Richard Aranda - 01 Oct 2025 Form 4 Insider Report for Gossamer Bio, Inc. (GOSS)

Role: Chief Medical Officer
Signature: /s/ Jeff Boerneke, Attorney-in-Fact
Issuer symbol: GOSS
Transactions as of: 01 Oct 2025
Net transactions value: $0
Form type: 4
Filing time: 02 Oct 2025, 16:13:26 UTC
Previous filing: 06 Mar 2025
Next filing: 05 Jan 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Aranda Richard	Chief Medical Officer	3115 MERRYFIELD ROW, SUITE 120, SAN DIEGO	/s/ Jeff Boerneke, Attorney-in-Fact	02 Oct 2025	0001867872

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	GOSS	Common Stock	Award	$0	+162,500	+79%	$0.000000	369,356	01 Oct 2025	Direct	F1
holding	GOSS	Common Stock						2,539	01 Oct 2025	By family trust

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Represents performance stock unit award, which will vest in full upon the earlier of (i) the approval of a new drug application for seralutinib or (ii) a change in control, in either case on or prior to the fourth anniversary of the grant date, and subject to the Reporting Person's continuous service to the Issuer.