Octagon reports 8.98M shares of Gossamer Bio

Gossamer Bio, Inc. Schedule 13G/A reports that Octagon-related reporting persons beneficially own 8,976,054 common shares, representing 3.8% of the class.

Rhea-AI Filing Summary

Gossamer Bio, Inc. Schedule 13G/A reports that Octagon-related reporting persons beneficially own 8,976,054 common shares, representing 3.8% of the class. The filing states the calculation is based on 234,696,281 shares outstanding as of March 10, 2026, plus 1,226,504 shares issuable upon exercise of warrants.

The ownership position is reported as shared voting and dispositive power. The filing discloses that the position includes 7,750,000 directly held common shares and warrants to purchase up to 1,226,054 shares (exercise price $2.04, expiration July 24, 2028).

Insights

Institutional Ownership Analyst

Octagon reports a 3.8% stake in Gossamer Bio totaling 8.98M shares.

Octagon and affiliated entities collectively report beneficial ownership of 8,976,054 shares, shown as shared voting and dispositive power. The position mixes 7,750,000 directly held shares and 1,226,054 warrants exercisable at $2.04 until July 24, 2028.

Future activity depends on whether warrants are exercised; transactions would be subject to warrant terms and market conditions. Subsequent filings would show any exercises or sales.

Securities Compliance Counsel

Filing is a joint Schedule 13G/A disclosure showing shared control through Octagon and its Master Fund.

The statement clarifies relationships: Octagon is investment manager, the Master Fund holds the shares for investors, and Dr. Ting Jia is a managing member. The reported percentage is calculated using the issuer's Form 10-K share count as of March 10, 2026.

The filing attributes shared voting/dispositive power; any change in ownership or warrant exercise should be reflected in amended Section 13 reports as required by the Exchange Act.

Key Figures

Beneficially owned: 8,976,054 shares Percent of class: 3.8% Shares outstanding (anchor): 234,696,281 shares +2 more

5 metrics

Beneficially owned 8,976,054 shares reported on Schedule 13G/A

Percent of class 3.8% based on shares outstanding as of March 10, 2026

Shares outstanding (anchor) 234,696,281 shares as of <date>March 10, 2026</date> (Form 10-K)

Warrants exercisable 1,226,054 shares exercise price $2.04, expires <date>July 24, 2028</date>

Directly held common shares 7,750,000 shares included in the reported position

Key Terms

Schedule 13G/A, Warrants, Shared dispositive power, Beneficial ownership

4 terms

Schedule 13G/A regulatory

"This statement is being jointly filed by: Octagon Capital Advisors"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

Warrants financial

"warrants to purchase up to 1,226,054 Common Shares"

Warrants are special documents that give you the right to buy a company's stock at a set price before a certain date. They are often used as a way for companies to attract investors or raise money, and their value can increase if the company's stock price goes up.

Shared dispositive power regulatory

"Shared Dispositive Power 8,976,054.00"

Beneficial ownership regulatory

"Amount beneficially owned: 8,976,054"

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.

FAQ

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

What stake does Octagon report in Gossamer Bio (GOSS)?

Octagon reports beneficial ownership of 8,976,054 shares, equal to 3.8% of the class. The percentage uses 234,696,281 shares outstanding as of March 10, 2026, plus 1,226,504 shares issuable on warrants.

How is the 8,976,054-share position composed?

The position includes 7,750,000 directly held common shares and warrants to purchase up to 1,226,054 shares. The warrants have an exercise price of $2.04 and expire on July 24, 2028.

Who are the reporting persons named in the 13G/A?

The statement is jointly filed by Octagon Capital Advisors LP, Octagon Investments Master Fund LP, and Ting Jia as principal beneficial owner and managing member of Octagon.

What voting and disposition powers are reported?

The filing reports 0 sole voting power and 8,976,054 shared voting power, and the same split for dispositive power, indicating shared control over voting and disposition of the shares.

How was the ownership percentage calculated?

The percentage is calculated using 234,696,281 shares outstanding as of March 10, 2026 from the issuer's Form 10-K, plus 1,226,504 Common Shares issuable upon exercise of the warrants.

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

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Accepted by SEC EDGAR 05/14/2026 - 04:01 PM EDT Learn about SEC filing dates

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, $0.0001 par value

(Title of Class of Securities)

38341P102

(CUSIP Number)

03/31/2026

(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

Octagon Capital Advisors 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 8,976,054.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 8,976,054.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

8,976,054.00

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)

3.8 %

12

Type of Reporting Person (See Instructions)

IA, PN

Comment for Type of Reporting Person: Includes 7,750,000 Common Shares directly held and warrants (the "Warrants") to purchase up to 1,226,054 Common Shares, with an exercise price of $2.04 per Common Share and an expiration date of July 24, 2028.

SCHEDULE 13G

CUSIP Number(s): 38341P102

1

Names of Reporting Persons

Octagon Investments Master Fund 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

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 8,976,054.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 8,976,054.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

8,976,054.00

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)

3.8 %

12

Type of Reporting Person (See Instructions)

PN, OO

Comment for Type of Reporting Person: Includes 7,750,000 Common Shares directly held and Warrants to purchase up to 1,226,054 Common Shares, with an exercise price of $2.04 per Common Share and an expiration date of July 24, 2028.

SCHEDULE 13G

CUSIP Number(s): 38341P102

1

Names of Reporting Persons

Ting Jia

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

CHINA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 8,976,054.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 8,976,054.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

8,976,054.00

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)

3.8 %

12

Type of Reporting Person (See Instructions)

HC, IN

Comment for Type of Reporting Person: Includes 7,750,000 Common Shares directly held and Warrants to purchase up to 1,226,054 Common Shares, with an exercise price of $2.04 per Common Share and an expiration date of July 24, 2028.

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, CA, 92121
Item 2.
(a)	Name of person filing: This statement is being jointly filed by: Octagon Capital Advisors LP ("Octagon") Octagon Investments Master Fund LP ("Master Fund") Ting Jia, as the principal beneficial owner of Octagon ("Dr. Jia") Each of the foregoing is referred to as a "Reporting Person" and collectively as the "Reporting Persons." Octagon serves as the investment manager of the Master Fund. Dr. Jia is the managing member of Octagon. By virtue of these relationships each of Octagon and Dr. Jia may be deemed to beneficially own the Issuer's Common Shares directly owned by the Master Fund.
(b)	Address or principal business office or, if none, residence: The address of the business office of each of the Reporting Persons is 654 Madison Avenue, 21st Floor, New York, NY 10065.
(c)	Citizenship: Octagon is a Delaware limited partnership. The Master Fund is an exempted limited partnership established in the Cayman Islands. Dr. Jia is a Chinese citizen.
(d)	Title of class of securities: Common Stock, $0.0001 par value
(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: 8,976,054
(b)	Percent of class: 3.8 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 8,976,054
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 8,976,054 The percentage reported on this Schedule 13G is calculated based upon 234,696,281 Common Shares outstanding as of March 10, 2026, as reported in the Form 10-K filed by the Issuer on March 17, 2026, plus 1,226,504 Common Shares issuable upon exercise of the Warrants.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. Octagon is the investment advisor to the Master Fund and other accounts. Dr. Jia is the control person of Octagon. The Master Fund holds the Common Shares for the benefit of its investors. The Master Fund and Octagon, for the benefit of its investors, have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Common Shares.
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.
	Not Applicable
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 acquired and are held in the ordinary course of business and 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.

Octagon Capital Advisors LP

Signature:	/s/ Ting Jia
Name/Title:	Managing Member
Date:	05/14/2026

Octagon Investments Master Fund LP

Signature:	/s/ Ting Jia
Name/Title:	Managing Member, Octagon Investments GP, LLC, its general partner
Date:	05/14/2026

Ting Jia

Signature:	/s/ Ting Jia
Name/Title:	Ting Jia
Date:	05/14/2026