “executive officer”) or employee of Generation Bio Co. (together with its subsidiaries, the “Company”) from purchasing or sel

March 6, 2024 EX-97.1

Compensation Recovery Policy of the registrant.

Exhibit 97.1 Generation Bio Co. Compensation Recovery Policy This Compensation Recovery Policy (this “Policy”) is adopted by Generation Bio Co. (the “Company”) in accordance with Nasdaq Listing Rule 5608 (“Rule 5608”), which implements Rule 10D-1 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) (as promulgated pursuant to Section 954 of the Dodd-Frank Wall Street Reform a

February 13, 2024 SC 13G/A

GBIO / Generation Bio Co. / BB BIOTECH AG - SC 13G/A Passive Investment

SC 13G/A United States SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 3)* Generation Bio Co. (Name of Issuer) Common Stock (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing This Statement) Check the appropriate box to designate the rule pursuant to which thi

February 9, 2024 SC 13G/A

GBIO / Generation Bio Co. / Atlas Venture Fund X, L.P. - SC 13G/A Passive Investment

SC 13G/A 1 tm245794d2sc13ga.htm SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 2)* Generation Bio Co. (Name of Issuer) COMMON STOCK, $0.0001 PAR VALUE (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing of This Statement) Check the app

February 2, 2024 8-K

Entry into a Material Definitive Agreement, Termination of a Material Definitive Agreement

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 31, 2024 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Nu

January 8, 2024 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 8, 2024 Generation Bio Co

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 8, 2024 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Num

November 29, 2023 EX-99.1

Generation Bio Announces Strategic Reorganization to Extend Cash Runway for Development of ctLNP and iqDNA Platforms - Company to invest in highly selective cell-targeted lipid nanoparticle (ctLNP) delivery platform to develop wholly-owned programs f

Generation Bio Announces Strategic Reorganization to Extend Cash Runway for Development of ctLNP and iqDNA Platforms - Company to invest in highly selective cell-targeted lipid nanoparticle (ctLNP) delivery platform to develop wholly-owned programs for extrahepatic cell types - Development of immune-quiet DNA (iqDNA) platform for lead hemophilia A program to continue - Strategic reorganization will result in a 40% reduction of workforce - Anticipated cost savings to extend cash runway into 2H 2027 CAMBRIDGE, MASS.

November 29, 2023 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 27, 2023 Generation Bio

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 27, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File N

November 9, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-3931

November 9, 2023 EX-99.1

Generation Bio Reports Business Highlights and Third Quarter 2023 Financial Results - Immune-quiet DNA evades innate immune sensors in both mice and non-human primates addressing a central challenge for non-viral DNA therapeutics - Proprietary cell-t

Generation Bio Reports Business Highlights and Third Quarter 2023 Financial Results - Immune-quiet DNA evades innate immune sensors in both mice and non-human primates addressing a central challenge for non-viral DNA therapeutics - Proprietary cell-targeted LNP delivery system showed highly selective T cell transduction in humanized mouse model, demonstrating in vivo targeting for T cells and potentially for other extrahepatic tissues and cell types - Third quarter 2023 cash balance of $291.

November 9, 2023 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 9, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Nu

October 26, 2023 8-K

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): October 26, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Nu

October 26, 2023 EX-99.1

Generation Bio Announces Demonstration of Highly Selective T Cell Transduction In Vivo with Cell-Targeted LNP Platform - 70% of circulating and splenic T cells positive for mRNA expression in humanized mice with less than 8% delivery to off-target im

Generation Bio Announces Demonstration of Highly Selective T Cell Transduction In Vivo with Cell-Targeted LNP Platform - 70% of circulating and splenic T cells positive for mRNA expression in humanized mice with less than 8% delivery to off-target immune cells - Stealth properties of cell-targeted lipid nanoparticle (ctLNP) platform confirmed in non-human primates, demonstrating prolonged circulation and less than 0.

October 18, 2023 8-K

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): October 18, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Nu

October 18, 2023 EX-99.1

Medicine Platform with Novel “Immune-Quiet” DNA

Generation Bio Announces Breakthrough in its Non-Viral Genetic Medicine Platform with Novel “Immune-Quiet” DNA -Immune-quiet DNA (iqDNA) is a novel variant of closed-ended DNA (ceDNA) that evades host innate immune detection in both mice and non-human primates (NHPs) with a systemic cytokine profile and tolerability comparable to mRNA -Company is advancing iqDNA in lieu of prior ceDNA constructs a

August 2, 2023 EX-3.1

Restated Certificate of Incorporation of the Registrant, as amended (incorporated by reference to Exhibit 3.1 to the Registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed August 2, 2023).

Exhibit 3.1 AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF GENERATION BIO CO. Generation Bio Co., a corporation organized and existing under the General Corporation Law of the State of Delaware, does hereby certify that the name of the corporation is Generation Bio Co. and the original certificate of incorporation of the corporation was filed with the Secretary of State of the State of Delaw

August 2, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39319 GEN

August 2, 2023 EX-99.1

Generation Bio Reports Second Quarter 2023 Financial Results Second quarter 2023 cash balance of $314.1 million expected to fund operations into 2025

Generation Bio Reports Second Quarter 2023 Financial Results Second quarter 2023 cash balance of $314.

August 2, 2023 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 2, 2023 Generation Bio Co.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 2, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numb

June 9, 2023 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 8, 2023 Generation Bio Co. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 8, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Number

May 10, 2023 EX-10.1

Offer letter, dated March 17, 2023, by and between the registrant and Yalonda Howze, as amended (incorporated by reference to Exhibit 10.1 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed May 10, 2023).

Exhibit 10.1 By Electronic Mail March 17, 2023 Yalonda Howze *** *** RE: Offer of Employment Dear Yalonda: We are very excited to offer you the position of Chief Legal Officer where you will play an essential role in building Generation Bio’s foundation and long-term business and scientific success. Below are the terms of employment for your review and execution. If these terms are acceptable, ple

May 10, 2023 EX-99.1

Generation Bio Reports Business Highlights and First Quarter 2023 Financial Results Company entered into strategic collaboration with Moderna to use Generation Bio’s proprietary non-viral genetic medicine delivery system for two liver disease program

Generation Bio Reports Business Highlights and First Quarter 2023 Financial Results Company entered into strategic collaboration with Moderna to use Generation Bio’s proprietary non-viral genetic medicine delivery system for two liver disease programs and to co-develop novel targeting for immune cells Factor VIII expression data in non-human primates for wholly-owned hemophilia A program expected in 2023 First quarter 2023 cash balance of $288.

May 10, 2023 EX-10.2

Collaboration and License Agreement, dated March 23, 2023, by and between the registrant and ModernaTX, Inc. (incorporated by reference to Exhibit 10.2 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed May 10, 2023).

Exhibit 10.2 Certain identified information has been excluded from the exhibit because it is both (i) not material and (ii) is the type of information that the registrant treats as private or confidential. Double asterisks denote omissions. COLLABORATION AND LICENSE AGREEMENT between GENERATION BIO CO. and MODERNATX, INC. dated March 23, 2023 TABLE OF CONTENTS Page ARTICLE 1 - DEFINITIONS AND INTE

May 10, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39319 GE

May 10, 2023 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 10, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Number

May 10, 2023 EX-10.3

Share Purchase Agreement, dated March 23, 2023, by and between the registrant and ModernaTX, Inc. (incorporated by reference to Exhibit 10.3 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed May 10, 2023).

Exhibit 10.3 Execution Version Certain identified information has been excluded from the exhibit because it is both (i) not material and (ii) is the type of information that the registrant treats as private or confidential. Double asterisks denote omissions. SHARE PURCHASE AGREEMENT By and Between MODERNATX, INC. AND GENERATION BIO CO. Dated as of March 23, 2023 TABLE OF CONTENTS Page 1. Definitio

April 26, 2023 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents will UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

April 26, 2023 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Filed by a Party other than the Registrant ☒ Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ Defin

April 10, 2023 PRE 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents will UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

April 5, 2023 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 31, 2023 Generation Bio Co.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 31, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numb

April 4, 2023 EX-3.1

Amended and Restated Bylaws of the Registrant (incorporated by reference to Exhibit 3.1 to the Registrant’s Current Report on Form 8-K, File No. 001-39319, filed April 4, 2023).

Exhibit 3.1 AMENDED AND RESTATED BYLAWS OF GENERATION BIO CO. TABLE OF CONTENTS Page ARTICLE I STOCKHOLDERS 1 1.1 Place of Meetings 1 1.2 Annual Meeting 1 1.3 Special Meetings 1 1.4 Record Date for Stockholder Meetings 1 1.5 Notice of Meetings 1 1.6 Voting List 1 1.7 Quorum 2 1.8 Adjournments 2 1.9 Voting and Proxies 2 1.10 Action at Meeting 2 1.11 Nomination of Directors 3 1.12 Notice of Business

April 4, 2023 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 31, 2023 Generation Bio Co.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 31, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numb

March 24, 2023 SC 13G

GBIO / Generation Bio Co / ModernaTX, Inc. - SC 13G Passive Investment

SC 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. ) * Generation Bio Co. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 37148K100 (CUSIP Number) March 24, 2023 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the

March 23, 2023 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 23, 2023 Generation Bio Co.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 23, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numb

March 10, 2023 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 10, 2023 Generation Bio Co.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 10, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numb

February 23, 2023 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-39

February 23, 2023 EX-21.1

Subsidiaries of the registrant.

Exhibit 21.1 Subsidiaries of the Registrant Entity Jurisdiction of Incorporation Generation Bio Securities Corporation Massachusetts

February 23, 2023 EX-99.1

Generation Bio Outlines 2023 Strategic Priorities and Reports Fourth Quarter and Full Year 2022 Financial Results - Company expects to announce data for Factor VIII expression in non-human primates in 2023 - Strong cash balance of $279.1M provides ex

Generation Bio Outlines 2023 Strategic Priorities and Reports Fourth Quarter and Full Year 2022 Financial Results - Company expects to announce data for Factor VIII expression in non-human primates in 2023 - Strong cash balance of $279.

February 23, 2023 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 23, 2023 Generation Bio

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 23, 2023 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File N

February 14, 2023 SC 13G/A

GBIO / Generation Bio Co / PFM Health Sciences, LP - SC 13G/A Passive Investment

SC 13G/A 1 tm235475d6sc13g.htm SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G (Rule 13d-102) Information Statement Pursuant to Rules 13d-1 and 13d-2 Under the Securities Exchange Act of 1934 (Amendment No. 1)* Generation Bio Co. (Name of Issuer) Common stock, par value $0.0001 per share (Title of Class of Securities) 37148K100 (CUSIP Number) December

February 14, 2023 SC 13G/A

GBIO / Generation Bio Co / BB BIOTECH AG - SC 13G/A Passive Investment

SC 13G/A United States SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 2)* Generation Bio Co. (Name of Issuer) Common Stock (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2022 (Date of Event Which Requires Filing This Statement) Check the appropriate box to designate the rule pursuant to which thi

February 14, 2023 EX-99.B

POWER OF ATTORNEY

EX-99.B 2 d405438dex99b.htm EX-99.B Exhibit B POWER OF ATTORNEY The Undersigned, Hugo van Neutegem herewith gives Power of Attorney to Mrs. Nathalie M.A. Isidora-Kwidama, born in Curacao on, holder of a passport issued by the Kingdom of the Netherlands, with number, to represent the Company in the broadest sense of the word and in the best interest of the Company and further to do if were the Unde

February 9, 2023 SC 13G/A

GBIO / Generation Bio Co / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SC 13G/A 1 tv0971-generationbioco.htm SCHEDULE 13G/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 1)* Name of issuer: Generation Bio Co. Title of Class of Securities: Common Stock CUSIP Number: 37148K100 Date of Event Which Requires Filing of this Statement: December 30, 2022 Check the appropriate box to designate

February 1, 2023 SC 13G/A

GBIO / Generation Bio Co / Farallon Capital Partners, L.P. - AMENDMENT #3 Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

January 12, 2023 EX-FILING FEES

Calculation of Filing Fee Table

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Generation Bio Co.

January 12, 2023 S-8

As filed with the Securities and Exchange Commission on January 12, 2023

As filed with the Securities and Exchange Commission on January 12, 2023 Registration No.

November 3, 2022 EX-10.1

Offer letter, dated December 8, 2017, by and between the registrant and Phillip Samayoa, as amended (incorporated by reference to Exhibit 10.1 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed November 3, 2022).

Exhibit 10.1 ? Generation Bio Co. ? ? ? ? December 8, 2017 ? Phillip Samayoa ? ? ? Dear Phillip: ? On behalf of Generation Bio. Co. (the "Company"), I am pleased to offer you employment with the Company on the following terms and conditions. ? 1. Position. You will be employed by the Company as a Senior Director of Corporate Development and Portfolio Strategy. It is contemplated that you will comm

November 3, 2022 EX-99.1

Generation Bio Reports Business Highlights and Third Quarter 2022 Financial Results Cash balance of $301.2M expected to fund operations into 2025

Generation Bio Reports Business Highlights and Third Quarter 2022 Financial Results ? Cash balance of $301.

November 3, 2022 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

November 3, 2022 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 3, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission

September 20, 2022 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): September 15, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File

September 6, 2022 SC 13G

GBIO / Generation Bio Co / PFM Health Sciences, LP - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G (Rule 13d-102) Information Statement Pursuant to Rules 13d-1 and 13d-2 Under the Securities Exchange Act of 1934 (Amendment No. )* Generation Bio Co. (Name of Issuer) Common stock, par value $0.0001 per share (Title of Class of Securities) 37148K100 (CUSIP Number) August 25, 2022 (Date of Event Which Requires Fili

September 6, 2022 EX-99.1

JOINT FILING AGREEMENT

EXHIBIT 99.1 JOINT FILING AGREEMENT The undersigned hereby agree that the Statement on Schedule 13G filed herewith (and any amendments thereto), relating to the common stock of Generation Bio Co., a Delaware corporation, is being filed jointly with the Securities and Exchange Commission pursuant to Rule 13d-1(c) under the Securities Exchange Act of 1934, as amended, on behalf of each of the unders

August 4, 2022 EX-99.1

Generation Bio Reports Business Highlights and Second Quarter 2022 Financial Results Cash balance of $312.2M expected to fund operations into 2025

Generation Bio Reports Business Highlights and Second Quarter 2022 Financial Results ? Cash balance of $312.

August 4, 2022 EX-10.1

Non-Employee Director Compensation Program (incorporated by reference to Exhibit 10.1 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed August 4, 2022).

Exhibit 10.1 ? GENERATION BIO CO. Non-Employee Director Compensation Program Under Generation Bio Co.?s (the ?Company?) non-employee director compensation program, the Company pays its non-employee directors an annual fee. Each non-employee director receives an annual fee for service on the Company?s board of directors (the ?Board?) and for service on each committee on which the director is a memb

August 4, 2022 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 4, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission F

August 4, 2022 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

July 18, 2022 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 15, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission Fi

June 21, 2022 EX-99.1

Generation Bio Announces Update to Its GMP Manufacturing Strategy Company projects smaller GMP manufacturing footprint, enabled by further process development of rapid enzymatic synthesis of ceDNA at scale Company will seek to sublease its planned GM

? Generation Bio Announces Update to Its GMP Manufacturing Strategy ? Company projects smaller GMP manufacturing footprint, enabled by further process development of rapid enzymatic synthesis of ceDNA at scale ? Company will seek to sublease its planned GMP facility, and will adopt a more capital efficient, modular, and flexible manufacturing approach ? Capital reallocated from facility buildout expected to extend cash runway into 2025 ? Cambridge, Mass.

June 21, 2022 8-K

Financial Statements and Exhibits, Other Events

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 21, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission Fi

June 10, 2022 8-K

Submission of Matters to a Vote of Security Holders

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 9, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission Fil

May 5, 2022 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39319 GE

May 5, 2022 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 5, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Number)

May 5, 2022 EX-10.2

Third Amendment to Lease, dated February 24, 2022, by and between the registrant and BMR-Rogers Street LLC (incorporated by reference to Exhibit 10.2 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed May 5, 2022).

‌ Exhibit 10.2 THIRD AMENDMENT TO LEASE THIS THIRD AMENDMENT TO LEASE (this "Amendment") is entered into as of this 24th day of February, 2022 (the "Effective Date"), by and between BMR-ROGERS STREET LLC, a Delaware limited liability company ("Landlord"), and GENERATION BIO CO., a Delaware corporation ("Tenant"). RECITALS A.WHEREAS, Landlord and Tenant are parties to that certain Lease dated as of

May 5, 2022 EX-99.1

Generation Bio Reports Business Highlights and First Quarter 2022 Financial Results Company continues to optimize cell-targeted lipid nanoparticle (ctLNP) delivery system for nonviral genetic medicine applications in liver, retina and vaccines Cash b

Generation Bio Reports Business Highlights and First Quarter 2022 Financial Results Company continues to optimize cell-targeted lipid nanoparticle (ctLNP) delivery system for nonviral genetic medicine applications in liver, retina and vaccines Cash balance of $337.

April 26, 2022 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) ? ? ? ? ? Filed by the Filed by a Party other than the Registrant ? ? Registrant ? ? ? Check the appropriate box: ? ? ? ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by

April 26, 2022 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

February 24, 2022 EX-99.1

Generation Bio Outlines 2022 Strategic Priorities and Reports Fourth Quarter and Full Year 2021 Financial Results Well-capitalized with $375.1 million at the end of 2021, funding planned operations into 2024

? ? Generation Bio Outlines 2022 Strategic Priorities and Reports Fourth Quarter and Full Year 2021 Financial Results ? Well-capitalized with $375.

February 24, 2022 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 24, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commissio

February 24, 2022 POSASR

Post-Effective Amendment No. 1

Table of Contents As filed with the Securities and Exchange Commission on February 24, 2022 Registration No.

February 24, 2022 POS AM

As filed with the Securities and Exchange Commission on February 24, 2022

Table of Contents As filed with the Securities and Exchange Commission on February 24, 2022 Registration No.

February 24, 2022 EX-FILING FEES

Calculation of Filing Fee Table

EX-FILING FEES 4 tmb-20220224xexfilingfees.htm EX-FILING FEES Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Generation Bio Co. (Exact Name of Registrant as Specified in its Charter) Table 1 – Newly Registered Securities Security Type Security Class Title Fee Calculation Rule Amount Registered (1) Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate

February 24, 2022 EX-FILING FEES

Calculation of Filing Fee Tables

Exhibit 107 Calculation of Filing Fee Tables Post-Effective Amendment No 1 to Form S-3 (Form Type) Generation Bio Co.

February 24, 2022 EX-10.21

Offer letter, dated October 11, 2018, by and between the registrant and Antoinette Paone, as amended (incorporated by reference to Exhibit 10.21 to the registrant’s Annual Report on Form 10-K, File No. 001-39319, filed February 24, 2022).

? ? ?Exhibit 10.21 ? By Electronic Moil ? October 11, 2018 ? Antoinette Drahus Paone ? RE: Offer of Employment ? Dear Antoinette: ? We are very excited to offer you the position of Vice President, Regulatory Affairs where you will play an essential role in building Generation Bio's foundation and long -term business and scientific success. Below are the terms of employment for your review and exec

February 24, 2022 EX-21.1

Subsidiaries of the registrant.

Exhibit 21.1 ? Subsidiaries of the Registrant ? ? ? ? Entity Jurisdiction of Incorporation Generation Bio Securities Corporation ? Massachusetts ?

February 24, 2022 EX-10.20

Offer letter, dated September 5, 2017, by and between the registrant and Matthew Stanton, as modified by Promotion letter, dated May 22, 2019 (incorporated by reference to Exhibit 10.20 to the registrant’s Annual Report on Form 10-K, File No. 001-39319, filed February 24, 2022).

Exhibit 10.20 Torus Therapeutics, Inc. ? ? ? ? September 5, 2017 ? Matthew Stanton ? Dear Matt: On behalf of Torus Therapeutics (the "Company"), I am pleased to offer you employment with the Company on the following terms and conditions. 1.Position. You will be employed by the Company as the Chief Technology Officer. It is contemplated that you will commence employment on a date to be mutually agr

February 24, 2022 EX-10.22

Amendment #2 to Exclusive License Agreement, dated January 25, 2022, by and between the registrant and the University of Massachusetts (incorporated by reference to Exhibit 10.22 to the registrant’s Annual Report on Form 10-K, File No. 001-39319, filed February 24, 2022).

Exhibit 10.22 Certain identified information has been marked in the exhibit because it is both (i) not material and (ii) would likely cause competitive harm to the Company, if publicly disclosed. Double asterisks denote omissions. ? AMENDMENT # 2 TO EXCLUSIVE LICENSE AGREEMENT Between Generation Bio and UMASS Chan Medical School ? This Amendment #2 (?Amendment 2?) expressly amends and relates to t

February 24, 2022 EX-10.23

Non-Employee Director Compensation Program.

Exhibit 10.23 ? GENERATION BIO CO. Non-Employee Director Compensation Program Under Generation Bio Co.?s (the ?Company?) non-employee director compensation program, the Company pays its non-employee directors an annual fee. Each non-employee director receives an annual fee for service on the Company?s board of directors (the ?Board?) and for service on each committee on which the director is a mem

February 24, 2022 S-8

As filed with the Securities and Exchange Commission on February 24, 2022

As filed with the Securities and Exchange Commission on February 24, 2022 Registration No.

February 24, 2022 10-K

Form 10-K

Table of Contents ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

February 11, 2022 SC 13G/A

GBIO / Generation Bio Co / Atlas Venture Fund X, L.P. - AMENDMENT TO SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Generation Bio Co. (Name of Issuer) COMMON STOCK, $0.0001 PAR VALUE (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursua

February 11, 2022 EX-1

Joint Filing Agreement

Atlas Venture Fund X, L.P. SC 13G/A Exhibit A JOINT FILING AGREEMENT In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned agree to the joint filing on behalf of each of them of a statement on Schedule 13G (including amendments thereto) with respect to the Common Stock of Generation Bio Co. and further agree that this agreement be included as an ex

February 11, 2022 SC 13G/A

GBIO / Generation Bio Co / BB BIOTECH AG - SC 13G/A Passive Investment

United States SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Generation Bio Co. (Name of Issuer) Common Stock (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing This Statement) Check the appropriate box to designate the rule pursuant to which this Schedul

February 11, 2022 SC 13G/A

GBIO / Generation Bio Co / Artal International S.C.A. - SC 13G/A Passive Investment

SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934* (Amendment No. 2) Generation Bio Co. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designat

February 10, 2022 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 4, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission

February 10, 2022 SC 13G

GBIO / Generation Bio Co / VANGUARD GROUP INC - SCHEDULE 13G Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 Name of issuer: Generation Bio Co. Title of Class of Securities: Common Stock CUSIP Number: 37148K100 Date of Event Which Requires Filing of this Statement: December 31, 2021 Check the appropriate box to designate the rule pursuant to which this Schedule is filed: ??Rule 13d-1(b) ??Rule

February 3, 2022 SC 13G/A

GBIO / Generation Bio Co / FARALLON CAPITAL MANAGEMENT LLC - AMENDMENT #2 Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

January 10, 2022 8-K

Other Events

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 10, 2022 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission

December 14, 2021 EX-99.1

Generation Bio Provides Update on Preclinical Studies for Hemophilia A Program - Innovations in closed-ended DNA (ceDNA) and cell-targeted lipid nanoparticle (ctLNP) production processes generated peak mean of 205% normal human factor VIII expression

EX-99.1 2 gbio-20211214xex99d1.htm EX-99.1 Generation Bio Provides Update on Preclinical Studies for Hemophilia A Program - Innovations in closed-ended DNA (ceDNA) and cell-targeted lipid nanoparticle (ctLNP) production processes generated peak mean of 205% normal human factor VIII expression in mice - Non-human primates (NHPs) demonstrated up to 2% normal human factor VIII expression, and higher-

December 14, 2021 8-K

Financial Statements and Exhibits, Other Events

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 14, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commissio

November 10, 2021 EX-99.1

Generation Bio Reports Business Highlights and Third Quarter 2021 Financial Results New preclinical retinal data illustrating potential for expansive therapeutic applications of ctLNP delivery presented at ESGCT 2021 Annual Virtual Congress

? ? Generation Bio Reports Business Highlights and Third Quarter 2021 Financial Results ? New preclinical retinal data illustrating potential for expansive therapeutic applications of ctLNP delivery presented at ESGCT 2021 Annual Virtual Congress ? CAMBRIDGE, MASS.

November 10, 2021 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 10, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commissio

November 10, 2021 EX-10.1

Lease, dated July 13, 2021, by and between the registrant and Zinc II PropCo 2020, LLC (incorporated by reference to Exhibit 10.1 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed November 10, 2021).

? ? ? ? ? 41 SEYON STREET WALTHAM, MASSACHUSETTS ? ? Lease to ? GENERATION BIO CO.

November 10, 2021 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

August 11, 2021 S-3ASR

As filed with the Securities and Exchange Commission on August 11, 2021

Table of Contents As filed with the Securities and Exchange Commission on August 11, 2021 Registration No.

August 11, 2021 EX-99.1

Generation Bio Reports Business Highlights and Second Quarter 2021 Financial Results

Exhibit 99.1 ? ? ? Generation Bio Reports Business Highlights and Second Quarter 2021 Financial Results ? ? CAMBRIDGE, MASS., Aug. 11, 2021 - Generation Bio Co. (Nasdaq: GBIO), a biotechnology company innovating genetic medicines for people living with rare and prevalent diseases, reported recent business highlights and second quarter 2021 financial results. ? ?This quarter we announced our shift

August 11, 2021 EX-1.2

Sales Agreement, dated as of August 11, 2021, by and between the registrant and Cowen and Company, LLC (incorporated by reference Exhibit 1.2 to the registrant’s Registration Statement on Form S-3, File No. 333-258723, filed August 11, 2021)

Exhibit 1.2 GENERATION BIO CO. $250,000,000 SALES AGREEMENT August 11, 2021 Cowen and Company, LLC 599 Lexington Avenue New York, NY 10022 Ladies and Gentlemen: Generation Bio Co., a Delaware corporation (the ?Company?), confirms its agreement (this ?Agreement?) with Cowen and Company, LLC (?Cowen?), as follows: 1. Issuance and Sale of Shares. The Company agrees that, from time to time during the

August 11, 2021 EX-4.4

Form of Subordinated Indenture (incorporated by reference to Exhibit 4.4 to the registrant’s Registration Statement on Form S-3, File No. 333-258732, filed August 11, 2021)

Exhibit 4.4 GENERATION BIO CO. and Trustee INDENTURE Dated as of SUBORDINATED DEBT SECURITIES CROSS-REFERENCE TABLE 1 Section of Trust Indenture Act of 1939, as amended Section of Indenture 310(a) 6.09 310(b) 6.08 6.10 310(c) Inapplicable 311(a) 6.13 311(b) 6.13 311(c) Inapplicable 312(a) 4.01 4.04 312(b) 4.04(c) 312(c) 4.04(c) 313(a) 4.03 313(b) 4.03 313(c) 4.03 313(d) 4.03 314(a) 4.02 314(b) Ina

August 11, 2021 EX-4.6

Form of Subordinated Note (incorporated by reference to Exhibit 4.6 to the registrant’s Registration Statement on Form S-3, File No. 333-258732, filed August 11, 2021)

Exhibit 4.6 Form of Subordinated Note (FACE OF SECURITY) [Each Global Security shall bear substantially the following legend: UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN DEFINITIVE REGISTERED FORM, THIS SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE

August 11, 2021 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 11, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission

August 11, 2021 EX-4.3

Form of Senior Indenture (incorporated by reference to Exhibit 4.3 to the registrant’s Registration Statement on Form S-3, File No. 333-258732, filed August 11, 2021)

Exhibit 4.3 GENERATION BIO CO. and Trustee INDENTURE Dated as of SENIOR DEBT SECURITIES CROSS-REFERENCE TABLE1 Section of Trust Indenture Act of 1939, as amended Section of Indenture 310(a) 6.09 310(b) 6.08 6.10 310(c) Inapplicable 311(a) 6.13 311(b) 6.13 311(c) Inapplicable 312(a) 4.01 4.04 312(b) 4.04(c) 312(c) 4.04(c) 313(a) 4.03 313(b) 4.03 313(c) 4.03 313(d) 4.03 314(a) 4.02 314(b) Inapplicab

August 11, 2021 EX-4.5

Form of Senior Note (incorporated by reference to Exhibit 4.5 to the registrant’s Registration Statement on Form S-3, File No. 333-258732, filed August 11, 2021)

Exhibit 4.5 Form of Senior Note (FACE OF SECURITY) [Each Global Security shall bear substantially the following legend: UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN DEFINITIVE REGISTERED FORM, THIS SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE

August 11, 2021 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

July 14, 2021 EX-99.1

Generation Bio Announces Plan to Scale Next-Generation Rapid Enzymatic Manufacturing Process Across Portfolio and Provides Pipeline Update Company to transition all portfolio programs to rapid enzymatic synthesis (RES), enabling improved quality, sca

? ? ? Generation Bio Announces Plan to Scale Next-Generation Rapid Enzymatic Manufacturing Process Across Portfolio and Provides Pipeline Update ? Company to transition all portfolio programs to rapid enzymatic synthesis (RES), enabling improved quality, scale and speed of closed-ended DNA manufacturing ? Lease agreement signed to build an in-house RES manufacturing facility providing cGMP capacity for and internal control over clinical and initial commercial supply ? IND submission for hemophilia A now planned for 2023; factor VIII expression data with RES material in non-human primates expected year-end 2021 ? Cambridge, Mass.

July 14, 2021 8-K

Entry into a Material Definitive Agreement, Financial Statements and Exhibits

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 13, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission Fi

June 10, 2021 8-K

Submission of Matters to a Vote of Security Holders

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 9, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission Fil

May 12, 2021 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 12, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commission Fil

May 12, 2021 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

May 12, 2021 EX-99.1

Generation Bio Presents Preclinical Data Demonstrating Broad Potential of Gene Therapy Platform at ASGCT and Reports First Quarter Financial Results Durable, therapeutically relevant levels of anti-SARS-CoV-2 spike antibodies produced from the liver

? ? Generation Bio Presents Preclinical Data Demonstrating Broad Potential of Gene Therapy Platform at ASGCT and Reports First Quarter Financial Results ? Durable, therapeutically relevant levels of anti-SARS-CoV-2 spike antibodies produced from the liver in a mouse model ? Next-generation rapid enzymatic synthesis of closed-ended DNA further increases the efficiency and scale of the manufacturing platform ? Potent factor VIII construct optimized by taking advantage of the increased cargo capacity of closed-ended DNA ? CAMBRIDGE, MASS.

April 27, 2021 DEFA14A

- DEFA14A

Table of Contents ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

April 27, 2021 DEF 14A

definitive proxy statement

DEF 14A 1 tmb-20210609xdef14a.htm DEF 14A Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Filed by a Party other than the Registrant ☒ Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of th

March 18, 2021 EX-99.1

Generation Bio Reports Fourth Quarter and Full Year 2020 Financial Results $262.3 million cash balance at the end of 2020 bolstered by additional net proceeds of $211.3 million from follow-on offering, funding key milestones into 2024 Ron Cooper appo

EX-99.1 Exhibit 99.1 Generation Bio Reports Fourth Quarter and Full Year 2020 Financial Results $262.3 million cash balance at the end of 2020 bolstered by additional net proceeds of $211.3 million from follow-on offering, funding key milestones into 2024 Ron Cooper appointed to Board of Directors Company remains on track to begin IND-enabling studies for hemophilia A in 2021 CAMBRIDGE, MASS., Mar

March 18, 2021 10-K

Annual Report - 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2020 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-39

March 18, 2021 S-8

- S-8

As filed with the Securities and Exchange Commission on March 18, 2021 Registration No.

March 18, 2021 EX-21.1

Subsidiaries of the registrant.

Exhibit 21.1 Subsidiaries of the Registrant Entity Jurisdiction of Incorporation Generation Bio Securities Corporation Massachusetts

March 18, 2021 EX-4.3

Exhibit 4.3

Exhibit 4.3 DESCRIPTION OF REGISTRANT?S SECURITIES REGISTERED PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED The following description of the capital stock and provisions of Generation Bio Co.?s (the ?Company,? ?we,? ?us? and/or ?our?) restated certificate of incorporation and amended and restated bylaws are summaries and are qualified by reference to our restated certif

March 18, 2021 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): March 18, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File Numb

February 18, 2021 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 17, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) ? Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) ? (Commissio

February 18, 2021 EX-99.1

Generation Bio Appoints Ron Cooper to its Board of Directors

Generation Bio Appoints Ron Cooper to its Board of Directors CAMBRIDGE, MASS., February 18, 2021 - Generation Bio Co. (Nasdaq: GBIO), an innovative genetic medicines company creating a new class of gene therapy, announced today that Ron Cooper has been appointed to its Board of Directors. The appointment is effective March 1, 2021. Ron Cooper is a global biopharmaceutical executive who currently s

February 16, 2021 EX-99.1

JOINT FILING AGREEMENT

Exhibit 1 EXHIBIT 1 JOINT FILING AGREEMENT The undersigned agree that the statement on Schedule 13G with respect to the common stock, $0.

February 16, 2021 SC 13G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934* (Amendment No. 1) Generation Bio Co. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securit

SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934* (Amendment No. 1) Generation Bio Co. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2020 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designat

February 16, 2021 SC 13G

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Generation Bio Co. (Name of Issuer) COMMON STOCK, $0.0001 PAR VALUE (Title of Class of Securities) (CUSIP

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Generation Bio Co. (Name of Issuer) COMMON STOCK, $0.0001 PAR VALUE (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2020 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursuant

January 15, 2021 SC 13G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1) *

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

January 8, 2021 SC 13G

United States SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 Generation Bio Co. (Name of Issuer) Common Stock (Title of Class of Securities) (CUSIP Number) December 31, 2020 (Date of E

SC 13G United States SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 Generation Bio Co. (Name of Issuer) Common Stock (Title of Class of Securities) 37148K100 (CUSIP Number) December 31, 2020 (Date of Event Which Requires Filing This Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

January 7, 2021 424B4

Joint bookrunning managers J.P. Morgan Jefferies Cowen Lead manager Wedbush PacGrow

424B4 Table of Contents File Pursuant to Rule 424(b)(4) Registration No. 333-251872 Prospectus 8,000,000 shares Common stock We are offering 8,000,000 shares of our common stock in this offering. Our common stock is listed on the Nasdaq Global Select Market under the symbol “GBIO.” The last reported sale price of our common stock on the Nasdaq Global Select Market on January 6, 2021 was $24.74 per

January 6, 2021 S-1MEF

- S-1MEF

S-1MEF As filed with the Securities and Exchange Commission on January 6, 2021 Registration No.

January 4, 2021 CORRESP

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CORRESP 1 filename1.htm Generation Bio Co. 301 Binney Street Cambridge, MA 02142 January 4, 2021 VIA EDGAR U.S. Securities and Exchange Commission Division of Corporation Finance, Office of Life Sciences 100 F Street, N.E. Washington, D.C. 20549 Attention: Abby Adams Re: Generation Bio Co. Registration Statement on Form S-1 File No. 333-251872 Request for Acceleration Ladies and Gentlemen: Pursuan

January 4, 2021 8-K

Results of Operations and Financial Condition - 8-K

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 4, 2021 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File

January 4, 2021 EX-1.1

Form of Underwriting Agreement

EX-1.1 Exhibit 1.1 Generation Bio Co. [•] Shares of Common Stock Underwriting Agreement [•], 2021 J.P. Morgan Securities LLC Jefferies LLC Cowen and Company, LLC As Representatives of the several Underwriters listed in Schedule 1 hereto c/o J.P. Morgan Securities LLC 383 Madison Avenue New York, New York 10179 c/o Jefferies LLC 520 Madison Avenue New York, New York 10022 c/o Cowen and Company, LLC

January 4, 2021 S-1

Power of Attorney (incorporated by reference to the signature page to the Registrant’s Registration Statement on Form S-1 (File No. 333-251872) filed with the Commission on January 4, 2021)

S-1 Table of Contents As filed with the Securities and Exchange Commission on January 4, 2021 Registration No.

January 4, 2021 EX-10.20

Offer letter, dated August 26, 2018, by and between the registrant and Tracy Zimmermann, as modified by Promotion letter, dated November 10, 2020 (incorporated by reference to Exhibit 10.20 to the registrant’s Registration Statement on Form S-1, File No. 333-251872, filed January 4, 2021).

EX-10.20 Exhibit 10.20 By Electronic Mail August 22, 2018 Tracy Zimmermann, Ph.D. RE: Offer of Employment Dear Tracy, We are very excited to offer you the position of Vice President Preclinical and Translational Biology where you will play an essential role in building Generation Bio’s foundation and long -term business and scientific success. Below are the terms of employment for your review and

January 4, 2021 CORRESP

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UW Acceleration Request J.P. Morgan Securities LLC 383 Madison Avenue New York, New York 10179 Jefferies LLC 520 Madison Avenue New York, New York 10022 Cowen and Company, LLC 599 Lexington Avenue New York, New York 10010 January 4, 2021 VIA EDGAR U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, D.C. 20549 Re: Generation Bio Co. Registration St

December 21, 2020 DRS

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DRS Table of Contents Confidential Treatment Requested by Generation Bio Co. Pursuant to 17 C.F.R. Section 200.83 As confidentially submitted to the Securities and Exchange Commission on December 21, 2020. This draft registration statement has not been publicly filed with the Securities and Exchange Commission and all information herein remains strictly confidential. Registration No. 333- UNITED S

November 10, 2020 10-Q

Quarterly Report - 10-Q

10-Q Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

November 10, 2020 EX-99.1

Generation Bio Reports Third Quarter 2020 Business Updates and Financial Results On Track to Advance Lead Programs into Pre-Clinical Development in 2021 Supported by Key Leadership Team Appointments

EX-99.1 Exhibit 99.1 Generation Bio Reports Third Quarter 2020 Business Updates and Financial Results On Track to Advance Lead Programs into Pre-Clinical Development in 2021 Supported by Key Leadership Team Appointments Cambridge, Mass. – Nov. 10, 2020 – Generation Bio Co. (Nasdaq: GBIO) is an innovative genetic medicines company creating a new class of non-viral gene therapy. Today the company re

November 10, 2020 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits, Results of Operations and Financial Condition - 8-K

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 5, 2020 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission Fil

August 11, 2020 10-Q

Quarterly Report - 10-Q

10-Q UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2020 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-39319 GENERATION BIO C

August 11, 2020 EX-10.1

Lease, dated August 2, 2018, by and between the registrant and BMR-Rogers Street LLC, as amended (incorporated by reference to Exhibit 10.1 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed August 11, 2020).

EX-10.1 Exhibit 10.1 LEASE by and between BMR-ROGERS STREET LLC, a Delaware limited liability company and GENERATION BIO CO., a Delaware corporation TABLE OF CONTENTS Page 1. Lease of Premises 1 2. Basic Lease Provisions 2 3. Term 5 4. Possession and Commencement Date 5 5. Condition of Premises 8 6. Rentable Area 8 7. Rent 9 8. Rent Adjustments 10 9. Operating Expenses 10 10. Taxes on Tenant’s Pro

August 11, 2020 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition - 8-K

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 11, 2020 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File

August 11, 2020 EX-10.2

Offer letter, dated June 19, 2020, by and between the registrant and Matthew Norkunas, as amended July 6, 2020 (incorporated by reference to Exhibit 10.2 to the registrant’s Quarterly Report on Form 10-Q, File No. 001-39319, filed August 11, 2020).

EX-10.2 Exhibit 10.2 By Electronic Mail July 6, 2020 Matthew Norkunas *** *** RE: Offer of Employment Dear Matthew: We are very excited to offer you the position of Chief Financial Officer where you will play an essential role in building Generation Bio’s foundation and long-term business and scientific success. Below are the terms of employment for your review and execution. If these terms are ac

August 11, 2020 EX-99.1

Generation Bio Reports Business Updates and Second Quarter 2020 Financial Results

EX-99.1 Exhibit 99.1 Generation Bio Reports Business Updates and Second Quarter 2020 Financial Results CAMBRIDGE, MASS., Aug. 11, 2020 — Generation Bio Co. (Nasdaq: GBIO), an innovative genetic medicines company creating a new class of non-viral gene therapy, today reported recent business highlights and second quarter financial results. “The first half of 2020 has seen meaningful progress for Gen

July 24, 2020 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 21, 2020 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81-4301284 (State or Other Jurisdiction of Incorporation) (Commission File N

June 26, 2020 SC 13G

GBIO / Generation Bio Co. / Artal International S.c.a. - SC 13G Passive Investment

SC 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934* (Amendment No. ) Generation Bio Co. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 37148K100 (CUSIP Number) June 16, 2020 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the r

June 26, 2020 SC 13G

GBIO / Generation Bio Co. / Zone Healthcare Holdings, LLC Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

June 26, 2020 EX-99.1

JOINT FILING AGREEMENT

EX-1 EXHIBIT 1 JOINT FILING AGREEMENT The undersigned agree that the statement on Schedule 13G with respect to the common stock, $0.

June 16, 2020 SC 13G

GBIO / Generation Bio Co. / Flynn James E Passive Investment

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1(b)(c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(b) (Amendment No.

June 16, 2020 8-K

Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Financial Statements and Exhibits

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 16, 2020 Generation Bio Co. (Exact Name of Registrant as Specified in Charter) Delaware 001-39319 81- 4301284 (State or Other Jurisdiction of Incorporation) (Commission File

June 16, 2020 EX-3.1

Restated Certificate of Incorporation of the registrant, effective as of June 16, 2020 (incorporated by reference to Exhibit 3.1 to the registrant’s Current Report on Form 8-K, File No. 001-39319, filed June 16, 2020).

EX-3.1 Exhibit 3.1 RESTATED CERTIFICATE OF INCORPORATION OF GENERATION BIO CO. Generation Bio Co., a corporation organized and existing under the General Corporation Law of the State of Delaware, does hereby certify that the name of the corporation is Generation Bio Co. and the original certificate of incorporation of the corporation was filed with the Secretary of State of the State of Delaware o

June 16, 2020 EX-3.2

Bylaws of the registrant, effective as of June 16, 2020 (incorporated by reference to Exhibit 3.2 to the registrant’s Current Report on Form 8-K, File No. 001-39319, filed June 16, 2020).

EX-3.2 Exhibit 3.2 AMENDED AND RESTATED BYLAWS OF GENERATION BIO CO. TABLE OF CONTENTS Page ARTICLE I STOCKHOLDERS 1 1.1 Place of Meetings 1 1.2 Annual Meeting 1 1.3 Special Meetings 1 1.4 Record Date for Stockholder Meetings 1 1.5 Notice of Meetings 2 1.6 Voting List 2 1.7 Quorum 3 1.8 Adjournments 4 1.9 Voting and Proxies 4 1.10 Action at Meeting 4 1.11 Nomination of Directors 5 1.12 Notice of B

June 12, 2020 424B4

Joint bookrunning managers J.P. Morgan Jefferies Cowen Lead manager Wedbush PacGrow

424B4 Table of Contents Filed Pursuant to Rule 424(b)(4) Registration No. 333-238608 Prospectus 10,526,316 shares Common stock This is Generation Bio Co.’s initial public offering. We are selling 10,526,316 shares of our common stock. The public offering price is $19.00 per share. Currently, no public market exists for the shares. The shares will trade on the Nasdaq Global Select Market under the

June 12, 2020 S-8

File No. 333-239116

S-8 As filed with the Securities and Exchange Commission on June 12, 2020 Registration No.

June 11, 2020 S-1MEF

- S-1MEF

S-1MEF As filed with the Securities and Exchange Commission on June 11, 2020 Registration No.

June 11, 2020 S-1/A

- S-1/A

S-1/A Table of Contents As filed with the Securities and Exchange Commission on June 11, 2020 Registration No.

June 9, 2020 CORRESP

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Underwriter acceleration request J.P. Morgan Securities LLC 383 Madison Avenue New York, New York 10179 Jefferies LLC 520 Madison Avenue New York, New York 10022 Cowen and Company, LLC 599 Lexington Avenue New York, New York 10010 June 9, 2020 VIA EDGAR U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, D.C. 20549 Re: Generation Bio Co. Registrat

June 9, 2020 CORRESP

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CORRESP Generation Bio Co. 301 Binney Street Cambridge, MA 02142 June 9, 2020 VIA EDGAR U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, D.C. 20549 Attention: Courtney Lindsay Re: Generation Bio Co. Registration Statement on Form S-1 File No. 333-238608 Request for Acceleration Ladies and Gentlemen: Pursuant to Rule 461 promulgated under the Se

June 8, 2020 EX-1.1

Form of Underwriting Agreement

EX-1.1 Exhibit 1.1 Generation Bio Co. [●] Shares of Common Stock Underwriting Agreement [•], 2020 J.P. Morgan Securities LLC Jefferies LLC Cowen and Company, LLC As Representatives of the several Underwriters listed in Schedule 1 hereto c/o J.P. Morgan Securities LLC 383 Madison Avenue New York, New York 10179 c/o Jefferies LLC 520 Madison Avenue New York, New York 10022 c/o Cowen and Company, LLC

June 8, 2020 8-A12B

Form 8-A

8-A12B UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-A FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 Generation Bio Co. (Exact name of registrant as specified in its charter) Delaware 81-4301284 (State of incorporation or organization) (I.R.S. Employer Identification No.) 301 Binney Street

June 8, 2020 S-1/A

- S-1/A

S-1/A Table of Contents As filed with the Securities and Exchange Commission on June 8, 2020 Registration No.

June 8, 2020 EX-4.1

Specimen Stock Certificate evidencing the shares of common stock (incorporated by reference to Exhibit 4.1 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed June 8, 2020).

EX-4.1 Exhibit 4.1 MR A SAMPLE DESIGNATION (IF ANY) ADD 1 ADD 2 ADD 3 ADD 4 PO BOX 505006, Louisville, KY 40233-5006 CUSIP/IDENTIFIER XXXXXX XX X Holder ID XXXXXXXXXX Insurance Value 1,000,000.00 Number of Shares 123456 DTC 12345678 123456789012345 Certificate Numbers Num/No. Denom. Total 1234567890/1234567890 1 1 1 1234567890/1234567890 2 2 2 1234567890/1234567890 3 3 3 1234567890/1234567890 4 4

June 8, 2020 EX-10.11

Exclusive License Agreement, dated June 28, 2017, by and between the registrant and the University of Massachusetts, as amended

EX-10.11 Exhibit 10.11 Certain identified information has been marked in the exhibit because it is both (i) not material and (ii) would likely cause competitive harm to the Company, if publicly disclosed. Double asterisks denote omissions. EXCLUSIVE LICENSE AGREEMENT This Agreement, effective as of June 23, 2017 (the “Effective Date”), is between the University of Massachusetts (“University”), a n

June 8, 2020 EX-3.5

Certificate of Amendment to the Third Amended and Restated Certificate of Incorporation of the registrant, effective as of June 5, 2020

EX-3.5 Exhibit 3.5 CERTIFICATE OF AMENDMENT TO THE THIRD AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF GENERATION BIO CO. Generation Bio Co. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware (the “General Corporation Law”), does hereby certify as follows: A resolution was duly adopted by the Board of Directo

May 22, 2020 EX-10.3

Form of Restricted Stock Agreement under 2017 Stock Incentive Plan (incorporated by reference to Exhibit 10.3 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.3 Exhibit 10.3 GENERATION BIO CO. RESTRICTED STOCK AGREEMENT GRANTED UNDER 2017 STOCK INCENTIVE PLAN This Restricted Stock Agreement (the “Agreement”) is made this [ ] day of [ ], 20[ ], between Generation Bio Co., a Delaware corporation (the “Company”), and [ ] (the “Recipient”). For valuable consideration, receipt of which is acknowledged, the parties hereto agree as follows: 1. Issuance o

May 22, 2020 EX-10.18

Consulting Agreement, dated September 25, 2019, by and between the registrant and Danforth Advisors, LLC

EX-10.18 Exhibit 10.18 CONSULTING AGREEMENT This Consulting Agreement (the “Agreement”) is made effective as of September 26, 2019 (the “Effective Date”), by and between Generation Bio Co., a Delaware corporation, with its principal place of business being 301 Binney Street, Suite 401, Cambridge, MA 02142 (the “Company”) and Danforth Advisors, LLC, a Massachusetts limited liability corporation, wi

May 22, 2020 EX-10.1

2017 Stock Incentive Plan (incorporated by reference to Exhibit 10.1 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.1 Exhibit 10.1 2017 STOCK INCENTIVE PLAN OF TORUS THERAPEUTICS, INC. TABLE OF CONTENTS PAGE 1. Purpose 1 2. Eligibility 1 3. Administration and Delegation 1 (a) Administration by the Board 1 (b) Appointment of Committees 1 4. Stock Available for Awards 2 (a) Number of Shares 2 (b) Substitute Awards 2 5. Stock Options 2 (a) General 2 (b) Incentive Stock Options 2 (c) Exercise Price. 3 (d) Dur

May 22, 2020 EX-4.2

Second Amended and Restated Investors’ Rights Agreement dated as of January 9, 2020 by and among the registrant and the other parties thereto (incorporated by reference to Exhibit 4.2 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-4.2 Exhibit 4.2 EXECUTION VERSION GENERATION BIO CO. SECOND AMENDED AND RESTATED INVESTORS’ RIGHTS AGREEMENT TABLE OF CONTENTS Page 1. Definitions 1 2. Registration Rights 4 2.1 Demand Registration 4 2.2 Company Registration 6 2.3 Underwriting Requirements 6 2.4 Obligations of the Company 8 2.5 Furnish Information 9 2.6 Expenses of Registration 9 2.7 Delay of Registration 10 2.8 Indemnification

May 22, 2020 EX-10.10

Form of Indemnification Agreement between the registrant and each of its executive officers and directors (incorporated by reference to Exhibit 10.10 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.10 Exhibit 10.10 INDEMNIFICATION AGREEMENT This Indemnification Agreement (“Agreement”) is made as of , 20 by and between Generation Bio Co., a Delaware corporation (the “Company”), and (“Indemnitee”). This Agreement supersedes and replaces any and all previous Agreements between the Company and Indemnitee covering the subject matter of this Agreement. [[Solely with respect to officers and d

May 22, 2020 EX-10.5

Form of Stock Option Agreement under 2020 Stock Incentive Plan (incorporated by reference to Exhibit 10.5 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.5 Exhibit 10.5 Generation Bio Co. STOCK OPTION AGREEMENT Generation Bio Co. (the “Company”) hereby grants the following stock option pursuant to its 2020 Stock Incentive Plan. The terms and conditions attached hereto are also a part hereof. Notice of Grant Name of optionee (the “Participant”): Grant Date: Incentive Stock Option or Nonstatutory Stock Option: Number of shares of the Company’s

May 22, 2020 EX-10.14

Offer letter, dated June 25, 2017, by and between the registrant and Douglas Kerr (incorporated by reference to Exhibit 10.14 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

Exhibit 10.14 Torus Therapeutics, Inc. June 25, 2017 Douglas Kerr Dear Doug: On behalf of Torus Therapeutics (the ?Company?), I am pleased to offer you employment with the Company on the following terms and conditions. 1. Position. You will be employed by the Company as the Chief Scientific Officer and Executive Vice President of Research and Development. It is contemplated that you will commence

May 22, 2020 EX-10.16

Consulting Agreement, dated January 2, 2019, by and between the registrant and Thomas Graney

Exhibit 10.16 GENERATION BIO CO. CONSULTING AGREEMENT This Consulting Agreement (the ?Agreement?), made this 5th day of January, 2019 is entered into by Generation Bio Co., a Delaware corporation (the ?Company?), and Tom Graney, an individual residing at (the ?Consultant?). WHEREAS, the Company and the Consultant desire to establish the terms and conditions under which the Consultant will provide

May 22, 2020 EX-10.12

Public Health Service Patent License Agreement Nonexclusive Sublicensable, dated February 2, 2017, by and between the registrant and the U.S. Department of Health and Human Services, as represented by the National Heart, Lung, and Blood Institute, as amended on June 20, 2019 (incorporated by reference to Exhibit 10.12 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.12 Exhibit 10.12 Certain identified information has been marked in the exhibit because it is both (i) not material and (ii) would likely cause competitive harm to the Company, if publicly disclosed. Double asterisks denote omissions. PUBLIC HEALTH SERVICE PATENT LICENSE AGREEMENT NONEXCLUSIVE SUBLICENSABLE This Agreement is based on the model Patent License Non-Exclusive Sublicensable Agreem

May 22, 2020 EX-21.1

Subsidiaries of the registrant

Exhibit 21.1 Subsidiaries of the Registrant Entity Jurisdiction of Incorporation Generation Bio Securities Corporation Massachusetts

May 22, 2020 EX-3.2

By-laws of the registrant

EX-3.2 Exhibit 3.2 BY-LAWS of TORUS THERAPEUTICS, INC. (the “Corporation”) 1. Stockholders (a) Annual Meeting. The annual meeting of stockholders shall be held for the election of directors each year at such place, date and time as shall be designated by the Board of Directors. Any other proper business may be transacted at the annual meeting. If no date for the annual meeting is established or sa

May 22, 2020 EX-3.3

Form of Certificate of Incorporation of the registrant (to be effective upon the closing of this offering)

EX-3.3 Exhibit 3.3 RESTATED CERTIFICATE OF INCORPORATION OF GENERATION BIO CO. Generation Bio Co., a corporation organized and existing under the General Corporation Law of the State of Delaware, does hereby certify that the name of the corporation is Generation Bio Co. and the original certificate of incorporation of the corporation was filed with the Secretary of State of the State of Delaware o

May 22, 2020 EX-10.4

2020 Stock Incentive Plan (incorporated by reference to Exhibit 10.4 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.4 Exhibit 10.4 Generation Bio Co. 2020 STOCK INCENTIVE PLAN 1. Purpose The purpose of this 2020 Stock Incentive Plan (the “Plan”) of Generation Bio Co., a Delaware corporation (the “Company”), is to advance the interests of the Company’s stockholders by enhancing the Company’s ability to attract, retain and motivate persons who are expected to make important contributions to the Company and

May 22, 2020 EX-10.11

Exclusive License Agreement, dated June 28, 2017, by and between the registrant and the University of Massachusetts, as amended (incorporated by reference to Exhibit 10.11 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

Exhibit 10.11 Certain identified information has been marked in the exhibit because it is both (i) not material and (ii) would likely cause competitive harm to the Company, if publicly disclosed. Double asterisks denote omissions. EXCLUSIVE LICENSE AGREEMENT This Agreement, effective as of June 23, 2017 (the ?Effective Date?), is between the University of Massachusetts (?University?), a not-for-pr

May 22, 2020 EX-10.15

Offer letter, dated December 14, 2018, by and between the registrant and Thomas Graney

Exhibit 10.15 December 14, 2018 Tom Graney RE: Offer of Employment Dear Tom, We are very excited to offer you the position of Chief Financial Officer where you will play an essential role in building Generation Bio?s foundation and long-term business and scientific success. Below are the terms of employment for your review and execution. If these terms are acceptable, please sign and return a copy

May 22, 2020 EX-3.4

Bylaws of the registrant, effective as of June 16, 2020 (incorporated by reference to Exhibit 3.4 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

Exhibit 3.4 AMENDED AND RESTATED BYLAWS OF GENERATION BIO CO. TABLE OF CONTENTS Page ARTICLE I STOCKHOLDERS 1 1.1 Place of Meetings 1 1.2 Annual Meeting 1 1.3 Special Meetings 1 1.4 Record Date for Stockholder Meetings 1 1.5 Notice of Meetings 2 1.6 Voting List 2 1.7 Quorum 3 1.8 Adjournments 4 1.9 Voting and Proxies 4 1.10 Action at Meeting 4 1.11 Nomination of Directors 5 1.12 Notice of Business

May 22, 2020 EX-10.13

Offer letter, dated October 12, 2017, by and between the registrant and Geoff McDonough (incorporated by reference to Exhibit 10.13 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.13 Exhibit 10.13 Torus Therapeutics, Inc. October 12, 2017 Geoffrey McDonough Dear Geoff: On behalf of Torus Therapeutics, Inc. (the “Company”), I am pleased to offer you employment with the Company on the following terms and conditions. 1. Position. You will be employed by the Company as its President and Chief Executive Officer (“CEO”). It is contemplated that you will commence employment

May 22, 2020 CORRESP

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CORRESP Stuart M. Falber +1 617 526 6663 (t) +1 617 526 5000 (f) wilmerhale.com [email protected] May 22, 2020 By Electronic Submission U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, DC 20549 Attention: Courtney Lindsay Re: Generation Bio Co. Amendment 1 to Draft Registration Statement on Form S-1 Submitted May 12, 2020 CIK No. 000

May 22, 2020 EX-10.19

Form of Severance Plan Benefit Agreement by and between the registrant and certain of its executive officers (incorporated by reference to Exhibit 10.19 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.19 Exhibit 10.19 By Electronic Mail [Date] [Name] [Street Address] [City, State ZIP] RE: Severance Plan Benefit Dear [Name]: Generation Bio (the “Company”) is pleased to set forth the severance benefits that you may be eligible to receive upon certain terminations of your employment with the Company (or its successor) under this letter agreement (“Agreement”). All other terms and conditions

May 22, 2020 EX-10.9

Lease, dated August 2, 2018, by and between the registrant and BMR-Rogers Street LLC, as amended

EX-10.9 Exhibit 10.9 LEASE by and between BMR-ROGERS STREET LLC, a Delaware limited liability company and GENERATION BIO CO., a Delaware corporation TABLE OF CONTENTS Page 1. Lease of Premises 1 2. Basic Lease Provisions 2 3. Term 5 4. Possession and Commencement Date 5 5. Condition of Premises 8 6. Rentable Area 8 7. Rent 9 8. Rent Adjustments 10 9. Operating Expenses 10 10. Taxes on Tenant’s Pro

May 22, 2020 S-1

Registration Statement - S-1

S-1 Table of Contents As filed with the Securities and Exchange Commission on May 22, 2020 Registration No.

May 22, 2020 EX-3.1

Third Amended and Restated Certificate of Incorporation of the registrant

EX-3.1 Exhibit 3.1 THIRD AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF GENERATION BIO CO. (Pursuant to Sections 242 and 245 of the General Corporation Law of the State of Delaware) Generation Bio Co., a corporation organized and existing under and by virtue of the provisions of the General Corporation Law of the State of Delaware (the “General Corporation Law”), DOES HEREBY CERTIFY: 1. That

May 22, 2020 EX-10.8

2020 Employee Stock Purchase Plan (incorporated by reference to Exhibit 10.8 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

Exhibit 10.8 Generation Bio Co. 2020 EMPLOYEE STOCK PURCHASE PLAN The purpose of this 2020 Employee Stock Purchase Plan (this ?Plan?) is to provide eligible employees of Generation Bio Co. (the ?Company?) and certain of its subsidiaries with opportunities to purchase shares of the Company?s common stock, $0.0001 par value per share (the ?Common Stock?), commencing at such time and on such dates as

May 22, 2020 EX-10.7

Form of Restricted Stock Unit Agreement under 2020 Stock Incentive Plan (incorporated by reference to Exhibit 10.7 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.7 Exhibit 10.7 Generation Bio Co. RESTRICTED STOCK UNIT AGREEMENT Generation Bio Co. (the “Company”) hereby grants the following restricted stock units pursuant to its 2020 Stock Incentive Plan. The terms and conditions attached hereto are also a part hereof. Notice of Grant Name of recipient (the “Participant”): Grant Date: Number of restricted stock units (“RSUs”) granted: Vesting Start Da

May 22, 2020 EX-10.6

Form of Restricted Stock Agreement under 2020 Stock Incentive Plan (incorporated by reference to Exhibit 10.6 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

EX-10.6 Exhibit 10.6 Generation Bio Co. RESTRICTED STOCK AGREEMENT Generation Bio Co. (the “Company”) hereby grants the following award of restricted stock pursuant to its 2020 Stock Incentive Plan. The terms and conditions attached hereto are also a part hereof. Notice of Grant Name of recipient (the “Participant”): Grant Date: Number of shares of the restricted common stock, $0.0001 par value pe

May 22, 2020 EX-10.2

Form of Stock Option Agreement under 2017 Stock Incentive Plan (incorporated by reference to Exhibit 10.2 to the registrant’s Registration Statement on Form S-1, File No. 333-238608, filed May 22, 2020).

Exhibit 10.2 GENERATION BIO CO. STOCK OPTION AGREEMENT GRANTED UNDER 2017 STOCK INCENTIVE PLAN This Stock Option Agreement (this ?Agreement?) is made between Generation Bio Co., a Delaware corporation (the ?Company?), and the Participant pursuant to the 2017 Stock Incentive Plan (the ?Plan?). NOTICE OF GRANT I. Participant Information Participant: [] Participant Address: [] II. Grant Information G

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