683 Capital reports 5.23% stake in Gossamer Bio

683 Capital Management, LLC and related reporting persons reported beneficial ownership in Gossamer Bio.

Rhea-AI Filing Summary

683 Capital Management, LLC and related reporting persons reported beneficial ownership in Gossamer Bio. As of March 2, 2026, the reporting persons beneficially owned 8,000,000 shares of common stock plus warrants exercisable for 4,331,304 shares, totaling 12,331,304 shares, or 5.23% of common stock on the basis described in the filing. The filing states the 4,331,304 warrants are currently exercisable and that voting and dispositive power over these securities is shared among the reporting persons.

The percentage uses an outstanding share base of 231,456,247 common shares as of October 31, 2025, plus the 4,331,304 exercisable-warrant shares, per the disclosure.

Insights

Institutional Ownership Analyst

Large holder reports a 5.23% stake including exercisable warrants.

The filing discloses beneficial ownership of 8,000,000 common shares plus warrants exercisable for 4,331,304 shares, totaling 12,331,304 shares as of March 2, 2026. The percentage is calculated using 231,456,247 shares outstanding as of October 31, 2025 plus the exercisable warrants, per the filing.

Holder control is described as shared voting and dispositive power. The filing is a standard beneficial-ownership disclosure and does not itself change holdings; subsequent Form 4s would report transactions if shares or warrants are traded or exercised.

Governance & Compliance Specialist

Joint filing and manager attribution clarify reporting relationships.

The Schedule 13G lists 683 Capital Partners, LP as direct beneficial owner and 683 Capital Management, LLC and Ari Zweiman as attributable via management roles; a Joint Filing Agreement is attached and signed on March 2, 2026. The filing ties beneficial ownership to currently exercisable warrants of 4,331,304 shares.

Voting and dispositive power are reported as shared on the cover pages. This is a compliance disclosure under securities rules; it documents positions and attributions rather than announcing a transaction.

FAQ

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

What stake does 683 Capital report in GOSS?

The reporting persons state beneficial ownership of 12,331,304 shares including exercisable warrants. This equals 5.23% of common stock on the stated basis in the filing.

How is the 12,331,304 total constructed in the filing?

The total combines 8,000,000 directly beneficial shares and warrants exercisable for 4,331,304 shares; the filing describes the warrants as currently exercisable as of March 2, 2026.

What share count did the filing use to calculate the percentage?

The percentage is based on 231,456,247 shares outstanding as of October 31, 2025 from the issuer's Form 10-Q, plus the 4,331,304 exercisable-warrant shares, per the filing.

Who is reported as having voting and dispositive power?

The cover pages indicate shared voting and shared dispositive power over the 12,331,304 shares; the filing attributes control among 683 Capital Partners, 683 Capital Management, LLC, and Ari Zweiman.

Does the filing show any transactions or changes in holdings?

This Schedule 13G is a beneficial-ownership disclosure dated March 2, 2026 and describes positions and attribution; it does not report open-market buy/sell transactions within this excerpt.

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

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Accepted by SEC EDGAR 03/02/2026 - 11:57 AM Learn about SEC filing dates

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, $0.0001 par value per share

(Title of Class of Securities)

02/23/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP Number(s):

1

Names of Reporting Persons

683 Capital Management, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 12,331,304.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 12,331,304.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

12,331,304.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.23 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP Number(s):

1

Names of Reporting Persons

683 Capital Partners, LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 12,331,304.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 12,331,304.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

12,331,304.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.23 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s):

1

Names of Reporting Persons

Ari Zweiman

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 12,331,304.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 12,331,304.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

12,331,304.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.23 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Gossamer Bio, Inc.
(b)	Address of issuer's principal executive offices: 3115 MERRYFIELD ROW, SUITE 120, SAN DIEGO, CALIFORNIA 92121
Item 2.
(a)	Name of person filing: 683 Capital Management, LLC 683 Capital Partners, LP Ari Zweiman
(b)	Address or principal business office or, if none, residence: The principal business address for each of the Reporting Persons is 1700 Broadway, Suite 4200, New York, New York 10019.
(c)	Citizenship: 683 Capital Management, LLC - DELAWARE 683 Capital Partners, LP - DELAWARE Ari Zweiman - UNITED STATES
(d)	Title of class of securities: Common Stock, $0.0001 par value per share
(e)	CUSIP No.: 38341P102
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: As of March 2, 2026, 683 Capital Partners, LP beneficially owned 8,000,000 shares of Common Stock and warrants to purchase 4,331,304 shares of Common Stock which are currently exercisable. 683 Capital Management, LLC, as the investment manager of 683 Capital Partners, LP, may be deemed to have beneficially owned the 8,000,000 shares of Common Stock and warrants to purchase 4,331,304 shares of Common Stock beneficially owned by 683 Capital Partners, LP. Ari Zweiman, as the Managing Member of 683 Capital Management, LLC, may be deemed to have beneficially owned the 8,000,000 shares of Common Stock and warrants to purchase 4,331,304 shares of Common Stock beneficially owned by 683 Capital Management, LLC. The following percentage is based on 231,456,247 shares of common stock ($0.0001 par value) outstanding as of October 31, 2025, as disclosed in the Issuer's Form 10-Q filed on November 5, 2025, plus 4,331,304 shares of Common Stock issuable upon exercise of currently exercisable warrants held by the Reporting Persons. As of March 2, 2026, the Reporting Persons may be deemed to have beneficially owned approximately 5.23% of the outstanding Common Shares.
(b)	Percent of class: 5.23 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See Cover Pages Items 5-9.
	(ii) Shared power to vote or to direct the vote: See Cover Pages Items 5-9.
	(iii) Sole power to dispose or to direct the disposition of: See Cover Pages Items 5-9.
	(iv) Shared power to dispose or to direct the disposition of: See Cover Pages Items 5-9.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(K), so indicate under Item 3(k) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group. See Exhibit A.
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

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.

683 Capital Management, LLC

Signature:	Ari Zweiman
Name/Title:	Managing Member
Date:	03/02/2026

683 Capital Partners, LP

Signature:	Ari Zweiman
Name/Title:	Authorized Person
Date:	03/02/2026

Ari Zweiman

Signature:	Ari Zweiman
Name/Title:	Self
Date:	03/02/2026

Exhibit Information

JOINT FILING AGREEMENT The undersigned hereby agree that the statement on Schedule 13G with respect to the shares of Common Stock, par value $0.0001 per share, of Gossamer Bio, Inc. dated as of March 2, 2026 is, and any further amendments thereto signed by each of the undersigned shall be, filed on behalf of each of the undersigned pursuant to and in accordance with the provisions of Rule 13d-1(k)(2) under the Securities Exchange Act of 1934, as amended. Dated: March 2, 2026 683 CAPITAL MANAGEMENT, LLC By: /s/ Ari Zweiman Ari Zweiman, Managing Member 683 CAPITAL PARTNERS, LP By: /s/ Ari Zweiman Ari Zweiman, Authorized Person /s/ Ari Zweiman Ari Zweiman