SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549

SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 5)*

Gossamer Bio, Inc. (Name of Issuer)

Common Stock, $0.0001 par value per share (Title of Class of Securities)

(CUSIP Number)

D. E. Shaw & Co., L.P. Legal & Compliance, Two Manhattan West, 375 Ninth Ave., 52nd Floor New York, NY, 10001 212-478-0000 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

10/06/2026 (Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No.

1	Name of reporting person D. E. Shaw Valence Portfolios, L.L.C.
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 358,693.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 275,361.00
11	Aggregate amount beneficially owned by each reporting person 358,693.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 5.9 %
14	Type of Reporting Person (See Instructions) OO

SCHEDULE 13D

CUSIP No.

1	Name of reporting person D. E. Shaw & Co., L.L.C.
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) AF
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 369,459.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 289,551.00
11	Aggregate amount beneficially owned by each reporting person 369,459.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 6.0 %
14	Type of Reporting Person (See Instructions) OO

SCHEDULE 13D

CUSIP No.

1	Name of reporting person D. E. Shaw & Co., L.P.
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) AF
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 369,459.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 289,551.00
11	Aggregate amount beneficially owned by each reporting person 369,459.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 6.0 %
14	Type of Reporting Person (See Instructions) IA, PN

SCHEDULE 13D

CUSIP No.

1	Name of reporting person David E. Shaw
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) AF
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 369,459.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 289,551.00
11	Aggregate amount beneficially owned by each reporting person 369,459.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 6.0 %
14	Type of Reporting Person (See Instructions) IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, $0.0001 par value per share
(b)	Name of Issuer: Gossamer Bio, Inc.
(c)	Address of Issuer's Principal Executive Offices: 3115 Merryfield Row, Suite 120, San Diego, CALIFORNIA , 92121.
Item 1 Comment: Introductory Note: This Amendment No. 5 ("Amendment No. 5") to the Schedule 13D (the "Initial 13D"), related to the Common Shares of the Issuer previously filed by the Reporting Persons with the SEC on June 11, 2026, as amended and supplemented by Amendment No. 1 filed on July 1, 2026, Amendment No. 2 filed on July 24, 2026, Amendment No. 3 filed on August 24, 2026, and Amendment No. 4 filed on September 28, 2026 (as amended, the "Schedule 13D"), is filed by and on behalf of each of the Reporting Persons to correct Amendment No. 4, which inadvertently understated (i) the number of Common Shares with respect to which the Reporting Persons had the power to vote or direct the vote, (ii) the aggregate amount beneficially owned by each Reporting Person, and (iii) the percent of class represented by the aggregate amount beneficially owned by each Reporting Person. Such figures are corrected in Rows (8), (11), and (13) of the cover pages and in Item 5 hereof and apply as of both the date hereof and the date of Amendment No. 4. Such corrections resulted from a review following the receipt of ballots in connection with the Issuer's Special Meeting of Stockholders to be held on October 27, 2026 (the "October Meeting"). Each capitalized term used and not defined herein shall have the meaning assigned to such term in the Schedule 13D. Except as provided herein, each Item of the Schedule 13D remains unchanged. The Initial 13D and Amendments No. 1, 2, and 3 accurately reported the Common Shares as to which the Reporting Persons had the power to dispose or direct the disposition. However, following the review referenced above, it was determined that the Reporting Persons retained the power to vote or direct the vote over Common Shares (in addition to those reported in the Initial 13D and Amendments No. 1, 2, and 3, as of the respective dates thereof) in the following amounts: DESCO LP and Dr. Shaw, 1,764,478, 7,619,047, 7,239,485, and 8,661,085 Common Shares; DESCO LLC, 1,886,593, 7,741,162, 7,239,485, and 8,661,085 Common Shares; and Valence, 1,706,001, 7,258,782, 7,239,485, and 8,661,085 Common Shares, respectively. This difference resulted from account segregation measures implemented by custodians in connection with the Voting Agreements (the form of which is attached as Exhibit 99.6 hereto) that preserved voting power over Common Shares.
Item 5.	Interest in Securities of the Issuer
(a)	Item 5(a) of the Schedule 13D is hereby amended and restated as follows: (a) - (b) The responses of the Reporting Persons to Rows (8), (11), and (13) of the cover pages of this Amendment No. 5 include Common Shares sold by certain of the Reporting Persons or their affiliates prior to the date hereof because, notwithstanding such sales, the Reporting Persons retain the power to vote such sold shares at the October Meeting, as a result of certain custodial account measures noted above that were in place as of September 14, 2026, the record date for such special meeting. Based upon the Issuer's definitive proxy statement, filed with the SEC on September 16, 2026, there were 6,116,391 Common Shares issued and outstanding as of September 14, 2026, which amount reflects the impact of the Reverse Stock Split. Common Shares are beneficially owned by Valence and Cogence. Each of Valence and Cogence is a Delaware limited liability company and has its business address and principal office at Two Manhattan West, 375 Ninth Avenue, 52nd Floor, New York, NY 10001. The 358,693 Common Shares beneficially owned by Valence (the "Valence Shares") represent approximately 5.9% of the outstanding Common Shares. The 14,190 Common Shares beneficially owned by Cogence (the "Cogence Shares") represent approximately 0.2% of the outstanding Common Shares. Valence has the power to vote or direct the vote of 358,693 of the Valence Shares and the power to dispose or direct the disposition of 275,361 of the Valence Shares. Cogence has the power to vote or direct the vote of 10,766 of the Cogence Shares and the power to dispose or direct the disposition of 14,190 of the Cogence Shares. DESCO LP, as the investment adviser of Valence and Cogence, may be deemed to have the shared power to vote or direct the vote of 369,459 Common Shares and the shared power to dispose or direct the disposition of 289,551 Common Shares. DESCO LLC, as the manager of Valence and Cogence, may be deemed to have the shared power to vote or direct the vote of 369,459 Common Shares and the shared power to dispose or direct the disposition of 289,551 Common Shares. As general partner of DESCO LP, DESCO Inc. may be deemed to have the shared power to vote or direct the vote of 369,459 Common Shares and the shared power to dispose or direct the disposition of 289,551 Common Shares. As managing member of DESCO LLC, DESCO II, Inc. may be deemed to have the shared power to vote or direct the vote of 369,459 Common Shares and the shared power to dispose or direct the disposition of 289,551 Common Shares. None of DESCO LP, DESCO LLC, DESCO Inc., or DESCO II, Inc. owns any Common Shares directly, and each such entity disclaims beneficial ownership of any Common Shares. Dr. Shaw does not own any Common Shares directly. By virtue of Dr. Shaw's position as President and sole shareholder of DESCO Inc., which is the general partner of DESCO LP, which in turn is the investment adviser of Valence and Cogence, and by virtue of Dr. Shaw's position as President and sole shareholder of DESCO II, Inc., which is the managing member of DESCO LLC, which in turn is the manager of Valence and Cogence, Dr. Shaw may be deemed to have the shared power to vote or direct the vote of 369,459 Common Shares and the shared power to dispose or direct the disposition of 289,551 Common Shares, the 369,459 Common Shares as described above constituting 6.0% of the outstanding Common Shares, and, therefore, Dr. Shaw may be deemed to be the beneficial owner of such Common Shares. Dr. Shaw disclaims beneficial ownership of any Common Shares.
(b)	Item 5(b) of the Schedule 13D is hereby amended and supplemented as follows: See Item 5(a) of Amendment No. 5 to the Schedule 13D.
(c)	Item 5(c) of the Schedule 13D is hereby amended and supplemented as follows: Schedule I to Amendment No. 5, which is incorporated by reference into this Item 5(c) as if restated in full herein, describes all of the transactions in Common Shares by the Reporting Persons and/or any affiliates of the Reporting Persons since Amendment No. 4.
(d)	Item 5(d) of the Schedule 13D is hereby amended and restated as follows: To the best of the Reporting Persons' knowledge, no person other than the Reporting Persons or their affiliates has the right to receive or power to direct the receipt of dividends from, or proceeds from the sale, of the Common Shares reported herein, except for such rights and powers as the corresponding investors in Valence and Cogence shall possess.
(e)	Item 5(e) of the Schedule 13D is hereby amended and restated as follows: Not applicable. See Item 5(a) of Amendment No. 5 to the Schedule 13D.
Item 7.	Material to be Filed as Exhibits.
	Item 7 of the Schedule 13D is hereby amended and supplemented as follows: Exhibit 99.1 - Schedule I (Transactions in the Securities of the Issuer Since Amendment No. 4) Exhibit 99.2 - Power of Attorney, granted by David E. Shaw relating to D. E. Shaw & Co., Inc., in favor of the signatories hereto, among others, dated August 1, 2024. Exhibit 99.3 - Power of Attorney, granted by David E. Shaw relating to D. E. Shaw & Co. II, Inc., in favor of the signatories hereto, among others, dated August 1, 2024. Exhibit 99.4 - Joint Filing Agreement, by and among the Reporting Persons, dated October 8, 2026. Exhibit 99.5 - Transaction Support Agreement with the Issuer, dated May 18, 2026, incorporated by reference to Exhibit 10.1 to the Form 8-K filed by the Issuer on May 18, 2026. (https://www.sec.gov/Archives/edgar/data/1728117/000172811726000036/goss-20260518xexx101xtsa.htm) Exhibit 99.6 - Form of Voting Agreement, dated May 18, 2026, incorporated by reference herein to Exhibit 10.2 to the Form 8-K filed by the Issuer on May 18, 2026. (https://www.sec.gov/Archives/edgar/data/1728117/000172811726000036/goss-20260518xexx102xformo.htm) Exhibit 99.7 - Indenture governing Senior Secured First Lien Convertible Notes due 2030, incorporated by reference to Exhibit 10.1 to the Form 8-K filed by the Issuer on June 5, 2026. (https://www.sec.gov/Archives/edgar/data/1728117/000172811726000045/goss-20260604xexx101inde.htm) Exhibit 99.8 - Purchase Warrant Agreement, dated June 4, 2026, incorporated by reference herein to Exhibit 10.3 to the Form 8-K filed by the Issuer on June 5, 2026. (https://www.sec.gov/Archives/edgar/data/1728117/000172811726000045/goss-20260604xexx103warr.htm)

SIGNATURE
	After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

D. E. Shaw Valence Portfolios, L.L.C.

Signature: /s/ Daniel R. Marcus Name/Title: Daniel R. Marcus / Authorized Signatory Date: 10/08/2026

D. E. Shaw & Co., L.L.C.

Signature: /s/ Daniel R. Marcus Name/Title: Daniel R. Marcus / Authorized Signatory Date: 10/08/2026

D. E. Shaw & Co., L.P.

Signature: /s/ Daniel R. Marcus Name/Title: Daniel R. Marcus / Chief Compliance Officer Date: 10/08/2026

David E. Shaw

Signature: /s/ Daniel R. Marcus Name/Title: Daniel R. Marcus / Attorney-in-Fact for David E. Shaw Date: 10/08/2026

SCHEDULE I

Transactions in the Securities of the Issuer Since Amendment No. 4

¹Price per Common Share does not include any brokerage commissions or service charges. Where weighted average price is used for the reported transactions, the Reporting Persons undertake to provide upon request by the SEC, full information regarding the number of Common Shares purchased or sold at each separate price.

²A weighted average price based on prices ranging from $11.36 to $11.79.

³A weighted average price based on prices ranging from $11.21 to $11.79.

⁴A weighted average price based on prices ranging from $11.49 to $12.02.

⁵A weighted average price based on prices ranging from $11.19 to $12.18.

⁶A weighted average price based on prices ranging from $12.30 to $12.37.

⁷A weighted average price based on prices ranging from $10.94 to $11.81.

⁸A weighted average price based on prices ranging from $10.71 to $10.84.

⁹A weighted average price based on prices ranging from $10.21 to $11.05.

¹⁰A weighted average price based on prices ranging from $10.28 to $10.31.

¹¹A weighted average price based on prices ranging from $10.10 to $10.74.

¹²A weighted average price based on prices ranging from $10.61 to $10.62.

¹³A weighted average price based on prices ranging from $10.53 to $10.85.

¹⁴A weighted average price based on prices ranging from $10.07 to $10.52.

¹⁵A weighted average price based on prices ranging from $9.85 to $10.65.

¹⁶A weighted average price based on prices ranging from $9.72 to $10.10.

Exhibit 2

POWER OF ATTORNEY

FOR CERTAIN REGULATORY FILINGS

INCLUDING CERTAIN FILINGS

UNDER THE SECURITIES EXCHANGE ACT OF 1934

AND THE INVESTMENT ADVISERS ACT OF 1940

I, David E. Shaw, hereby make, constitute, and appoint each of

Adam Deaton,

Anne Dinning,

Edward Fishman,

Alexis Halaby,

Edwin Jager,

Martin Lebwohl,

Daniel Marcus,

Anoop Prasad,

Maximilian Stone, and

David Sweet,

acting individually in such person’s capacity as an employee of D. E. Shaw & Co., L.P. or one of its subsidiaries, as my agent and attorney-in-fact, with full power of substitution, for the purpose of, from time to time, (i) executing in my name, in my capacity as President of D. E. Shaw & Co., Inc. (acting for itself or as the general partner of D. E. Shaw & Co., L.P. and general partner, managing member, or manager of other entities, any of which in turn may be acting for itself or other entities), all documents, certificates, instruments, statements, other filings, and amendments to the foregoing (collectively, “documents”) determined by such person to be necessary or appropriate to comply with any registration or regulatory disclosure requirements and/or ownership or control-person reporting requirements imposed by any U.S. or non-U.S. governmental or regulatory authority, including without limitation Form ADV, Forms 3, 4, 5, and 13F, and Schedules 13D and 13G required to be filed with the U.S. Securities and Exchange Commission, and/or (ii) delivering, furnishing, or filing, in each case whether themself or through their designee, any such documents to or with the appropriate governmental or regulatory authority.  Any such determination shall be conclusively evidenced by such person’s execution of, and/or their (or their designee’s) delivery, furnishing, and/or filing of, the applicable document.

This power of attorney shall be valid as of the date set forth below and replaces the power granted on March 1, 2017, which is hereby cancelled.  Furthermore, this power of attorney shall be valid with respect to any particular individual set forth above only for so long as such person remains employed by D. E. Shaw & Co., L.P. or one of its subsidiaries.

IN WITNESS HEREOF, I have executed this instrument as of the date set forth below.

Date:  August 1, 2024

/s/ David E. Shaw

David E. Shaw,

as President of D. E. Shaw & Co., Inc.

Exhibit 3

POWER OF ATTORNEY

FOR CERTAIN REGULATORY FILINGS

INCLUDING CERTAIN FILINGS

UNDER THE SECURITIES EXCHANGE ACT OF 1934

AND THE INVESTMENT ADVISERS ACT OF 1940

I, David E. Shaw, hereby make, constitute, and appoint each of

Adam Deaton,

Anne Dinning,

Edward Fishman,

Alexis Halaby,

Edwin Jager,

Martin Lebwohl,

Daniel Marcus,

Anoop Prasad,

Maximilian Stone, and

David Sweet,

acting individually in such person’s capacity as an employee of D. E. Shaw & Co., L.P. or one of its subsidiaries, as my agent and attorney-in-fact, with full power of substitution, for the purpose of, from time to time, (i) executing in my name, in my capacity as President of D. E. Shaw & Co. II, Inc. (acting for itself or as the managing member of D. E. Shaw & Co., L.L.C. and general partner, managing member, or manager of other entities, any of which in turn may be acting for itself or other entities), all documents, certificates, instruments, statements, other filings, and amendments to the foregoing (collectively, “documents”) determined by such person to be necessary or appropriate to comply with any registration or regulatory disclosure requirements and/or ownership or control-person reporting requirements imposed by any U.S. or non-U.S. governmental or regulatory authority, including without limitation Form ADV, Forms 3, 4, 5, and 13F, and Schedules 13D and 13G required to be filed with the U.S. Securities and Exchange Commission, and/or (ii) delivering, furnishing, or filing, in each case whether themself or through their designee, any such documents to or with the appropriate governmental or regulatory authority.  Any such determination shall be conclusively evidenced by such person’s execution of, and/or their (or their designee’s) delivery, furnishing, and/or filing of, the applicable document.

This power of attorney shall be valid as of the date set forth below and replaces the power granted on March 1, 2017, which is hereby cancelled.  Furthermore, this power of attorney shall be valid with respect to any particular individual set forth above only for so long as such person remains employed by D. E. Shaw & Co., L.P. or one of its subsidiaries.

IN WITNESS HEREOF, I have executed this instrument as of the date set forth below.

Date:  August 1, 2024

/s/ David E. Shaw

David E. Shaw,

as President of D. E. Shaw & Co. II, Inc.

Exhibit 4

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, each of the undersigned Reporting Persons hereby agrees to the joint filing, along with all other such Reporting Persons, on behalf of each of them of a statement on Schedule 13D (including amendments thereto) with respect to the Common Stock, $0.0001 par value per share, of Gossamer Bio, Inc., and that this Agreement be included as an Exhibit to such joint filing. This Agreement may be executed in any number of counterparts, all of which taken together shall constitute one and the same instrument.

IN WITNESS WHEREOF, each of the undersigned hereby executes this Agreement as of this 8th day of October, 2026.