GOSS / Gossamer Bio, Inc. - Depositi SEC, Relazione annuale, dichiarazione di delega

Gossamer Bio, Inc.
US ˙ NasdaqGS ˙ US38341P1021

Statistiche di base
LEI 549300ZOC0N2W6PSFR58
CIK 1728117
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 Gossamer Bio, Inc.
SEC Filings (Chronological Order)
Questa pagina fornisce un elenco completo e cronologico dei depositi SEC, esclusi i documenti di proprietà che forniamo altrove.
August 5, 2025 EX-99.1

Gossamer Bio Announces Second Quarter 2025 Financial Results and Provides Business Update - Topline Results from PROSERA Phase 3 Expected in February 2026 - - First Site Activations for Planned Registrational Phase 3 SERANATA Study in PH-ILD Expected

Exhibit 99.1 Gossamer Bio Announces Second Quarter 2025 Financial Results and Provides Business Update - Topline Results from PROSERA Phase 3 Expected in February 2026 - - First Site Activations for Planned Registrational Phase 3 SERANATA Study in PH-ILD Expected in the Fourth Quarter of 2025 - - Cash, cash equivalents and marketable securities totaled $213 million as of June 30, 2025 - SAN DIEGO—

August 5, 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 5, 2025 GOSSAMER BIO, INC.

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 5, 2025 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

August 5, 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.

June 25, 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): June 25, 2025 GOSSAMER BIO, INC.

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 25, 2025 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

June 16, 2025 EX-99.1

Gossamer Bio Announces Completion of Enrollment in Registrational Phase 3 PROSERA Study for the Treatment of PAH - Enrollment Completed in Ongoing Registrational PROSERA Phase 3 Study in PAH - - Topline Results Announcement from PROSERA Phase 3 Expec

Exhibit 99.1 Gossamer Bio Announces Completion of Enrollment in Registrational Phase 3 PROSERA Study for the Treatment of PAH - Enrollment Completed in Ongoing Registrational PROSERA Phase 3 Study in PAH - - Topline Results Announcement from PROSERA Phase 3 Expected in February 2026 - - Blinded Preliminary Baseline Characteristics Align with Intended Study Population - SAN DIEGO—(BUSINESS WIRE)— J

June 16, 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): June 16, 2025 GOSSAMER BIO, INC.

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, 2025 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

May 15, 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.

May 15, 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 15, 2025 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 15, 2025 EX-99.1

Gossamer Bio Announces First Quarter 2025 Financial Results and Provides Business Update, Including Closure of New Patient Screening in Phase 3 PROSERA Study - Enrollment Completion for Ongoing Registrational PROSERA Phase 3 Study in PAH Expected in

Exhibit 99.1 Gossamer Bio Announces First Quarter 2025 Financial Results and Provides Business Update, Including Closure of New Patient Screening in Phase 3 PROSERA Study - Enrollment Completion for Ongoing Registrational PROSERA Phase 3 Study in PAH Expected in Early June; New Patient Screening Closed - - Topline Results Announcement from PROSERA Phase 3 Expected in February 2026 - - To Date, Bli

April 29, 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. )

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 Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) x Defin

April 29, 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 Registrant x Filed by a Party other than the 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 13, 2025 S-8

As filed with the Securities and Exchange Commission on March 13, 2025

Table of Contents As filed with the Securities and Exchange Commission on March 13, 2025 Registration No.

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 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

March 13, 2025 EX-10.7

Gossamer Bio, Inc. Non-Employee Director Compensation Program.

Exhibit 10.7 GOSSAMER BIO, INC. NON-EMPLOYEE DIRECTOR COMPENSATION PROGRAM Non-employee members of the board of directors (the “Board”) of Gossamer Bio, Inc. (the “Company”) shall receive cash and equity compensation as set forth in this Non-Employee Director Compensation Program (this “Program”). This Program has been adopted under the Company’s 2019 Incentive Award Plan (the “Equity Plan”) and s

March 13, 2025 EX-99.1

Gossamer Bio Announces Fourth Quarter and Full-Year 2024 Financial Results and Provides Business Update - PROSERA Phase 3 in PAH on Track for Topline Data Readout in Fourth Quarter of 2025 - - Registrational Phase 3 in PH-ILD Expected to Commence in

Exhibit 99.1 Gossamer Bio Announces Fourth Quarter and Full-Year 2024 Financial Results and Provides Business Update - PROSERA Phase 3 in PAH on Track for Topline Data Readout in Fourth Quarter of 2025 - - Registrational Phase 3 in PH-ILD Expected to Commence in Second Half of 2025 - - Seralutinib Receives Orphan Drug Designation for PAH in Japan - - Cash, cash equivalents and marketable securitie

March 13, 2025 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 ☐ TRANSITION REPORT PURSUANT TO SECTI

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ 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 Commission file number: 001-38796 GOSSAMER BIO, INC. (Exact name of Registrant as specified i

March 13, 2025 EX-19.1

Gossamer Bio, Inc. Insider Trading Compliance Policy and Procedures

Exhibit 19.1 Gossamer Bio, Inc. Insider Trading Compliance Policy and Procedures Federal and state laws prohibit trading in the securities of a company while in possession of material nonpublic information and in breach of a duty of trust or confidence. These laws also prohibit anyone who is aware of material nonpublic information from providing this information to others who may trade. Violating

March 13, 2025 EX-21.1

List of Subsidiaries of the Registrant.

Exhibit 21.1 List of Subsidiaries of Gossamer Bio, Inc. Name Jurisdiction of Incorporation or Organization GB002, LTD. Ireland Gossamer Bio Services, Inc. Delaware

March 13, 2025 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Gossamer Bio, Inc.

February 19, 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): February 19, 2025 GOSSAMER BIO, I

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 19, 2025 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fi

November 12, 2024 SC 13G/A

GOSS / Gossamer Bio, Inc. / Invus Global Management, LLC - SC 13G/A Passive Investment

SC 13G/A 1 d910514dsc13ga.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. 2) Gossamer Bio, Inc. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) September 30, 2024 (Date of Event Which Requires Filing of this Statement) Check

November 12, 2024 EX-99.1

JOINT FILING AGREEMENT

EX-99.1 2 d910514dex991.htm EX-99.1 EXHIBIT 1 JOINT FILING AGREEMENT The undersigned agree that the statement on Schedule 13G with respect to the securities of Gossamer Bio, Inc. is, and any amendments thereto signed by each or any of the undersigned shall be, filed on behalf of each of such person pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act

November 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): November 7, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

November 7, 2024 EX-99.1

Gossamer Bio Announces Third Quarter 2024 Financial Results and Provides Business Update - $327 Million in Cash, Cash Equivalents & Marketable Securities, as of September 30, 2024 -

Exhibit 99.1 Gossamer Bio Announces Third Quarter 2024 Financial Results and Provides Business Update - $327 Million in Cash, Cash Equivalents & Marketable Securities, as of September 30, 2024 - SAN DIEGO—(BUSINESS WIRE)— November 7, 2024 — Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment

November 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.

September 13, 2024 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): September 11, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission F

August 12, 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.

August 12, 2024 EX-99.1

Gossamer Bio Announces Second Quarter 2024 Financial Results and Provides Business Update - $354 Million in Cash, Cash Equivalents & Marketable Securities, as of June 30, 2024 -

Exhibit 99.1 Gossamer Bio Announces Second Quarter 2024 Financial Results and Provides Business Update - $354 Million in Cash, Cash Equivalents & Marketable Securities, as of June 30, 2024 - SAN DIEGO—(BUSINESS WIRE)— August 12, 2024 — Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of p

August 12, 2024 EX-10.1

Collaboration and License Agreement dated May 3, 2024 by and among GB002, Inc., Gossamer Bio 002 Ltd. and Gossamer Bio, Inc. on the one hand and CHIESI Farmaceutici S.p.A and CHIESI USA, Inc. on the other hand.

Exhibit 10.1 CERTAIN INFORMATION CONTAINED IN THIS EXHIBIT, MARKED BY [***], HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE THE REGISTRANT HAS DETERMINED THAT IT IS BOTH NOT MATERIAL AND IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. COLLABORATION AND LICENSE AGREEMENT by and between GB002, INC., GOSSAMER BIO 002 LTD. and GOSSAMER BIO, INC. and CHIESI FARMACEUTICI S.P.A and CHIESI

August 12, 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): August 12, 2024 GOSSAMER BIO, INC

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, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

August 2, 2024 SC 13G/A

GOSS / Gossamer Bio, Inc. / Invus Global Management, LLC - SC 13G/A Passive Investment

SC 13G/A 1 d791379dsc13ga.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. 1) Gossamer Bio, Inc. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) July 25, 2024 (Date of Event Which Requires Filing of this Statement) Check the a

August 2, 2024 EX-99.1

JOINT FILING AGREEMENT

EX-99.1 2 d791379dex991.htm EX-99.1 EXHIBIT 1 JOINT FILING AGREEMENT The undersigned agree that the statement on Schedule 13G with respect to the securities of Gossamer Bio, Inc. is, and any amendments thereto signed by each or any of the undersigned shall be, filed on behalf of each of such person pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act

July 18, 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): July 18, 2024 GOSSAMER BIO, INC.

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, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

June 10, 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 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 24, 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): May 22, 2024 GOSSAMER BIO, INC. (

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 22, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 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.

May 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): May 7, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Num

May 7, 2024 EX-99.1

Gossamer Bio Announces First Quarter 2024 Financial Results and Provides Business Update - Transformative Development and Co-Commercialization Collaboration with Chiesi - - Ongoing PROSERA Phase 3 Study in PAH Expected to Readout in Q4 2025 - - Regis

Exhibit 99.1 Gossamer Bio Announces First Quarter 2024 Financial Results and Provides Business Update - Transformative Development and Co-Commercialization Collaboration with Chiesi - - Ongoing PROSERA Phase 3 Study in PAH Expected to Readout in Q4 2025 - - Registrational Phase 3 in PH-ILD Expected to Commence in Mid-2025 - - TORREY Phase 2 PAH Results Published in Lancet Respiratory Medicine - -

May 6, 2024 8-K

Entry into a Material Definitive Agreement, Termination of a Material Definitive Agreement, Unregistered Sales of Equity Securities, 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): May 3, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Num

May 6, 2024 EX-99.1

Gossamer Bio and Chiesi Group Announce Transformative Global Collaboration to Develop and Commercialize Seralutinib in PAH, PH-ILD & Other Indications - Gossamer to receive $160 million development reimbursement payment and eligible to receive up to

Exhibit 99.1 Gossamer Bio and Chiesi Group Announce Transformative Global Collaboration to Develop and Commercialize Seralutinib in PAH, PH-ILD & Other Indications - Gossamer to receive $160 million development reimbursement payment and eligible to receive up to $146 million in regulatory and $180 million in sales milestones - - Gossamer leading US commercialization activities in PAH and PH-ILD; 5

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 Registrant x Filed by a Party other than the 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 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. )

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 Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) x Defin

March 12, 2024 EX-99.1

Gossamer Bio Announces Appointment of Steven D. Nathan, M.D., and Skye Drynan to its Board of Directors

Gossamer Bio Announces Appointment of Steven D. Nathan, M.D., and Skye Drynan to its Board of Directors SAN DIEGO — (BUSINESS WIRE) — March 12, 2024 — Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with inter

March 12, 2024 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): March 11, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

March 5, 2024 EX-10.15

Employment Letter, dated November 25, 2023, by and between Robert Smith and the Registrant.

Exhibit 10.15 Gossamer Bio Services, Inc. 3013 Science Park Road San Diego, CA 92112 November 25, 2023 Robert Smith 30211 Fairway Ash Fair Oaks Ranch, Texas 78015 Dear Bob: This letter agreement (this “Agreement”) confirms the terms of your employment with Gossamer Bio Services, Inc. (the “Company”), a wholly-owned subsidiary of Gossamer Bio, Inc. (the “Parent”). This Agreement is effective as of

March 5, 2024 S-8

As filed with the Securities and Exchange Commission on March 5, 2024

Table of Contents As filed with the Securities and Exchange Commission on March 5, 2024 Registration No.

March 5, 2024 EX-10.7

Gossamer Bio, Inc. Non-Employee Director Compensation Program.

Exhibit 10.7 GOSSAMER BIO, INC. NON-EMPLOYEE DIRECTOR COMPENSATION PROGRAM Non-employee members of the board of directors (the “Board”) of Gossamer Bio, Inc. (the “Company”) shall receive cash and equity compensation as set forth in this Non-Employee Director Compensation Program (this “Program”). This Program has been adopted under the Company’s 2019 Incentive Award Plan (the “Equity Plan”) and s

March 5, 2024 EX-99.1

Gossamer Bio Announces Fourth Quarter and Full-Year 2023 Financial Results and Provides Business Update - First PAH Patient Dosed in Ongoing Registrational Phase 3 PROSERA Study - - Inclusion of Japan in Phase 3 PROSERA Study Following CTN Acceptance

Exhibit 99.1 Gossamer Bio Announces Fourth Quarter and Full-Year 2023 Financial Results and Provides Business Update - First PAH Patient Dosed in Ongoing Registrational Phase 3 PROSERA Study - - Inclusion of Japan in Phase 3 PROSERA Study Following CTN Acceptance by PMDA - - Cash, cash equivalents and marketable securities totaled $296 million at year-end 2023 - SAN DIEGO — (BUSINESS WIRE) — March

March 5, 2024 EX-97

Policy for Recovery of Erroneously Awarded Compensation

Exhibit 97 GOSSAMER BIO, INC. POLICY FOR RECOVERY OF ERRONEOUSLY AWARDED COMPENSATION Gossamer Bio, Inc. (the “Company”) has adopted this Policy for Recovery of Erroneously Awarded Compensation (the “Policy”), effective as of November 30, 2023 (the “Effective Date”). Capitalized terms used in this Policy but not otherwise defined herein are defined in Section 11. 1.Persons Subject to Policy This P

March 5, 2024 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 ☐ TRANSITION REPORT PURSUANT TO SECTI

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ 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 Commission file number: 001-38796 GOSSAMER BIO, INC. (Exact name of Registrant as specified i

March 5, 2024 EX-21.1

List of Subsidiaries of the Registrant.

Exhibit 21.1 List of Subsidiaries of Gossamer Bio, Inc. Name Jurisdiction of Incorporation or Organization GB002, Inc. Delaware Gossamer Bio Services, Inc. Delaware

March 5, 2024 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Gossamer Bio, Inc.

March 5, 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 5, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

March 4, 2024 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): March 4, 2024 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

February 14, 2024 SC 13G/A

GOSS / Gossamer Bio, Inc. / HILLHOUSE CAPITAL MANAGEMENT, LTD. - GOSSAMER BIO, INC. Passive Investment

SC 13G/A 1 p24-0572sc13ga.htm GOSSAMER BIO, INC. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 3)* Gossamer Bio, Inc. (Name of Issuer) Common Stock, par value of $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) December 31, 2023 (Date of Event Which Requires Filing of This Statement) Check

February 13, 2024 SC 13G/A

GOSS / Gossamer Bio, Inc. / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SC 13G/A 1 tv01037-gossamerbioinc.htm SCHEDULE 13G/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 4)* Name of issuer: Gossamer Bio Inc Title of Class of Securities: Common Stock CUSIP Number: 38341P102 Date of Event Which Requires Filing of this Statement: December 29, 2023 Check the appropriate box to designate th

February 9, 2024 SC 13G/A

GOSS / Gossamer Bio, Inc. / ARCH Venture Fund IX, L.P. - ARCH VENTURE FUND IX, L.P. - GOSSAMER BIO -- SCH 13G/A(#1-EXIT) Passive Investment

SC 13G/A 1 arch-sch13g18793.htm ARCH VENTURE FUND IX, L.P. - GOSSAMER BIO - SCH 13G/A(#1-EXIT) UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1 – Exit Filing)* Gossamer Bio, Inc. (Name of Issuer) Common Stock par value $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) July 24, 202

January 11, 2024 SC 13G/A

GOSS / Gossamer Bio, Inc. / MILLENNIUM MANAGEMENT LLC Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (AMENDMENT NO. 1) GOSSAMER BIO, INC. (Name of Issuer) COMMON STOCK, PAR VALUE $0.0001 PER SHARE (Title of Class of Securities) 38341P102 (CUSIP Number) DECEMBER 31, 2023 (Date of event which requires filing of this statement) Check the appropriate box to designate the rule

January 11, 2024 EX-99.1

JOINT FILING AGREEMENT

EX-99.1 2 d723472dex991.htm EX-99.1 EXHIBIT 1 JOINT FILING AGREEMENT The undersigned agree that the statement on Schedule 13G with respect to the Common Stock, $0.0001 par value per share, of Gossamer Bio, Inc. is, and any amendments thereto signed by each of the undersigned shall be, filed on behalf of each of them pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Secur

January 11, 2024 SC 13G

GOSS / Gossamer Bio, Inc. / 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.) Gossamer Bio, Inc. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) December 14, 2023 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate th

November 29, 2023 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): November 28, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fi

November 29, 2023 EX-99.1

Gossamer Bio Announces Appointment of John Quisel, J.D., Ph.D., to its Board of Directors

Gossamer Bio Announces Appointment of John Quisel, J.D., Ph.D., to its Board of Directors SAN DIEGO — (BUSINESS WIRE) — November 29, 2023 — Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension (PAH), today announced the appointment of John Quisel, J.D., Ph.D

November 27, 2023 EX-3.1

Amended and Restated Bylaws

AMENDED AND RESTATED BYLAWS OF GOSSAMER BIO, INC. (a Delaware corporation) TABLE OF CONTENTS Page Article I CORPORATE OFFICES 1 1.1 REGISTERED OFFICE. 1 1.2 OTHER OFFICES. 1 Article II MEETINGS OF STOCKHOLDERS 1 2.1 PLACE OF MEETINGS 1 2.2 ANNUAL MEETING 1 2.3 SPECIAL MEETING 1 2.4 ADVANCE NOTICE PROCEDURES FOR BUSINESS BROUGHT BEFORE A MEETING 2 2.5 ADVANCE NOTICE PROCEDURES FOR NOMINATIONS OF DI

November 27, 2023 EX-10.1

Gossamer Bio, Inc. 2023 Employment Inducement Incentive Award Plan and Form of Stock Option Agreement thereunder.

GOSSAMER BIO, INC. 2023 EMPLOYMENT INDUCEMENT INCENTIVE AWARD PLAN ARTICLE I. PURPOSE The Plan’s purpose is to enhance the Company’s ability to attract, retain and motivate Eligible Individuals who are expected to make important contributions to the Company by providing these individuals with equity ownership opportunities. Capitalized terms used in the Plan are defined in Article XI. ARTICLE II.

November 27, 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 20, 2023 GOSSAMER BIO, I

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 20, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fi

November 9, 2023 EX-99.1

Gossamer Bio Announces Third Quarter 2023 Financial Results and Provides Business Update - Phase 3 PROSERA Site Activations Proceeding Ahead of Schedule; First Dosing Expected in 4Q23 - - Additional Data from TORREY Open-Label Extension Expected in 4

Exhibit 99.1 Gossamer Bio Announces Third Quarter 2023 Financial Results and Provides Business Update - Phase 3 PROSERA Site Activations Proceeding Ahead of Schedule; First Dosing Expected in 4Q23 - - Additional Data from TORREY Open-Label Extension Expected in 4Q23 - - $329 Million in Cash, Cash Equivalents & Marketable Securities, as of September 30, 2023 - SAN DIEGO—(BUSINESS WIRE)— November 9,

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 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

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.

October 20, 2023 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): October 19, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

September 7, 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): September 6, 2023 GOSSAMER BIO, I

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 6, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fi

August 28, 2023 424B3

162,336,800 Shares of Common Stock

Table of Contents As filed Pursuant to Rule 424(b)(3) Registration No. 333-274056 PROSPECTUS 162,336,800 Shares of Common Stock This prospectus relates to the proposed resale or other disposition by the selling securityholders identified in this prospectus of up to (i) 129,869,440 shares of our common stock, par value $0.0001 per share and (ii) up to 32,467,360 shares of common stock issuable upon

August 24, 2023 CORRESP

Gossamer Bio, Inc. 3013 Science Park Road San Diego, CA 92121

Gossamer Bio, Inc. 3013 Science Park Road San Diego, CA 92121 August 24, 2023 VIA EDGAR U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, D.C. 20549 Re: Gossamer Bio, Inc. Registration Statement on Form S-3 File No. 333-274056 To the addressees set forth above: Pursuant to Rule 461 of Regulation C of the General Rules and Regulations under the S

August 21, 2023 DEL AM

GOSSAMER BIO, INC. 3013 SCIENCE PARK ROAD SAN DIEGO, CA 92121

GOSSAMER BIO, INC. 3013 SCIENCE PARK ROAD SAN DIEGO, CA 92121 August 21, 2023 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, DC 20549 Re: Delaying Amendment for Gossamer Bio, Inc. Registration Statement on Form S-3 (File No. 333-274056) Ladies and Gentlemen: Reference is made to the Registration Statement on Form S-3 (File

August 18, 2023 S-3

As filed with the Securities and Exchange Commission on August 18, 2023

Table of Contents As filed with the Securities and Exchange Commission on August 18, 2023 Registration No.

August 18, 2023 RW

GOSSAMER BIO, INC. 3013 SCIENCE PARK ROAD SAN DIEGO, CA 92121

GOSSAMER BIO, INC. 3013 SCIENCE PARK ROAD SAN DIEGO, CA 92121 August 18, 2023 VIA EDGAR U.S. Securities and Exchange Commission Division of Corporate Finance 100 F Street, N.E. Washington, D.C. 20549 Re: Gossamer Bio, Inc. – Application for Withdrawal of Registration Statement on Form S-3ASR (File No. 333-274045) To Whom It May Concern: Gossamer Bio, Inc. (the “Company” or “Gossamer”) hereby reque

August 18, 2023 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Table Form S-3 (Form Type) Gossamer Bio, Inc.

August 17, 2023 S-3ASR

As filed with the Securities and Exchange Commission on August 17, 2023

Table of Contents As filed with the Securities and Exchange Commission on August 17, 2023 Registration No.

August 17, 2023 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) Gossamer Bio, Inc.

August 8, 2023 EX-10.1

Form of Option Repricing and Cancellation Agreement

Exhibit 10.1 Stock Option Cancellation Agreement and Amendment to Option Agreement(s) This Stock Option Cancellation Agreement and Amendment to Option Agreement(s) (the “Amendment”) is made and entered into effective as of May 5, 2023 (the “Amendment Date”) by and between Gossamer Bio, Inc. (“Gossamer”) and (“Optionee”). Pursuant to this Amendment, Gossamer and Optionee hereby agree to amend the s

August 8, 2023 EX-99.1

Gossamer Bio Announces Second Quarter 2023 Financial Results and Provides Business Update - Seralutinib Phase 3 PROSERA Study in PAH Patients Expected to Initiate in 3Q23 - - Additional Data from TORREY Open-Label Extension Expected in 4Q23 or 1Q24 -

Exhibit 99.1 Gossamer Bio Announces Second Quarter 2023 Financial Results and Provides Business Update - Seralutinib Phase 3 PROSERA Study in PAH Patients Expected to Initiate in 3Q23 - - Additional Data from TORREY Open-Label Extension Expected in 4Q23 or 1Q24 - - $374 Million in Cash, Cash Equivalents & Marketable Securities, as of June 30, 2023, Pro Forma for Gross Proceeds of $212 Million from

August 8, 2023 EX-3.1

Amended and Restated Certificate of Incorporation, as amended.

Exhibit 3.1 AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF GOSSAMER BIO, INC. (originally incorporated on October 26, 2015 under the name FSG Bio,Inc.) FIRST: The name of the Corporation is Gossamer Bio, Inc. SECOND: The address of the Corporation's registered office in the State of Delaware is 251 Little Falls Drive, City of Wilmington, County of New Castle, State of Delaware 19808. The nam

August 8, 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.

August 8, 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 8, 2023 GOSSAMER BIO, INC.

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 8, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

July 28, 2023 SC 13D

GOSS / Gossamer Bio Inc / Growth Equity Opportunities 18 VGE, LLC - GROWTH EQUITY OPPORTUNITIES 18 VGE, LLC / GOSSAMER BIO, INC. -- SCHEDULE 13D Activist Investment

Schedule 13D UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. )* Gossamer Bio, Inc. (Name of Issuer) Common Stock, $0.0001 par value (Title of Class of Securities) 38341P102 (CUSIP Number) Louis S. Citron, Esq. New Enterprise Associates 1954 Greenspring Drive, Suite 600, Timonium, MD 21093 (410) 842-4000 (

July 20, 2023 EX-4.1

Form of Warrant

Exhibit 4.1 THE OFFER AND SALE OF THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”). THE HOLDER MAY NOT OFFER, SELL, TRANSFER, ASSIGN, PLEDGE, HYPOTHECATE, OR OTHERWISE DISPOSE OF OR ENCUMBER SUCH SECURITIES EXCEPT (I) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT AND THE RULES AND REGULATIONS P

July 20, 2023 EX-99.1

Interim TORREY OLE Update and PROSERA Phase 3 Design July 2023 Forward Looking Statements This presentation contains forward-looking statements. All statements other than statements of historical facts contained in this presentation, including statem

goss-oleupdate8xkx202307 Interim TORREY OLE Update and PROSERA Phase 3 Design July 2023 Forward Looking Statements This presentation contains forward-looking statements.

July 20, 2023 EX-10.1

Form of Securities Purchase Agreement.

Exhibit 10.1 GOSSAMER BIO, INC. SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (the “Agreement”) is made as of July 19, 2023 (the “Effective Date”), by and among Gossamer Bio, Inc., a Delaware corporation (the “Company”), and the purchasers whose names and addresses are set forth on the signature pages hereof (each, a “Purchaser” and, collectively, the “Purchasers”). Whereas, the

July 20, 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): July 20, 2023 GOSSAMER BIO, INC.

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 20, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

July 20, 2023 EX-99.1

Gossamer Bio Announces $212 Million Private Placement Financing - In Conjunction with Offering, Interim TORREY OLE Data and PROSERA Phase 3 Design Disclosed via 8-K; Conference Call to Discuss Data and Phase 3 Design with Leading PAH KOLs to be Held

Exhibit 99.1 Gossamer Bio Announces $212 Million Private Placement Financing - In Conjunction with Offering, Interim TORREY OLE Data and PROSERA Phase 3 Design Disclosed via 8-K; Conference Call to Discuss Data and Phase 3 Design with Leading PAH KOLs to be Held on July 25th - SAN DIEGO – July 20, 2023 – Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on the d

July 20, 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): July 19, 2023 GOSSAMER BIO, INC.

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 19, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

June 9, 2023 EX-3.1

Certificate of Amendment to Amended and Restated Certificate of Incorporation, dated June 8, 2023

goss-charteramendmentjun CERTIFICATE OF AMENDMENT OF AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF GOSSAMER BIO, INC.

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 GOSSAMER BIO, INC. (

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 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 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): May 9, 2023 GOSSAMER BIO, INC. (E

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 9, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Num

May 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 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: 001-38796 G

May 9, 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 Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ¨ Defin

May 9, 2023 EX-99.1

Gossamer Bio Announces First Quarter 2023 Financial Results and Provides Business Update - Feedback on Planned Registrational Program for Seralutinib Received from FDA and EMA following Successful Phase 2 TORREY Study - - Registrational Phase 3 Clini

Exhibit 99.1 Gossamer Bio Announces First Quarter 2023 Financial Results and Provides Business Update - Feedback on Planned Registrational Program for Seralutinib Received from FDA and EMA following Successful Phase 2 TORREY Study - - Registrational Phase 3 Clinical Trial in PAH Patients Expected to Initiate in 3Q23 - - Initial TORREY Study Open-Label Extension Data Expected Mid 2023 - - Operation

April 28, 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 Registrant x Filed by a Party other than the 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 28, 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. )

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 Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) x Defin

April 17, 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. )

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 Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: x Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ¨ Defin

April 3, 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): April 3, 2023 GOSSAMER BIO, INC.

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): April 3, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

March 17, 2023 EX-21.1

List of Subsidiaries of the Registrant.

Exhibit 21.1 List of Subsidiaries of Gossamer Bio, Inc. Name Jurisdiction of Incorporation or Organization GB002, Inc. Delaware GB005, Inc. Delaware Gossamer Bio Services, Inc. Delaware

March 17, 2023 EX-10.24

Fourth Amendment to Credit, Guarantee and Security Agreement, dated February 14, 2023, by and among the Registrant, GB001, Inc., GB002, Inc. and GB004, Inc., as co-borrowers, the other guarantors from time to time party thereto and MidCap Financial Trust, as Agent and as a Lender and the additional lenders from time to time party thereto.

Exhibit 10.24 Execution Version CONSENT AND RELEASE This CONSENT AND RELEASE (this “Agreement”) is made as of this 14 day of February, 2023 (“Effective Date”), by and among GB001, INC., a Delaware corporation (“GB001”), GOSSAMER BIO, INC., Delaware corporation (“Parent”), GB002, INC., a Delaware corporation (“GB002”), GB004, INC., a Delaware corporation (“GB004” and GB004 together with Parent, GB0

March 17, 2023 EX-10.7

Gossamer Bio, Inc. Non-Employee Director Compensation Program.

Exhibit 10.7 GOSSAMER BIO, INC. NON-EMPLOYEE DIRECTOR COMPENSATION PROGRAM Non-employee members of the board of directors (the “Board”) of Gossamer Bio, Inc. (the “Company”) shall receive cash and equity compensation as set forth in this Non-Employee Director Compensation Program (this “Program”). This Program has been adopted under the Company’s 2019 Incentive Award Plan (the “Equity Plan”) and s

March 17, 2023 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 ☐ TRANSITION REPORT PURSUANT TO SECTI

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ 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 Commission file number: 001-38796 GOSSAMER BIO, INC. (Exact name of Registrant as specified i

March 17, 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 17, 2023 GOSSAMER BIO, INC.

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 17, 2023 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

March 17, 2023 EX-10.23

and Security Agreement, dated December 7, 2022, by and among the Registrant, GB001, Inc., GB002, Inc. and GB004, Inc., as co-borrowers, the other guarantors from time to time party thereto and MidCap Financial Trust, as Agent and as a Lender and the additional lenders from time to time party thereto.

Exhibit 10.23 Execution Version THIRD AMENDMENT TO CREDIT, GUARANTY AND SECURITY AGREEMENT This THIRD AMENDMENT TO CREDIT, GUARANTY AND SECURITY AGREEMENT (this “Agreement”) is made as of this 7th day of December, 2022 (“Effective Date”), by and among GB001, INC., a Delaware corporation (“GB001”), GOSSAMER BIO, INC., Delaware corporation (“Parent”), GB002, INC., a Delaware corporation (“GB002”), G

March 17, 2023 EX-99.1

Gossamer Bio Announces Fourth Quarter and Full-Year 2022 Financial Results and Provides Business Update - FDA Feedback on Seralutinib Phase 3 Clinical Trial Received; Expected to Commence in the Second Half of 2023 - - Topline Data from TORREY Study

Exhibit 99.1 Gossamer Bio Announces Fourth Quarter and Full-Year 2022 Financial Results and Provides Business Update - FDA Feedback on Seralutinib Phase 3 Clinical Trial Received; Expected to Commence in the Second Half of 2023 - - Topline Data from TORREY Study Open-Label Extension Expected in Mid-2023 - - Enrollment in GB5121 Phase 1b/2 Clinical Trial in PCNSL Paused - - Cash, cash equivalents a

February 14, 2023 SC 13G/A

GOSS / Gossamer Bio Inc / HILLHOUSE CAPITAL ADVISORS, LTD. - GOSSAMER BIO, INC. Passive Investment

SC 13G/A 1 p23-0182sc13ga.htm GOSSAMER BIO, INC. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 2)* Gossamer Bio, Inc. (Name of Issuer) Common Stock, par value of $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) December 31, 2022 (Date of Event Which Requires Filing of This Statement) Check

February 9, 2023 SC 13G/A

GOSS / Gossamer Bio Inc / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

January 10, 2023 SC 13G

GOSS / Gossamer Bio Inc / STATE STREET CORP Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G UNDER THE SECURITIES EXCHANGE ACT OF 1934 INITIAL FILING GOSSAMER BIO INC (NAME OF ISSUER) COMMON STOCK (TITLE OF CLASS OF SECURITIES) 38341P102 (CUSIP NUMBER) 12/31/2022 (DATE OF EVENT WHICH REQUIRES FILING OF THIS STATEMENT) CHECK THE APPROPRIATE BOX TO DESIGNATE THE RULE PURSUANT TO WHICH THIS SCHEDULE IS FILED

January 4, 2023 SC 13G

GOSS / Gossamer Bio Inc / MILLENNIUM MANAGEMENT LLC Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 GOSSAMER BIO, INC. (Name of Issuer) COMMON STOCK, PAR VALUE $0.0001 PER SHARE (Title of Class of Securities) 38341P102 (CUSIP Number) DECEMBER 29, 2022 (Date of event which requires filing of this statement) Check the appropriate box to designate the rule pursuant to which

December 20, 2022 SC 13G

GOSS / Gossamer Bio Inc / MILLENNIUM MANAGEMENT LLC Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 GOSSAMER BIO, INC. (Name of Issuer) COMMON STOCK, PAR VALUE $0.0001 PER SHARE (Title of Class of Securities) 38341P102 (CUSIP Number) DECEMBER 12, 2022 (Date of event which requires filing of this statement) Check the appropriate box to designate the rule pursuant to which

December 6, 2022 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): December 6, 2022 GOSSAMER BIO, IN

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 6, 2022 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

December 6, 2022 EX-99.1

Phase 2 TORREY Study Topline Results 1 December 6, 2022 Exhibit 99.1 Forward Looking Statements This presentation contains forward-looking statements. All statements other than statements of historical facts contained in this presentation, including

gb002-2101torreytopliner Phase 2 TORREY Study Topline Results 1 December 6, 2022 Exhibit 99.

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 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

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.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, 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: 001-387

November 3, 2022 EX-99.1

Gossamer Bio Announces Third Quarter 2022 Financial Results and Provides Business Update - Seralutinib Phase 2 TORREY Study on track for topline readout in second half of November or first half of December - - $304 million in cash, cash equivalents &

Exhibit 99.1 Gossamer Bio Announces Third Quarter 2022 Financial Results and Provides Business Update - Seralutinib Phase 2 TORREY Study on track for topline readout in second half of November or first half of December - - $304 million in cash, cash equivalents & marketable securities, as of September 30, 2022 SAN DIEGO?(BUSINESS WIRE)? November 3, 2022 ? Gossamer Bio, Inc. (Nasdaq: GOSS), a clini

August 9, 2022 EX-99.1

Gossamer Bio Announces Second Quarter 2022 Financial Results and Provides Business Update - Seralutinib Phase 2 TORREY Study on track for topline readout in second half of November or first half of December - - CNS-penetrant GB5121 doses first patien

Exhibit 99.1 Gossamer Bio Announces Second Quarter 2022 Financial Results and Provides Business Update - Seralutinib Phase 2 TORREY Study on track for topline readout in second half of November or first half of December - - CNS-penetrant GB5121 doses first patient in Phase 1b/2 STAR CNS Study in PCNSL and other rare CNS malignancies - - $342 million in cash, cash equivalents & marketable securitie

August 9, 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 June 30, 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: 001-38796 GO

August 9, 2022 EX-10.1

Second Amendment to Sublease Agreement, dated June 1, 2022, by and between the Medicines Company and the Registrant.

EXHIBIT 10.1 SECOND AMENDMENT TO SUBLEASE THIS SECOND AMENDMENT TO SUBLEASE ("Amendment 2") is made and entered into as of the 1st day of June, 2022, by and between THE MEDICINES COMPANY, a Delaware corporation ("Sublessor"), and GOSSAMER BIO, INC., a Delaware corporation ("Sublessee"). R E C I T A L S : A.Sublessor and Sublessee entered into that certain Sublease dated as of December 29, 2017 (th

August 9, 2022 S-3ASR

As filed with the Securities and Exchange Commission on August 9, 2022

Table of Contents As filed with the Securities and Exchange Commission on August 9, 2022 Registration No.

August 9, 2022 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) Gossamer Bio, Inc.

August 9, 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 9, 2022 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

July 13, 2022 EX-99.1

Gossamer Bio Announces $120 million Private Placement Financing

Exhibit 99.1 Gossamer Bio Announces $120 million Private Placement Financing SAN DIEGO ? July 13, 2022 ? Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutics in the disease areas of immunology, inflammation and oncology, announced today it has agreed to sell approximately 16.6 million shares of

July 13, 2022 EX-10.1

Stock Purchase Agreement, dated July 12, 2022, by and among the Registrant and the Purchasers named therein.

Exhibit 10.1 GOSSAMER BIO, INC. STOCK PURCHASE AGREEMENT This Stock Purchase Agreement (the ?Agreement?) is made as of July 12, 2022 (the ?Effective Date?), by and among Gossamer Bio, Inc., a Delaware corporation (the ?Company?), and the purchasers whose names and addresses are set forth on the signature pages hereof (each, a ?Purchaser? and, collectively, the ?Purchasers?). Whereas, in furtheranc

July 13, 2022 8-K

Regulation FD Disclosure, Entry into a Material Definitive Agreement, Unregistered Sales of Equity Securities, 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, 2022 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

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 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 10, 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 10, 2022 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 10, 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: 001-38796 G

May 10, 2022 EX-99.1

Gossamer Bio Announces First Quarter 2022 Financial Results and Provides Business Update - Seralutinib (GB002) completed PAH patient enrollment in Phase 2 TORREY Study - - Topline results from Phase 2 TORREY Study expected in the fourth quarter of 20

Exhibit 99.1 Gossamer Bio Announces First Quarter 2022 Financial Results and Provides Business Update - Seralutinib (GB002) completed PAH patient enrollment in Phase 2 TORREY Study - - Topline results from Phase 2 TORREY Study expected in the fourth quarter of 2022 - - Cash, cash equivalents & marketable securities totaled $272 million as of March 31, 2022 - SAN DIEGO?(BUSINESS WIRE)? May 10, 2022

April 27, 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. )

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 Registrant x Filed by a Party other than the 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 27, 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. )

DEF 14A 1 goss-2022xdef14a.htm 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. ) Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as

April 25, 2022 8-K

Results of Operations and Financial Condition, 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): April 25, 2022 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

March 3, 2022 EX-10.7

Gossamer Bio, Inc. Non-Employee Director Compensation Program.

Exhibit 10.7 GOSSAMER BIO, INC. NON-EMPLOYEE DIRECTOR COMPENSATION PROGRAM Non-employee members of the board of directors (the ?Board?) of Gossamer Bio, Inc. (the ?Company?) shall receive cash and equity compensation as set forth in this Non-Employee Director Compensation Program (this ?Program?). This Program has been adopted under the Company?s 2019 Incentive Award Plan (the ?Equity Plan?) and s

March 3, 2022 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 ☐ TRANSITION REPORT PURSUANT TO SECTI

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission file number: 001-38796 GOSSAMER BIO, INC. (Exact name of Registrant as specified i

March 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): March 3, 2022 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

March 3, 2022 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Gossamer Bio, Inc.

March 3, 2022 S-3ASR

As filed with the Securities and Exchange Commission on March 3, 2022

Table of Contents As filed with the Securities and Exchange Commission on March 3, 2022 Registration No.

March 3, 2022 EX-4.4

Form of Indenture

GOSSAMER BIO, INC. INDENTURE Dated as of , 20 [] Trustee TABLE OF CONTENTS Page ARTICLE I. DEFINITIONS AND INCORPORATION BY REFERENCE 1 Section 1.1. Definitions. 1 Section 1.2. Other Definitions. 4 Section 1.3. Incorporation by Reference of Trust Indenture Act. 4 Section 1.4. Rules of Construction. 4 ARTICLE II. THE SECURITIES 5 Section 2.1. Issuable in Series. 5 Section 2.2. Establishment of Term

March 3, 2022 EX-21.1

List of Subsidiaries of the Registrant.

Exhibit 21.1 List of Subsidiaries of Gossamer Bio, Inc. Name Jurisdiction of Incorporation or Organization GB002, Inc. Delaware GB004, Inc. Delaware Gossamer Bio Services, Inc. Delaware

March 3, 2022 S-8

As filed with the Securities and Exchange Commission on March 3, 2022

Table of Contents As filed with the Securities and Exchange Commission on March 3, 2022 Registration No.

March 3, 2022 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) Gossamer Bio, Inc.

March 3, 2022 EX-99.1

Gossamer Bio Announces Fourth Quarter and Full-Year 2021 Financial Results and Provides Business Update - GB004 topline results for the Phase 2 SHIFT-UC study in mild-to-moderate UC expected in the second quarter of 2022 - - Seralutinib (GB002) topli

Exhibit 99.1 Gossamer Bio Announces Fourth Quarter and Full-Year 2021 Financial Results and Provides Business Update - GB004 topline results for the Phase 2 SHIFT-UC study in mild-to-moderate UC expected in the second quarter of 2022 - - Seralutinib (GB002) topline results for the Phase 2 TORREY study in PAH expected in the second half of 2022, subject to developments in the ongoing COVID-19 pande

February 10, 2022 SC 13G/A

GOSS / Gossamer Bio Inc / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 2)* Name of issuer: Gossamer Bio Inc. Title of Class of Securities: Common Stock CUSIP Number: 38341P102 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: ☒ R

November 8, 2021 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 September 30, 2021 ☐ TRANSITION REPORT PURSUANT

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, 2021 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: 001-387

November 8, 2021 EX-99.1

Gossamer Bio Announces Third Quarter 2021 Financial Results and Provides Corporate Update - Topline Results from Ongoing Phase 2 TORREY Study of Seralutinib in Patients with PAH Now Expected in Second Half of 2022, Due to COVID-19-Related Delays - -

Exhibit 99.1 Gossamer Bio Announces Third Quarter 2021 Financial Results and Provides Corporate Update - Topline Results from Ongoing Phase 2 TORREY Study of Seralutinib in Patients with PAH Now Expected in Second Half of 2022, Due to COVID-19-Related Delays - - Phase 2 SHIFT-UC Study of GB004 in Patients with UC has Completed Enrollment with 12-Week Topline Results Expected in the Second Quarter

November 8, 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 8, 2021 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

October 12, 2021 EX-99.1

Gossamer Bio Announces Addition of Two CNS-Penetrant BTK Inhibitors to its Product Candidate Pipeline: GB5121 & GB7208

Exhibit 99.1 Gossamer Bio Announces Addition of Two CNS-Penetrant BTK Inhibitors to its Product Candidate Pipeline: GB5121 & GB7208 SAN DIEGO ? (BUSINESS WIRE) ? October 11, 2021 ? Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutics in the disease areas of immunology, inflammation and oncology,

October 12, 2021 8-K

Regulation FD Disclosure, 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 11, 2021 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

September 21, 2021 EX-99.1

Gossamer Bio Announces Appointment of Bryan Giraudo as Chief Operating Officer, in addition to Chief Financial Officer Role

Exhibit 99.1 Gossamer Bio Announces Appointment of Bryan Giraudo as Chief Operating Officer, in addition to Chief Financial Officer Role SAN DIEGO ? (BUSINESS WIRE) ? September 21, 2021 ? Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutics in the disease areas of immunology, inflammation and on

September 21, 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): September 16, 2021 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission F

August 9, 2021 EX-10.2

Employment Letter, dated May 1, 2021, by and between Laura Carter and the Registrant.

EXHIBIT 10.2 Gossamer Bio Services, Inc. 3013 Science Park Road San Diego, CA 92112 May 1, 2021 Laura Carter c/o Gossamer Bio Services, Inc. 3013 Science Park Road, Suite 200 San Diego, CA 92112 Dear Laura: This amended and restated letter agreement (this ?Agreement?) confirms the terms of your continuing employment with Gossamer Bio Services, Inc. (the ?Company?), a wholly-owned subsidiary of Gos

August 9, 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 9, 2021 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

August 9, 2021 EX-10.3

Employment Letter, dated June 21, 2021, by and between Richard Aranda and the Registrant.

EXHIBIT 10.2 Gossamer Bio Services, Inc. 3013 Science Park Road San Diego, CA 92112 June 21, 2021 Richard Aranda c/o Gossamer Bio Services, Inc. 3013 Science Park Road San Diego, CA 92112 Dear Richard: This amended and restated letter agreement (this ?Agreement?) confirms the terms of your continuing employment with Gossamer Bio Services, Inc. (the ?Company?), a wholly-owned subsidiary of Gossamer

August 9, 2021 EX-99.1

Gossamer Bio Announces Second Quarter 2021 Financial Results and Provides Corporate Update - Seralutinib and GB004 continue to enroll ongoing Phase 2 TORREY and SHIFT-UC clinical trials for Pulmonary Arterial Hypertension (PAH) and Ulcerative Colitis

Exhibit 99.1 Gossamer Bio Announces Second Quarter 2021 Financial Results and Provides Corporate Update - Seralutinib and GB004 continue to enroll ongoing Phase 2 TORREY and SHIFT-UC clinical trials for Pulmonary Arterial Hypertension (PAH) and Ulcerative Colitis (UC), respectively - - Gossamer Announces Seralutinib Open Label Extension Data in PAH Patients - - Gossamer to Discontinue Clinical Dev

August 9, 2021 EX-10.1

Employment Letter, dated April 16, 2021, by and between Caryn Peterson and the Registrant.

EXHIBIT 10.1 Gossamer Bio Services, Inc. 3013 Science Park Road San Diego, CA 92112 April 16, 2021 Caryn Peterson c/o Gossamer Bio Services, Inc. 3013 Science Park Road, Suite 200 San Diego, CA 92112 Dear Caryn: This amended and restated letter agreement (this ?Agreement?) confirms the terms of your continuing employment with Gossamer Bio Services, Inc. (the ?Company?), a wholly-owned subsidiary o

August 9, 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.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, 2021 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: 001-38796 GO

June 14, 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, 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 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

June 14, 2021 EX-99.1

Gossamer Bio Announces Appointment of Sandra Milligan, M.D., J.D., to its Board of Directors

Gossamer Bio Announces Appointment of Sandra Milligan, M.D., J.D., to its Board of Directors SAN DIEGO ? (BUSINESS WIRE) ? June 14, 2021 ? Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutics in the disease areas of immunology, inflammation and oncology, today announced the appointment of Sandra

May 6, 2021 EX-10.1

Director Compensation Prog

Exhibit 10.1 GOSSAMER BIO, INC. NON-EMPLOYEE DIRECTOR COMPENSATION PROGRAM Non-employee members of the board of directors (the ?Board?) of Gossamer Bio, Inc. (the ?Company?) shall receive cash and equity compensation as set forth in this Non-Employee Director Compensation Program (this ?Program?). This Program has been adopted under the Company?s 2019 Incentive Award Plan (the ?Equity Plan?) and s

May 6, 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 6, 2021 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Num

May 6, 2021 10-Q

Quarterly Report - 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, 2021 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: 001-38796 G

May 6, 2021 EX-99.1

Gossamer Bio Announces First Quarter 2021 Financial Results and Provides Corporate Update - Seralutinib and GB004 continue to progress through ongoing Phase 2 TORREY and SHIFT-UC clinical trials for Pulmonary Arterial Hypertension (PAH) and Ulcerativ

Exhibit 99.1 Gossamer Bio Announces First Quarter 2021 Financial Results and Provides Corporate Update - Seralutinib and GB004 continue to progress through ongoing Phase 2 TORREY and SHIFT-UC clinical trials for Pulmonary Arterial Hypertension (PAH) and Ulcerative Colitis (UC), respectively - - Cash, cash equivalents and marketable securities totaled $453 million as of March 31, 2021 - SAN DIEGO?(

April 27, 2021 DEFA14A

- 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. ) Filed by the Registrant x Filed by a Party other than the 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 27, 2021 DEF 14A

- 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. ) Filed by the Registrant x Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) x Defin

April 20, 2021 EX-99.1

Gossamer Bio Announces Executive Management Transition and Promotion of Laura Carter, Ph.D., to Chief Scientific Officer

Exhibit 99.1 Gossamer Bio Announces Executive Management Transition and Promotion of Laura Carter, Ph.D., to Chief Scientific Officer SAN DIEGO ? (BUSINESS WIRE) ? April 20, 2021 ? Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutics in the disease areas of immunology, inflammation and oncology,

April 20, 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): April 17, 2021 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

February 26, 2021 EX-10.10

Transition Agreement, dated November 17, 2020, by and between Sheila Gujrathi, M.D. and the Registrant.

Exhibit 10.10 TRANSITION AGREEMENT This Transition Agreement (the ?Agreement?) is entered into by and among Sheila Gujrathi, M.D. (?Executive?), Gossamer Bio Services, Inc. (the ?Gossamer Services?), and Gossamer Bio, Inc. (?Parent,? and together with Gossamer Services, collectively the ?Company?), effective as of the Effective Date (as defined below). Recitals WHEREAS, Executive is a party to tha

February 26, 2021 10-K

Annual Report - 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ? 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 Commission file number: 001-38796 GOSSAMER BIO, INC. (Exact name of Registrant as specified i

February 26, 2021 EX-10.11

Letter Agreement, dated November 16, 2020, by and between Faheem Hasnain and the Registrant.

Exhibit 10.11 Gossamer Bio, Inc. Gossamer Bio Services, Inc. November 16, 2020 Faheem Hasnain c/o Gossamer Bio, Inc. 3013 Science Park Road San Diego, CA 92121 Dear Mr. Hasnain: The purpose of this letter agreement (this ?Agreement?) is to memorialize the terms and conditions of your employment as President and Chief Executive Officer of Gossamer Bio, Inc. (?Parent?) and continued service as Chair

February 26, 2021 EX-4.3

Description of Securities Registered under Section 12 of the Exchange Act.

Exhibit 4.3 DESCRIPTION OF GOSSAMER BIO, INC. SECURITIES REGISTERED PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934 Gossamer Bio, Inc. has one class of securities registered under Section 12 of the Securities Exchange Act of 1934, as amended (the ?Exchange Act?): our common stock, par value $0.0001 per share (the ?common stock?). DESCRIPTION OF COMMON STOCK The following description

February 25, 2021 EX-99.1

Gossamer Bio Announces Fourth Quarter and Full-Year 2020 Financial Results and Provides Business Update - Seralutinib (GB002) and GB004 continue to progress through ongoing Phase 2 TORREY and SHIFT-UC clinical trials for Pulmonary Arterial Hypertensi

Exhibit 99.1 Gossamer Bio Announces Fourth Quarter and Full-Year 2020 Financial Results and Provides Business Update - Seralutinib (GB002) and GB004 continue to progress through ongoing Phase 2 TORREY and SHIFT-UC clinical trials for Pulmonary Arterial Hypertension (PAH) and Ulcerative Colitis (UC), respectively - - Topline results for both ongoing Phase 2 trials expected in the first half of 2022

February 25, 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): February 25, 2021 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fi

February 16, 2021 SC 13G/A

Gossamer Bio, Inc.

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Gossamer Bio, Inc. (Name of Issuer) Common Stock, par value of $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) December 31, 2020 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursuan

February 12, 2021 EX-99.2

POWER OF ATTORNEY

EX-99.2 CUSIP No. 38341P102 13G Exhibit 99.2 POWER OF ATTORNEY Know all by these presents, that each of the undersigned hereby constitutes and appoints each other undersigned, such person’s true and lawful attorney-in-fact, to: (1) execute for and on behalf of each of such person Forms 3, 4, and 5 and Schedules 13D or 13G, as appropriate, and any required amendments thereto (collectively, the “Rep

February 12, 2021 SC 13G/A

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO § 240.13d-1 (b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO § 240.13d-2 (Amendment No. 1)* Goss

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO ? 240.13d-1 (b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO ? 240.13d-2 (Amendment No. 1)* Gossamer Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 38341P102 (CUSIP Number) December 31, 2020 (Date of Event Which Requires F

February 12, 2021 EX-99.1

AGREEMENT

EX-99.1 CUSIP No. 38341P102 13G Exhibit 99.1 AGREEMENT Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of Common Stock of Gossamer Bio, Inc. Dated: February 12, 2021 OMEGA FUND V, L.P. BY:

February 12, 2021 SC 13G

United States Securities and Exchange Commission Washington, D.C. 20549 Schedule 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to § 240.13d-1(b), (c) and (d) and Amendments Thereto Filed Pursuant to § 240.13d-2 UNDER THE

United States Securities and Exchange Commission Washington, D.C. 20549 Schedule 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to ? 240.13d-1(b), (c) and (d) and Amendments Thereto Filed Pursuant to ? 240.13d-2 UNDER THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 1)* GOSSAMER BIO, INC. (Name of Issuer) Common Stock (Title of Class of Securities) 38341P102 (CUSIP Nu

February 12, 2021 SC 13G

United States Securities and Exchange Commission Washington, D.C. 20549 Schedule 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to § 240.13d-1(b), (c) and (d) and Amendments Thereto Filed Pursuant to § 240.13d-2 UNDER THE

United States Securities and Exchange Commission Washington, D.C. 20549 Schedule 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to ? 240.13d-1(b), (c) and (d) and Amendments Thereto Filed Pursuant to ? 240.13d-2 UNDER THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 1)* GOSSAMER BIO, INC. (Name of Issuer) Common Stock (Title of Class of Securities) 38341P102 (CUSIP Nu

February 10, 2021 SC 13G/A

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 1)*

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 1)* Name of issuer: Gossamer Bio Inc. Title of Class of Securities: Common Stock CUSIP Number: 38341P102 Date of Event Which Requires Filing of this Statement: December 31, 2020 Check the appropriate box to designate the rule pursuant to which this Schedule is filed: ☒ R

November 17, 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): November 16, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fi

November 10, 2020 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition - 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 10, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fi

November 10, 2020 EX-99.1

Gossamer Bio Announces Third Quarter 2020 Financial Results and Provides Corporate Update - GB004: SHIFT-UC Phase 2 trial enrolling patients with active ulcerative colitis (UC) - - GB002: TORREY Phase 2 trial activated in patients with pulmonary arte

Exhibit 99.1 Gossamer Bio Announces Third Quarter 2020 Financial Results and Provides Corporate Update - GB004: SHIFT-UC Phase 2 trial enrolling patients with active ulcerative colitis (UC) - - GB002: TORREY Phase 2 trial activated in patients with pulmonary arterial hypertension (PAH) - - GB1275: Two posters with data from ongoing Phase 1/2 KEYNOTE-A36 clinical trial in advanced solid tumors pres

November 10, 2020 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, 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: 001-387

October 13, 2020 EX-99.2

Datamonitor, open source medical claims, internal analysis. A High Unmet Need Remains for Patients with Uncontrolled Severe Asthma 1.2-1.5 mm Total Patients (US) ~85-90% ~10-15% Uncontrolled GINA 4/5 Patients With High Eos. Injectable biologics (Inc.

GB001 Phase 2 Clinical Trial Topline Results October 13, 2020 Exhibit 99.2 This presentation contains forward-looking statements. All statements other than statements of historical facts contained in this presentation, including statements regarding the potential for the LEDA Study results to allow for the design of a well-powered Phase 3 program for GB001 and our plans to discuss such results wit

October 13, 2020 EX-99.1

Gossamer Bio Announces Topline Results for Phase 2 Trials of Oral GB001 in Asthma and Chronic Rhinosinusitis - Primary endpoint of asthma worsening not met in LEDA Study, however consistent numeric reductions ranging from 32-35% observed across all t

Exhibit 99.1 Gossamer Bio Announces Topline Results for Phase 2 Trials of Oral GB001 in Asthma and Chronic Rhinosinusitis - Primary endpoint of asthma worsening not met in LEDA Study, however consistent numeric reductions ranging from 32-35% observed across all three GB001 groups - - Statistically significant improvements in key secondary endpoint of time to first asthma worsening of 28% and 30% o

October 13, 2020 8-K

Regulation FD Disclosure, 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 13, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

August 11, 2020 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, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

August 11, 2020 EX-10.2

Amendment No. 1 to License Agreement, dated May 11, 2020, by and between GB004, Inc. and Aerpio Pharmaceuticals, Inc.

Exhibit 10.2 CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THE EXHIBIT BECAUSE IT BOTH (I) IS NOT MATERIAL AND (II) WOULD LIKELY BE COMPETITIVELY HARMFUL IF PUBLICLY DISCLOSED. SUCH EXCLUDED INFORMATION HAS BEEN MARKED WITH “[***]”. AMENDMENT NO. 1 TO LICENSE AGREEMENT This Amendment No. 1 to License Agreement (this “Amendment”), dated as of May 11, 2020 (but only effective as of the Amend

August 11, 2020 EX-99.1

Gossamer Bio Announces Second Quarter 2020 Financial Results and Provides Corporate Update - GB001: Phase 2 studies, LEDA in eosinophilic asthma and TITAN in chronic rhinosinusitis, on track for topline data readout in the second half of 2020 - - GB0

Exhibit 99.1 Gossamer Bio Announces Second Quarter 2020 Financial Results and Provides Corporate Update - GB001: Phase 2 studies, LEDA in eosinophilic asthma and TITAN in chronic rhinosinusitis, on track for topline data readout in the second half of 2020 - - GB002: Expected to commence Phase 2 TORREY study in pulmonary arterial hypertension in the second half of 2020 - - GB004: Expected to commen

August 11, 2020 10-Q

Quarterly Report - 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: 001-38796 GOSSAMER BIO, INC. (

July 2, 2020 8-K

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant

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 2, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

July 2, 2020 EX-10.1

Second Amendment to Credit, Guaranty and Security Agreement, dated July 2, 2020, by and among the Registrant, GB001, Inc., GB002, Inc. and GB004, Inc., as co-borrowers, the other guarantors from time to time party thereto and MidCap Financial Trust, as Agent and as a Lender and the additional lenders from time to time party thereto.

Exhibit 10.1 SECOND aMENDMENT TO CREDIT, GUARANTY AND SECURITY AGREEMENT This SECOND AMENDMENT TO CREDIT, GUARANTY AND SECURITY AGREEMENT (this “Agreement”) is made as of this 2nd day of July, 2020 (“Effective Date”), by and among GB001, INC., a Delaware corporation (“GB001”), GOSSAMER BIO, INC., Delaware corporation (“Parent”), GB002, INC., a Delaware corporation (“GB002”), GB004, INC., a Delawar

June 18, 2020 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 17, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

May 21, 2020 EX-4.2

First Supplemental Indenture, dated May 21, 2020, by and between the Company and Wilmington Trust, National Association.

Exhibit 4.2 GOSSAMER BIO, INC. and WILMINGTON TRUST, NATIONAL ASSOCIATION as Trustee FIRST SUPPLEMENTAL INDENTURE Dated as of May 21, 2020 5.00% Convertible Senior Notes due 2027 CROSS REFERENCE TABLE* Trust Indenture Act Indenture Section Section 310 (a)(1) N/A (a)(2) N/A (a)(3) N/A (a)(4) N/A (a)(5) N/A (b) N/A (c) N/A 311 (a) N/A (b) N/A (c) N/A 312 (a) 2.08 (b) N/A (c) N/A 313 (a) N/A (b)(1) N

May 21, 2020 EX-99.2

Gossamer Bio Announces Pricing of Concurrent Public Offerings of Common Stock and Convertible Senior Notes due 2027

Exhibit 99.2 Gossamer Bio Announces Pricing of Concurrent Public Offerings of Common Stock and Convertible Senior Notes due 2027 SAN DIEGO—(BUSINESS WIRE)— May 19, 2020 – Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutics in the disease areas of immunology, inflammation and oncology, today ann

May 21, 2020 EX-99.1

Gossamer Bio Announces Proposed Concurrent Public Offerings of Common Stock and Convertible Senior Notes due 2027

Exhibit 99.1 Gossamer Bio Announces Proposed Concurrent Public Offerings of Common Stock and Convertible Senior Notes due 2027 SAN DIEGO—(BUSINESS WIRE)— May 18, 2020 – Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutics in the disease areas of immunology, inflammation and oncology, today annou

May 21, 2020 8-K

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant, 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): May 18, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 21, 2020 EX-4.1

Indenture, dated as of May 21, 2020, by and between the Company and Wilmington Trust, National Association.

Exhibit 4.1 GOSSAMER BIO, INC. INDENTURE Dated as of May 21, 2020 WILMINGTON TRUST, NATIONAL ASSOCIATION, as Trustee TABLE OF CONTENTS Page ARTICLE I. DEFINITIONS AND INCORPORATION BY REFERENCE 1 Section 1.1. Definitions. 1 Section 1.2. Other Definitions. 4 Section 1.3. Incorporation by Reference of Trust Indenture Act. 5 Section 1.4. Rules of Construction. 5 ARTICLE II. THE SECURITIES 5 Section 2

May 21, 2020 EX-1.2

Underwriting Agreement, dated May 18, 2020, related to the Notes

Exhibit 1.2 GOSSAMER BIO, INC. (a Delaware corporation) 5.00% Convertible Senior Unsecured Notes Due 2027 UNDERWRITING AGREEMENT Dated: May 18, 2020 GOSSAMER BIO, INC. (a Delaware corporation) 5.00% Convertible Senior Unsecured Notes Due 2027 UNDERWRITING AGREEMENT May 18, 2020 BofA Securities, Inc. SVB Leerink LLC Piper Sandler & Co. as Representatives of the several Underwriters named in Schedul

May 21, 2020 EX-1.1

Underwriting Agreement, dated May 18, 2020, related to the Common Stock

Exhibit 1.1 GOSSAMER BIO, INC. (a Delaware corporation) 9,433,963 Shares of Common Stock UNDERWRITING AGREEMENT Dated: May 18, 2020 GOSSAMER BIO, INC. (a Delaware corporation) 9,433,963 Shares of Common Stock UNDERWRITING AGREEMENT May 18, 2020 BofA Securities, Inc. SVB Leerink LLC as Representatives of the several Underwriters named in Schedule A hereto c/o BofA Securities, Inc. One Bryant Park N

May 19, 2020 FWP

Gossamer Bio, Inc. Concurrent Offerings of 9,433,963 Shares of Common Stock, par value $0.0001 per Share (the “Common Stock Offering”) $200,000,000 Aggregate Principal Amount of 5.00% Convertible Senior Notes due 2027 (the “Convertible Notes Offering

FWP Issuer Free Writing Prospectus Filed pursuant to Rule 433 Registration File No.

May 19, 2020 424B5

CALCULATION OF REGISTRATION FEE

Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-237639 CALCULATION OF REGISTRATION FEE Title of each Class of Securities to be Registered Amount to Be Registered Proposed Maximum Offering Price Per Unit Proposed Maximum Aggregate Offering Price Amount of Registration Fee 5.00% Convertible Senior Notes due 2027 $230,000,000.00(1)(2) 100% $230,000,000.00(2) $29,854.00(3) Comm

May 19, 2020 424B5

CALCULATION OF REGISTRATION FEE

Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-237639 CALCULATION OF REGISTRATION FEE Title of Each Class of Securities to be Registered Amount to be Registered(1) Proposed Maximum Offering Price Per Unit Proposed Maximum Aggregate Offering Price Amount of Registration Fee(2) Common Stock, $0.0001 par value 10,849,057 $ 13.25 $ 143,750,006 $ 18,658.76 (1) Includes 1,415,09

May 18, 2020 FWP

Gossamer Bio Announces Proposed Concurrent Public Offerings of Common Stock and Convertible Senior Notes due 2027

FWP Filed Pursuant to Rule 433 Registration No. 333-237639 Issuer Free Writing Prospectus, dated May 18, 2020 Gossamer Bio Announces Proposed Concurrent Public Offerings of Common Stock and Convertible Senior Notes due 2027 SAN DIEGO—(BUSINESS WIRE)—May 18, 2020—Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercia

May 18, 2020 424B5

Subject to Completion Preliminary Prospectus Supplement dated May 18, 2020

Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-237639 The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell, nor a solicitation of an offer to buy, these securities in any jurisdiction where the offer or sale is not permitted. Subject to C

May 18, 2020 424B5

Subject to Completion Preliminary Prospectus Supplement dated May 18, 2020

Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-237639 Subject to Completion Preliminary Prospectus Supplement dated May 18, 2020 PROSPECTUS SUPPLEMENT (To prospectus dated April 10, 2020) The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to se

May 12, 2020 10-Q

Form 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 March 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: 001-38796 GOSSAMER BIO, INC.

May 12, 2020 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, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 12, 2020 EX-99.1

Gossamer Bio Announces First Quarter 2020 Financial Results and Provides Corporate Update - GB001 interim analysis of LEDA trial in moderate-to-severe eosinophilic asthma completed - - GB001 intellectual property estate strengthened with issuance of

Exhibit 99.1 Gossamer Bio Announces First Quarter 2020 Financial Results and Provides Corporate Update - GB001 interim analysis of LEDA trial in moderate-to-severe eosinophilic asthma completed - - GB001 intellectual property estate strengthened with issuance of new patent by USPTO covering lysine salt drug substance forms - - GB004 completed successful Phase 1b in ulcerative colitis; Phase 2 tria

May 12, 2020 EX-3.2

Amended and Restated Bylaws.

Exhibit 3.2 AMENDED AND RESTATED BYLAWS OF GOSSAMER BIO, INC. (a Delaware corporation) TABLE OF CONTENTS Page ARTICLE I - CORPORATE OFFICES 1 1.1 REGISTERED OFFICE 1 1.2 OTHER OFFICES 1 ARTICLE II - MEETINGS OF STOCKHOLDERS 1 2.1 PLACE OF MEETINGS 1 2.2 ANNUAL MEETING 1 2.3 SPECIAL MEETING 2 2.4 ADVANCE NOTICE PROCEDURES FOR BUSINESS BROUGHT BEFORE A MEETING 2 2.5 ADVANCE NOTICE PROCEDURES FOR NOM

May 12, 2020 EX-10.1

Gossamer Bio, Inc. Restricted Stock Unit Agreement under the 2019 Equity Incentive Plan.

Exhibit 10.1 GOSSAMER BIO, INC. 2019 INCENTIVE AWARD PLAN RESTRICTED STOCK Unit Grant Notice Capitalized terms not specifically defined in this Restricted Stock Unit Grant Notice (the “Grant Notice”) have the meanings given to them in the 2019 Incentive Award Plan (as amended from time to time, the “Plan”) of Gossamer Bio, Inc. (the “Company”). The Company hereby grants to the participant listed b

April 27, 2020 DEFA14A

- 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. ) Filed by the Registrant ☒ Filed by a Party other than the 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 27, 2020 DEF 14A

Schedule 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. ) Filed by the Registrant ☒ Filed by a Party other than the 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, 2020 S-3ASR

GOSS / Gossamer Bio, Inc. S-3ASR - - S-3ASR

As filed with the Securities and Exchange Commission on April 10, 2020 Registration No.

April 10, 2020 EX-4.4

Form of Indenture

Exhibit 4.4 GOSSAMER BIO, INC. INDENTURE Dated as of , 20 [] Trustee TABLE OF CONTENTS Page ARTICLE I. DEFINITIONS AND INCORPORATION BY REFERENCE 1 Section 1.1. Definitions 1 Section 1.2. Other Definitions 4 Section 1.3. Incorporation by Reference of Trust Indenture Act 5 Section 1.4. Rules of Construction 5 ARTICLE II. THE SECURITIES 5 Section 2.1. Issuable in Series 5 Section 2.2. Establishment

March 24, 2020 EX-21.1

List of Subsidiaries of the Registrant.

Exhibit 21.1 List of Subsidiaries of Gossamer Bio, Inc. Name Jurisdiction of Incorporation or Organization GB001, Inc. Delaware GB002, Inc. Delaware GB004, Inc. Delaware GB006, Inc. Delaware Gossamer Bio Services, Inc. Delaware

March 24, 2020 EX-99.1

Gossamer Bio Announces Fourth Quarter and Full-Year 2019 Financial Results and Provides Business Update - Clinical trial results for all four clinical-stage product candidates in target areas of immunology, inflammation and oncology expected in 2020

Exhibit 99.1 Gossamer Bio Announces Fourth Quarter and Full-Year 2019 Financial Results and Provides Business Update - Clinical trial results for all four clinical-stage product candidates in target areas of immunology, inflammation and oncology expected in 2020 – - Cash, cash equivalents and marketable securities totaled $401.8 million at year-end 2019 - SAN DIEGO—(BUSINESS WIRE)—March 24, 2020—G

March 24, 2020 10-K

Form 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2019 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission file number: 001-38796 GOSSAMER BIO, INC. (Exact name of Registrant as specified in

March 24, 2020 EX-4.3

Exhibit 4.3

Exhibit 4.3 DESCRIPTION OF GOSSAMER BIO, INC. SECURITIES REGISTERED PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934 Gossamer Bio, Inc. has one class of securities registered under Section 12 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”): our common stock, par value $0.0001 per share (the “common stock”). DESCRIPTION OF COMMON STOCK The following description

March 24, 2020 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 24, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

February 14, 2020 SC 13G

GOSS / Gossamer Bio, Inc. / Omega Fund V, L.p. - SC 13G Passive Investment

SC 13G SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO § 240.13d-1 (b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO § 240.13d-2 Gossamer Bio, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 38341P102 (CUSIP Number) December 31, 2019 (Date of Event Which Requires Filing of thi

February 14, 2020 EX-99.2

POWER OF ATTORNEY

EX-99.2 Exhibit 99.2 CUSIP NO. 38341P102 13G POWER OF ATTORNEY Know all by these presents, that each of the undersigned hereby constitutes and appoints each other undersigned, such person’s true and lawful attorney-in-fact, to: (1) execute for and on behalf of each of such person Forms 3, 4, and 5 and Schedules 13D or 13G, as appropriate, and any required amendments thereto (collectively, the “Rep

February 14, 2020 EX-99.1

AGREEMENT

EX-99.1 Exhibit 99.1 CUSIP NO. 38341P102 13G AGREEMENT Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of Common Stock of Cidara Therapeutics, Inc. Dated: February 13, 2020 OMEGA FUND V, L

February 14, 2020 SC 13G

GOSS / Gossamer Bio, Inc. / Hillhouse Capital Advisors, Ltd. - GOSSAMER BIO, INC. Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Gossamer Bio, Inc. (Name of Issuer) Common Stock, par value of $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) December 31, 2019 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursuant t

February 13, 2020 SC 13G

GOSS / Gossamer Bio, Inc. / Arch Venture Fund Ix, L.p. - ARCH VENTURE FUND IX, L.P. - GOSSAMER BIO, INC. -- SCHEDULE 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Gossamer Bio, Inc. (Name of Issuer) Common Stock par value $0.0001 per share (Title of Class of Securities) 38341P102 (CUSIP Number) December 31, 2019 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule

February 11, 2020 SC 13G

GOSS / Gossamer Bio, Inc. / 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: Gossamer Bio Inc Title of Class of Securities: Common Stock CUSIP Number: 38341P102 Date of Event Which Requires Filing of this Statement: December 31, 2019 Check the appropriate box to designate the rule pursuant to which this Schedule is filed: ☒ Rule 13d-1(b) ☐ Rule 1

February 10, 2020 SC 13G

GOSS / Gossamer Bio, Inc. / Hasnain Faheem - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to § 240.13d-1(b), (c) and (d) and Amendments Thereto Filed Pursuant to § 240.13d-2 Under the Securities Exchange Act of 1934 (Amendment No. )* GOSSAMER BIO, INC. (Name of Issuer) Common Stock (Title of Class of Securities) 38341P102 (CUSIP Num

February 10, 2020 SC 13G

GOSS / Gossamer Bio, Inc. / Gujrathi Sheila - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G (Rule 13d-102) Information to be Included in Statements Filed Pursuant to § 240.13d-1(b), (c) and (d) and Amendments Thereto Filed Pursuant to § 240.13d-2 Under the Securities Exchange Act of 1934 (Amendment No. )* GOSSAMER BIO, INC. (Name of Issuer) Common Stock (Title of Class of Securities) 38341P102 (CUSIP Num

January 13, 2020 8-K

Regulation FD Disclosure

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 13, 2020 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fil

November 12, 2019 EX-10.1

First Amendment to Credit, Guaranty and Security Agreement, dated September 18, 2019, by and among GB001, Inc., as borrower, the Registrant, as guarantor, the other guarantors from time to time party thereto and MidCap Financial Trust, as Agent and as Lender, and the additional lenders from time to time party thereto.

Exhibit 10.1 OMNIBUS FIRST aMENDMENT TO CREDIT, GUARANTY AND SECURITY AGREEMENT and FIRST AMENDMENT TO PLEDGE AGREEMENT This OMNIBUS FIRST AMENDMENT TO CREDIT, GUARANTY AND SECURITY AGREEMENT AND FIRST AMENDMENT TO PLEDGE AGREEMENT (this “Agreement”) is made as of this 18th day of September, 2019 (“Effective Date”), by and among GB001, INC., a Delaware corporation (“Borrower”), GOSSAMER BIO, INC.,

November 12, 2019 10-Q

GOSS / Gossamer Bio, Inc. 10-Q - Quarterly Report - 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 September 30, 2019 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: 001-38796 GOSSAMER BIO, I

November 12, 2019 EX-99.1

Gossamer Bio Announces Third Quarter 2019 Financial Results – Clinical programs on track for multiple topline data releases in 2020 – – Entered clinical trial collaboration with Merck to evaluate KEYTRUDA® (pembrolizumab) in combination with GB1275 i

Exhibit 99.1 Gossamer Bio Announces Third Quarter 2019 Financial Results – Clinical programs on track for multiple topline data releases in 2020 – – Entered clinical trial collaboration with Merck to evaluate KEYTRUDA® (pembrolizumab) in combination with GB1275 in advanced solid tumors – – Company to host conference call today at 4:30 p.m. ET – SAN DIEGO, Calif., Nov. 12, 2019 – Gossamer Bio, Inc.

November 12, 2019 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 12, 2019 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission Fi

September 13, 2019 8-K

Current Report

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 12, 2019 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission F

August 8, 2019 EX-99.1

Gossamer Bio Announces Second Quarter 2019 Financial Results – Immuno-oncology candidate, GB1275, advances to clinic for selected solid tumor types – – Five active clinical trials across four clinical programs, with data readouts for all four program

Exhibit 99.1 Gossamer Bio Announces Second Quarter 2019 Financial Results – Immuno-oncology candidate, GB1275, advances to clinic for selected solid tumor types – – Five active clinical trials across four clinical programs, with data readouts for all four programs expected in 2020 – – Company to host conference call today at 4:30 p.m. ET – SAN DIEGO, Calif., Aug. 8, 2019 – Gossamer Bio, Inc. (Nasd

August 8, 2019 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 8, 2019 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File

August 8, 2019 10-Q

GOSS / Gossamer Bio, Inc. 10-Q - Quarterly Report - 10-Q - Q2 FY2019

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, 2019 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: 001-38796 GOSSAMER BIO, INC. (

August 8, 2019 EX-10.2

Letter Agreement, dated June 3, 2019, by and between Faheem Hasnain and the Registrant

EXHIBIT 10.2 Gossamer Bio, Inc. Gossamer Bio Services, Inc. June 3, 2019 Faheem Hasnain c/o Gossamer Bio, Inc. 3013 Science Park Road San Diego, CA 92121 Dear Mr. Hasnain: The purpose of this letter agreement (this “Agreement”) is to memorialize the terms and conditions of your continued service as Chairman of the Board of Directors (the “Board”) of Gossamer Bio, Inc. (“Parent”). Effective as of J

June 11, 2019 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 10, 2019 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File N

May 30, 2019 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): May 30, 2019 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 14, 2019 EX-99.1

Gossamer Bio Announces First Quarter 2019 Financial Results – Multiple trial initiations and data readouts expected in the next 12 months – – Company to host conference call today at 8:30 a.m. ET –

Exhibit 99.1 Gossamer Bio Announces First Quarter 2019 Financial Results – Multiple trial initiations and data readouts expected in the next 12 months – – Company to host conference call today at 8:30 a.m. ET – SAN DIEGO, Calif., May 14, 2019 – Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutic

May 14, 2019 EX-99.2

Forward Looking Statement This presentation contains forward-looking statements. All statements other than statements of historical facts contained in this presentation, including statements regarding our future results of operations and financial po

Confidential Corporate Presentation Exhibit 99.2 Forward Looking Statement This presentation contains forward-looking statements. All statements other than statements of historical facts contained in this presentation, including statements regarding our future results of operations and financial position, business strategy, prospective products, product approvals, research and development costs, t

May 14, 2019 8-K

Regulation FD Disclosure, 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 14, 2019 GOSSAMER BIO, INC. (Exact name of Registrant as Specified in Its Charter) Delaware 001-38796 47-5461709 (State or Other Jurisdiction of Incorporation) (Commission File Nu

May 14, 2019 10-Q

GOSS / Gossamer Bio, Inc. 10-Q Quarterly Report 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 March 31, 2019 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: 001-38796 GOSSAMER BIO, INC.

May 3, 2019 EX-99.1

Gossamer Bio Secures Debt Facility for Up to $150 Million

Exhibit 99.1 Gossamer Bio Secures Debt Facility for Up to $150 Million SAN DIEGO, Calif., May 2, 2019 – Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutics in the disease areas of immunology, inflammation and oncology, today announced it entered into a five-year senior debt facility led by MidC

May 3, 2019 8-K

Entry into a Material Definitive Agreement, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant

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 2, 2019 GOSSAMER BIO, INC. (Exact name of registrant as specified in its charter) Delaware 001-38796 47-5461709 (State or other jurisdiction of incorporation or organization) (Com

May 3, 2019 EX-10.1

Credit, Guaranty and Security Agreement, dated May 2, 2019, by and among GB001, Inc., as Borrower, Gossamer Bio, Inc., as Guarantor, MidCap Financial Trust, as Agent and Lender, and the additional lenders from time to time party thereto.

Exhibit 10.1 CREDIT, GUARANTY AND SECURITY AGREEMENT dated as of May 2, 2019 by and among GB001, Inc., as Borrower and any additional borrower that hereafter becomes party hereto, GOSSAMER BIO, INC., as Guarantor and the Guarantors from time to time party hereto, and MIDCAP FINANCIAL TRUST, as Agent and as a Lender, and THE ADDITIONAL LENDERS FROM TIME TO TIME PARTY HERETO CREDIT, GUARANTY AND SEC

April 30, 2019 DEF 14A

Schedule 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. ) Filed by the Registrant ☒ Filed by a Party other than the 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 30, 2019 DEFA14A

GOSS / Gossamer Bio, Inc. DEFA14A 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. ) Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ Defin

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