Gossamer Bio SEC Filings

Christian Waage, Executive Vice President, Tech Ops and Admin at Gossamer Bio, Inc. (GOSS), received a performance stock unit award of 125,000 shares on 10/01/2025. The award has a $0 purchase price and will vest in full upon the earlier of (i) approval of a new drug application for seralutinib or (ii) a change in control, in either case on or before the fourth anniversary of the grant, subject to continuous service. Following the grant, Mr. Waage is reported to beneficially own 710,934 shares directly, plus 45,892 shares held by a family trust and 22,222 held in a trust for his son. The Form 4 was signed by an attorney-in-fact on 10/02/2025.

Gossamer Bio, Inc. (GOSS) Chief Operating and Financial Officer Bryan Giraudo reported an award of 181,250 performance stock units on 10/01/2025. The award is a non‑cash grant that will vest in full upon the earlier of: approval of a new drug application for seralutinib or a change in control, provided vesting occurs on or before the fourth anniversary of the grant and the reporting person remains in continuous service. Following the reported grant, Mr. Giraudo beneficially owns 273,987 shares directly and 480,010 shares indirectly through a family trust, for combined reported beneficial ownership disclosed on the form.

Richard Aranda, Chief Medical Officer of Gossamer Bio, Inc. (GOSS), reported receiving a performance stock unit award of 162,500 common stock units on 10/01/2025. The award carries a $0 purchase price and will vest in full upon the earlier of (i) approval of a new drug application for seralutinib or (ii) a change in control, provided vesting occurs on or before the fourth anniversary of the grant date and subject to the reporting person’s continuous service. After the reported transaction, the filing shows 369,356 shares beneficially owned directly and 2,539 shares beneficially owned indirectly through a family trust. The filing was signed by an attorney-in-fact on 10/02/2025.

Hasnain Faheem, President & CEO and a director of Gossamer Bio, Inc. (GOSS), reported a non‑derivative acquisition dated 10/01/2025 of 437,500 performance stock units at a reported price of $0. After the award, the filing shows 557,793 shares beneficially owned directly and 5,408,073 shares beneficially owned indirectly through a family trust. The performance stock units will vest in full upon the earlier of the approval of a new drug application for seralutinib or a change in control, in either case on or before the fourth anniversary of the grant date, and are subject to the reporting person’s continuous service to the issuer. The Form 4 was signed on 10/02/2025 by an attorney‑in‑fact.

Caryn Peterson, Executive Vice President, Regulatory Affairs of Gossamer Bio, Inc. (GOSS), reported the acquisition of 125,000 performance stock units on 10/01/2025. The award is a performance stock unit grant that vests in full upon the earlier of (i) approval of a new drug application for seralutinib or (ii) a change in control, in either case on or before the fourth anniversary of the grant date, and is subject to the reporting person’s continuous service. After the transaction the reporting person beneficially owns 174,833 shares. The Form 4 was signed by an attorney-in-fact on 10/02/2025.

Gossamer Bio, Inc. issued 2,500,000 shares of common stock to Prana on September 24, 2025 as consideration for a Company Merger Option. The Company agreed that, upon exercise of the Merger Option at closing, it would issue up to an additional 1,500,000 shares. The agreement also provides for cash and stock milestone payments following achievement of specified regulatory and sales milestones, including potential issuance of up to approximately 6,688,964 additional shares of common stock. The number of milestone shares to be issued will be calculated by dividing the applicable milestone obligation value by the average closing price on the Nasdaq Global Select Market for the thirty consecutive trading days ending two trading days before achievement of the milestone. The transactions are being made in reliance on Section 4(a)(2) of the Securities Act of 1933.

Sandra Milligan, a director of Gossamer Bio, purchased 26,050 shares of the company's common stock on 08/19/2025 at $1.92 per share, increasing her beneficial ownership to 58,050 shares. The transaction is reported on a Form 4 covering non-derivative securities. The filing indicates the purchase was reported individually by the reporting person.