Bryan Giraudo - 24 Aug 2026 Form 4 Insider Report for Gossamer Bio, Inc. (GOSS)

Reporting relationship: COO/CFO
Issuer ticker: GOSS
Reported as of: 24 Aug 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 26 Aug 2026, 18:10:18 UTC
Prior SEC filing: 11 May 2026
Source filing: View source filing
Reporting owner signature: /s/ Jeff Boerneke, Attorney-in-Fact

Key filing fact

Bryan Giraudo filed Form 4 for Gossamer Bio, Inc. (GOSS) on 26 Aug 2026.

Key facts

This page summarizes Bryan Giraudo's Form 4 filing for Gossamer Bio, Inc. (GOSS).
2 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 26 Aug 2026, 18:10.

Change

Previous filing in this sequence was filed on 11 May 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001740847 Primary reporting owner

Giraudo Bryan

Relationship: COO/CFO
Address: 3115 MERRYFIELD ROW, SUITE 120, SAN DIEGO
Signature: /s/ Jeff Boerneke, Attorney-in-Fact
Signature date: 26 Aug 2026

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

GOSS transaction Derivative

Pre-Funded Warrant (Right to Buy)

Award

Transaction value
Shares: +25
Change %
Price: $1000.00^*
Shares after: 25
Date: 24 Aug 2026
Ownership: By Family Trust
Underlying class: Series A-1 Preferred Stock
Underlying amount: 25
Exercise price: $0.000100
Footnotes: F1, F2

GOSS transaction Derivative

Stock Option (Right to Buy)

Award

Transaction value
Shares: +5,800,051
Change %
Price: $0.000000^*
Shares after: 5,800,051
Date: 24 Aug 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 5,800,051
Exercise price: $0.1750
Footnotes: F3

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 3 footnotes

Footnote F1

Each share of Series A-1 non-voting convertible preferred stock is convertible automatically upon receipt of stockholder approval under applicable Nasdaq rules and regulations in connection with the Issuer's private placement pursuant to which the Pre-Funded Warrants were issued ("Stockholder Approval") into a number of shares of the Issuer's common stock equal to $1,000 divided by $0.14, pursuant to the terms of the Series A-1 Certificate of Designation and subject to applicable beneficial ownership limitations.

Footnote F2

The Pre-Funded Warrant has no expiration date and is exercisable immediately. Prior to the Issuer obtaining Stockholder Approval, the Pre-Funded Warrants are only exercisable for shares of Series A-1 non-voting convertible preferred stock. Following the Issuer's receipt of Stockholder Approval, the Pre-Funded Warrants are only exercisable for shares of the Issuer's common stock.

Footnote F3

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.