Gossamer Bio Announces Inducement Grant Under Nasdaq Listing Rule 5635

Gossamer Bio, Inc. (Nasdaq: GOSS), a late-stage, clinical biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH-ILD), today announced that the Compensation Committee of Gossamer's Board of Directors approved the grant, effective September 5 ^th , 2025, to two non-executive employees of non-qualified stock option awards to purchase up to an aggregate of 87,500 shares of the Company's common stock under the Gossamer Bio, Inc. 2023 Employment Inducement Incentive Award Plan ("2023 Inducement Plan"). The awards were granted as an inducement material to the employees entering into employment with Gossamer in accordance with Nasdaq Listing Rule 5635(c)(4).

The options have an exercise price of $2.94 per share, which is equal to the closing price of Gossamer's common stock as reported by The Nasdaq Global Select Market on September 5 ^th , 2025. The options have a ten-year term and will vest over four years, with 25% vesting on the one-year anniversary of the applicable vesting commencement date and the balance of the shares vesting in a series of 36 successive monthly installments thereafter, subject to the employees' continued employment with Gossamer on such vesting dates. The options are subject to the terms and conditions of the 2023 Inducement Plan and the terms and conditions of a stock option agreement covering the grants.

About Gossamer Bio

Gossamer Bio is a late-stage, clinical biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease. Its goal is to be an industry leader in, and to enhance the lives of patients living with, pulmonary hypertension.

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For Investors and Media:
Bryan Giraudo, Chief Operating Officer and Chief Financial Officer
Gossamer Bio Investor Relations
ir@gossamerbio.com