Gossamer Bio CDO granted 5.8M options at $0.175

Gossamer Bio, Inc. (GOSS) reported a Form 4 for Chief Development Officer Caryn Peterson showing a grant of stock options for 5,800,051 shares of common stock on 2026-08-24, at an exercise price of $0.175 per share, expiring on 2036-08-23.

Rhea-AI Filing Summary

Gossamer Bio, Inc. (GOSS) reported a Form 4 for Chief Development Officer Caryn Peterson showing a grant of stock options for 5,800,051 shares of common stock on 2026-08-24, at an exercise price of $0.175 per share, expiring on 2036-08-23.

According to the vesting terms, 50% of the option vests upon FDA approval of seralutinib. The remaining 50% then vests in 24 equal monthly installments after that approval, subject to continued service. If FDA approval has not occurred within two years of the grant date, the entire option instead vests in 24 equal monthly installments starting two years after the grant date, also subject to continued service.

Insider Trade Summary

Grant/Award: 5,800,051 shares

Grant/Award 1 txn

Insider Peterson Caryn

Role Chief Development Officer

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy) F1	5,800,051	$0.00	$0.00

Holdings After Transaction: Stock Option (Right to Buy) — 5,800,051 contracts (Direct)

Footnotes (1)

1. F1. 50% of the total number of shares subject to the option will vest upon FDA approval of seralutinib, and 1/24th of the remaining 50% of the total number of shares subject to the option will vest on the last day of each one-month period after such FDA approval, in each case subject to the Reporting Person's continuous service to the Issuer on each such vesting date. To the extent FDA approval of seralutinib does not occur on or prior to the date that is two years following the grant date of the option, 1/24th of the total number of shares subject to the option will vest on the last day of each one-month period following the date that is two years following the grant date of the option, subject to the Reporting Person's continuous service to the Issuer on each such vesting date.

Key Figures

Option shares granted: 5,800,051 shares Exercise price: $0.175 per share Underlying common shares: 5,800,051 shares +4 more

7 metrics

Option shares granted 5,800,051 shares Stock Option (Right to Buy) granted on 2026-08-24

Exercise price $0.175 per share Conversion or exercise price for the stock option

Underlying common shares 5,800,051 shares Common Stock underlying the option

Expiration date 2036-08-23 Expiration of the stock option grant

Vesting on FDA approval 50% of option shares Vests upon FDA approval of seralutinib, subject to continuous service

Post-approval vesting installments 24 installments 1/24th of remaining 50% vests monthly after FDA approval

Alternative vesting start Two years after grant date If FDA approval has not occurred by then, vesting begins monthly over 24 months

Key Terms

Stock Option (Right to Buy, underlying security, vesting, FDA approval, +1 more

5 terms

Stock Option (Right to Buy financial

"security_title": "Stock Option (Right to Buy"

underlying security financial

"underlying_security_title": "Common Stock"

vesting financial

"shares subject to the option will vest upon FDA approval"

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

FDA approval medical

"will vest upon FDA approval of seralutinib"

FDA approval is the U.S. Food and Drug Administration’s formal authorization for a drug, vaccine, or medical device to be marketed and sold after reviewers determine it meets standards for safety and effectiveness. For investors it’s a pivotal milestone because it opens the door to legal, large-scale sales and can sharply boost revenue potential while reducing regulatory uncertainty—like receiving a safety certificate that lets a new bridge carry traffic and tolls.

continuous service financial

"subject to the Reporting Person's continuous service to the Issuer"

FAQ

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

Who received the stock option grant reported for GOSS?

The grant was reported for Caryn Peterson, who serves as Chief Development Officer of Gossamer Bio, Inc. The Form 4 lists her as an officer of the company, not a director and not a ten percent owner.

How many shares are covered by the new GOSS stock option grant?

The stock option grant covers 5,800,051 shares of Gossamer Bio, Inc. common stock. The Form 4 also shows that Ms. Peterson held a total of 5,800,051 option shares following this transaction, all from this award.

What is the exercise price of the stock options granted in this GOSS Form 4?

The options reported carry an exercise price of $0.175 per share. This price applies to the 5,800,051 shares underlying the stock option described as a “Stock Option (Right to Buy)” in the Form 4.

When do the newly granted GOSS options expire?

The options are scheduled to expire on 2036-08-23. This expiration date applies to the full 5,800,051 shares underlying the stock option grant reported in the Form 4 filing.

How do the GOSS options vest if seralutinib receives FDA approval?

If seralutinib receives FDA approval, 50% of the option vests at that time. The remaining 50% then vests in 24 equal monthly installments after approval, with each vesting date conditioned on Ms. Peterson’s continuous service.

How do the GOSS options vest if FDA approval of seralutinib is delayed more than two years?

If FDA approval has not occurred within two years after the grant date, the entire option vests instead in 24 equal monthly installments beginning after that two-year point, again subject to Ms. Peterson’s continuous service on each vesting date.

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

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Available on EDGAR 08/26/2026 - 06:13 PM EDT Accepted by SEC EDGAR 08/26/2026 - 06:12 PM EDT Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Peterson Caryn

(Last) (First) (Middle)

3115 MERRYFIELD ROW, SUITE 120

(Street)

SAN DIEGO CALIFORNIA 92121

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Gossamer Bio, Inc. [ GOSS ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Development Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/24/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	$0.175	08/24/2026		A		5,800,051		(1)	08/23/2036	Common Stock	5,800,051	$0	5,800,051	D

Explanation of Responses:

1. 50% of the total number of shares subject to the option will vest upon FDA approval of seralutinib, and 1/24th of the remaining 50% of the total number of shares subject to the option will vest on the last day of each one-month period after such FDA approval, in each case subject to the Reporting Person's continuous service to the Issuer on each such vesting date. To the extent FDA approval of seralutinib does not occur on or prior to the date that is two years following the grant date of the option, 1/24th of the total number of shares subject to the option will vest on the last day of each one-month period following the date that is two years following the grant date of the option, subject to the Reporting Person's continuous service to the Issuer on each such vesting date.

Remarks:

	/s/ Jeff Boerneke, Attorney-in-Fact	08/26/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)