Gossamer Bio: D. E. Shaw reports 4.2% ownership

Valence, D. E. Shaw & Co., L.L.C., D. E. Shaw & Co., L.P., and David E. Shaw ceased to be beneficial owners of more than 5% on October 27, 2026.

Rhea-AI Filing Summary

Gossamer Bio, Inc. (GOSS) is the subject of an amended beneficial-ownership disclosure by D. E. Shaw reporting persons. D. E. Shaw Valence Portfolios, L.L.C. reports beneficial ownership of 243,041 common shares, or approximately 4.0%; Cogence reports 12,390 shares, or approximately 0.2%. D. E. Shaw & Co., L.L.C. and D. E. Shaw & Co., L.P. each report shared voting and dispositive power over 255,431 shares, or 4.2%. David E. Shaw, President and sole shareholder of D. E. Shaw & Co., Inc. and D. E. Shaw & Co. II, Inc., may also be deemed to share that power but disclaims beneficial ownership. On October 27, 2026, Valence, D. E. Shaw & Co., L.L.C., D. E. Shaw & Co., L.P., and David E. Shaw ceased to be beneficial owners of more than 5%. The percentages use 6,116,391 common shares issued and outstanding as of September 14, 2026.

Key Figures

Valence beneficial ownership: 243,041 shares Cogence beneficial ownership: 12,390 shares Shared voting and dispositive power: 255,431 shares +4 more

7 metrics

Valence beneficial ownership 243,041 shares D. E. Shaw Valence Portfolios, L.L.C.

Cogence beneficial ownership 12,390 shares Cogence

Shared voting and dispositive power 255,431 shares Reported by D. E. Shaw & Co., L.L.C. and D. E. Shaw & Co., L.P.

Valence ownership percentage approximately 4.0% Percentage of outstanding common shares

Cogence ownership percentage approximately 0.2% Percentage of outstanding common shares

Reported ownership percentage 4.2% Reported by D. E. Shaw & Co., L.L.C. and D. E. Shaw & Co., L.P.

Common shares issued and outstanding 6,116,391 shares As of September 14, 2026

Key Terms

beneficial ownership, shared voting power, shared dispositive power, issued and outstanding

4 terms

beneficial ownership regulatory

"may be deemed to be the beneficial owner"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

shared voting power regulatory

"Shared Voting Power 255,431.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power regulatory

"Shared Dispositive Power 255,431.00"

issued and outstanding financial

"6,116,391 Common Shares issued and outstanding"

Issued and outstanding refers to two related counts of a company's stock: "issued" is the total number of shares the company has created and ever sold, while "outstanding" is the number of those shares currently held by outside investors (issued shares minus any the company holds in its treasury). Investors use outstanding shares to calculate ownership percentages, voting power, earnings per share and market capitalization — think of issued shares as all slices baked and outstanding as the slices actually on the table for people to eat.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many GOSS shares did D. E. Shaw-related entities report?

D. E. Shaw Valence Portfolios, L.L.C. reports beneficial ownership of 243,041 shares, and Cogence reports beneficial ownership of 12,390 shares. D. E. Shaw & Co., L.L.C. and D. E. Shaw & Co., L.P. each report shared voting and dispositive power over 255,431 shares.

What percentage of GOSS did the D. E. Shaw reporting persons report?

Valence is listed at approximately 4.0%, Cogence at approximately 0.2%, and D. E. Shaw & Co., L.L.C., D. E. Shaw & Co., L.P., and David E. Shaw at 4.2% each. The percentages are based on 6,116,391 common shares issued and outstanding as of September 14, 2026.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 10/29/2026 - 07:48 PM EDT Accepted by SEC EDGAR 10/29/2026 - 07:47 PM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 6)

Gossamer Bio, Inc.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

38341P201

(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)

10/27/2026

(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).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 38341P201

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 243,041.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 243,041.00

11

Aggregate amount beneficially owned by each reporting person

243,041.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.0 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s): 38341P201

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 255,431.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 255,431.00

11

Aggregate amount beneficially owned by each reporting person

255,431.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.2 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s): 38341P201

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 255,431.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 255,431.00

11

Aggregate amount beneficially owned by each reporting person

255,431.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.2 %

14

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP Number(s): 38341P201

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 255,431.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 255,431.00

11

Aggregate amount beneficially owned by each reporting person

255,431.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.2 %

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. 6 to Schedule 13D ("Amendment No. 6") is filed by and on behalf of each of the Reporting Persons to amend and supplement the Schedule 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 to Schedule 13D filed on July 1, 2026, Amendment No. 2 to Schedule 13D filed on July 24, 2026, Amendment No. 3 to Schedule 13D filed on August 24, 2026, Amendment No. 4 to Schedule 13D filed on September 28, 2026, and Amendment No. 5 to Schedule 13D filed on October 8, 2026 (as amended, the "Schedule 13D"). 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.
Item 5.	Interest in Securities of the Issuer
(a)	Item 5(a) of the Schedule 13D is hereby amended and restated as follows: 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. 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 243,041 Common Shares beneficially owned by Valence (the "Valence Shares") represent approximately 4.0% of the outstanding Common Shares. The 12,390 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 (and the power to dispose or direct the disposition of) the Valence Shares. Cogence has the power to vote or direct the vote of (and the power to dispose or direct the disposition 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, and the shared power to dispose or direct the disposition of, 255,431 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, and the shared power to dispose or direct the disposition of, 255,431 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, and the shared power to dispose or direct the disposition of, 255,431 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, and the shared power to dispose or direct the disposition of, 255,431 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, and the shared power to dispose or direct the disposition of, the 255,431 Common Shares as described above constituting 4.2% 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. 6.
(c)	Item 5(c) of the Schedule 13D is hereby amended and supplemented as follows: Schedule I to Amendment No. 6, 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. 5.
(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)	On October 27, 2026, Valence, DESCO LLC, DESCO LP, and David E. Shaw ceased to be the beneficial owners of more than 5 percent of the class of securities.
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. 5) 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 29, 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:	10/29/2026

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

Signature:	/s/ Daniel R. Marcus
Name/Title:	Daniel R. Marcus / Authorized Signatory
Date:	10/29/2026

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

Signature:	/s/ Daniel R. Marcus
Name/Title:	Daniel R. Marcus / Chief Compliance Officer
Date:	10/29/2026

David E. Shaw

Signature:	/s/ Daniel R. Marcus
Name/Title:	Daniel R. Marcus / Attorney-in-Fact for David E. Shaw
Date:	10/29/2026