683 Capital reports 49.87M-share position in Gossamer Bio (NASDAQ: GOSS)

Rhea-AI Filing Summary

683 Capital Management, 683 Capital Partners and Ari Zweiman report beneficial ownership totaling 49,868,571 shares of Gossamer Bio. The figure includes 39,504,484 shares of Common Stock, 9,102,055 currently exercisable warrants, and 1,262,032 shares issuable upon conversion of convertible notes.

The filing states this position represents approximately 9.99% of Common Stock on a basis that uses 488,846,722 shares outstanding as of June 5, 2026 plus the currently exercisable warrants and specified convertible-note issuances; the calculation is subject to a 9.99% beneficial ownership limitation in the relevant indenture.

Insights

Institutional Ownership Analyst

Large coordinated holding by an affiliated investment manager reaches the 9.99% threshold.

The filing discloses 49,868,571 shares beneficially owned including 9,102,055 exercisable warrants and 1,262,032 convertible-note issuable shares, using the issuer's June 5, 2026 outstanding share figure as the anchor. The percentage is reported as 9.99%.

Beneficial ownership is shown for 683 Capital Partners, LP with 683 Capital Management, LLC as manager and Ari Zweiman as managing member; the filing notes an indenture 9.99% limitation that constrains conversion/exercise impacts.

Corporate Governance Expert

Disclosure follows Schedule 13G joint-filing practice and clarifies shared voting/dispositive power.

The schedule lists shared voting and dispositive power of 49,868,571 shares across the Reporting Persons and attaches a joint filing agreement signed by Ari Zweiman on June 11, 2026. The statement references the issuer's proxy for the outstanding share count.

Key dependencies include treatment of exercisable warrants and convertible-note conversions when assessing any future change above the reported 9.99% threshold; timing and holder decisions will determine any subsequent reporting changes.

Key Figures

Beneficially owned shares: 49,868,571 shares Common Stock held: 39,504,484 shares Exercisable warrants: 9,102,055 shares +3 more

6 metrics

Beneficially owned shares 49,868,571 shares As of June 11, 2026; includes warrants and convertible-note issuable shares

Common Stock held 39,504,484 shares Counted as direct/common shares in the beneficial ownership disclosure

Exercisable warrants 9,102,055 shares Warrants currently exercisable included in beneficial ownership total

Convertible-note issuable shares 1,262,032 shares Shares issuable upon conversion of convertible notes included in total

Shares outstanding used 488,846,722 shares Outstanding common shares as of <date>June 5, 2026</date> per issuer proxy

Reported ownership percentage 9.99% Calculated basis includes outstanding shares plus exercisable warrants and specified convertible-note issuances

Key Terms

exercisable warrants, convertible notes, beneficial ownership limitation

3 terms

exercisable warrants financial

"the amounts reflected ... (b) 9,102,055 shares of Common Stock issuable upon exercise of warrants currently exercisable"

convertible notes financial

"1,262,032 shares of Common Stock issuable upon conversion of convertible notes"

Convertible notes are a type of short-term loan that a company receives from investors, which can later be turned into company shares instead of being paid back in cash. They matter to investors because they offer a way to support a company early on while giving the potential to own a stake in its success if the company grows and later raises more funding.

beneficial ownership limitation regulatory

"excludes shares ... in excess of the 9.99% beneficial ownership limitation contained in the indenture"

A beneficial ownership limitation is a rule that caps the percentage of a company’s shares an investor can be treated as owning or controlling for voting, regulatory or tax purposes. It matters to investors because it can restrict how many shares a person or group can buy or vote, affect takeover chances, and influence share liquidity and value — like a speed limit that prevents any single driver from taking over the whole road.

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Available on EDGAR 06/11/2026 - 04:55 PM Accepted by SEC EDGAR 06/11/2026 - 04:54 PM Learn about SEC filing dates

FAQ

How many Gossamer Bio (GOSS) shares does 683 Capital beneficially own?

They report beneficial ownership of 49,868,571 shares including warrants and convertible conversions. The filing breaks this into 39,504,484 common shares, 9,102,055 exercisable warrants, and 1,262,032 shares from convertible notes.

What percentage of Gossamer Bio does the 49,868,571 position represent?

The Reporting Persons state the position equals approximately 9.99% of the common stock on the disclosed basis. That percentage uses 488,846,722 shares outstanding as of June 5, 2026 plus specified exercisable warrants and convertible-note issuances.

Do the reported holdings include derivatives or convertible instruments?

Yes. The filing explicitly includes 9,102,055 currently exercisable warrants and 1,262,032 shares issuable upon conversion of convertible notes in the beneficial ownership calculation. The schedule notes a 9.99% indenture limitation on conversions.

Who are the Reporting Persons in this Schedule 13G filing for GOSS?

The Reporting Persons are 683 Capital Management, LLC; 683 Capital Partners, LP; and Ari Zweiman. The filing lists 683 Capital Management as investment manager and Ari Zweiman as Managing Member and signatory on the joint filing agreement.

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

(Title of Class of Securities)

38341P102

(CUSIP Number)

06/04/2026

(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)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 38341P102

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 49,868,571.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 49,868,571.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

49,868,571.00

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)

9.99 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: The amounts reflected in Rows 5-9 include (a) 39,504,484 shares of Common Stock, (b) 9,102,055 shares of Common Stock issuable upon exercise of warrants currently exercisable, and (c) 1,262,032 shares of Common Stock issuable upon conversion of convertible notes.

SCHEDULE 13G

CUSIP Number(s): 38341P102

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 49,868,571.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 49,868,571.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

49,868,571.00

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)

9.99 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: The amounts reflected in Rows 5-9 include (a) 39,504,484 shares of Common Stock, (b) 9,102,055 shares of Common Stock issuable upon exercise of warrants currently exercisable, and (c) 1,262,032 shares of Common Stock issuable upon conversion of convertible notes.

SCHEDULE 13G

CUSIP Number(s): 38341P102

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 49,868,571.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 49,868,571.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

49,868,571.00

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)

9.99 %

12

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person: The amounts reflected in Rows 5-9 include (a) 39,504,484 shares of Common Stock, (b) 9,102,055 shares of Common Stock issuable upon exercise of warrants currently exercisable, and (c) 1,262,032 shares of Common Stock issuable upon conversion of convertible notes.

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 Each of the foregoing is referred to as a "Reporting Person" and collectively as the "Reporting Persons."
(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
(e)	CUSIP Number(s): 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 June 11, 2026, 683 Capital Partners, LP beneficially owned (a) 49,868,571 shares of Common Stock, (b) warrants to purchase 9,102,055 shares of Common Stock which are currently exercisable, and (c) 1,262,032 shares issuable upon conversion of convertible notes. 683 Capital Management, LLC, as the investment manager of 683 Capital Partners, LP, may be deemed to have beneficially owned the (a) 49,868,571 shares of Common Stock, (b) warrants to purchase 9,102,055 shares of Common Stock which are currently exercisable, and (c) 1,262,032 shares issuable upon conversion of convertible notes 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 (a) 49,868,571 shares of Common Stock, (b) warrants to purchase 9,102,055 shares of Common Stock which are currently exercisable, and (c) 1,262,032 shares issuable upon conversion of convertible notes beneficially owned by 683 Capital Partners, LP. beneficially owned by 683 Capital Management, LLC. The following percentage is based on 488,846,722 shares of common stock ($0.0001 par value) outstanding as of June 5, 2026, as disclosed in the Issuer's Form DEF 14A filed on June 9, 2026, plus (a) 9,102,055 shares of Common Stock issuable upon exercise of currently exercisable warrants and (b) 1,262,032 shares issuable upon conversion of convertible notes, but excludes shares of Common Stock issuable upon conversion of convertible notes in excess of the 9.99% beneficial ownership limitation contained in the indenture governing such notes. As of June 11, 2026, the Reporting Persons may be deemed to have beneficially owned approximately 9.99% of the outstanding Common Shares.
(b)	Percent of class: 9.99 %
(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:	06/11/2026

683 Capital Partners, LP

Signature:	Ari Zweiman
Name/Title:	Authorized Person
Date:	06/11/2026

Ari Zweiman

Signature:	Ari Zweiman
Name/Title:	Self
Date:	06/11/2026

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 June 11, 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: June 11, 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