Common Stock, $0.0001 par value per share

Gossamer Bio, Inc.

3115 Merryfield Row, San Diego, CA, 92121

Growth Equity Opportunities 18 VGE, LLC ("GEO"); NEA 18 Venture Growth Equity, L.P. ("NEA 18 VGE"), which is the sole member of GEO; NEA Partners 18 VGE, L.P. ("NEA Partners 18 VGE"), which is the sole general partner of NEA 18 VGE; and NEA 18 VGE GP, LLC ("NEA 18 VGE LLC" and, together with NEA Partners 18 VGE, the "Control Entities"), which is the sole general partner of NEA Partners 18 VGE; and Ali Behbahani ("Behbahani"), Carmen Chang ("Chang"), Anthony A. Florence, Jr. ("Florence"), Mohamad H. Makhzoumi ("Makhzoumi"), Edward T. Mathers ("Mathers"), Scott D. Sandell ("Sandell"), Paul Walker ("Walker") and Rick Yang ("Yang") (together, the "Managers"). The Managers are the managers of NEA 18 VGE LLC. The persons named in this Item 2 are referred to individually herein as a "Reporting Person" and collectively as the "Reporting Persons."

The address of the principal business office of GEO, NEA 18 VGE, each Control Entity and Sandell is New Enterprise Associates, 1954 Greenspring Drive, Suite 600, Timonium, Maryland 21093. The address of the principal business office of Behbahani, Chang, Makhzoumi, Walker and Yang is New Enterprise Associates, 2855 Sand Hill Road, Menlo Park, California 94025. The address of the principal business office of Florence and Mathers is New Enterprise Associates, 104 5th Avenue, 19th Floor, New York, New York 10011.

The principal business of GEO and NEA 18 VGE is to invest in and assist growth-oriented businesses located principally in the United States. The principal business of NEA Partners 18 VGE is to act as the sole general partner of NEA 18 VGE. The principal business of NEA 18 VGE LLC is to act as the sole general partner of NEA Partners 18 VGE. The principal business of each of the Managers is to manage the Control Entities, NEA 18 VGE, GEO and a number of affiliated partnerships with similar businesses.

During the five years prior to the date hereof, none of the Reporting Persons has been convicted in a criminal proceeding or has been a party to a civil proceeding ending in a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

GEO and NEA 18 VGE LLC are limited liability companies organized under the laws of the State of Delaware. NEA 18 VGE and NEA Partners 18 VGE are limited partnerships organized under the laws of the State of Delaware. Each of the Managers is a United States citizen.

As of February 23, 2026, GEO is the record owner of 1,000,000 shares of Common Stock and may be deemed to beneficially hold 3,065,134 shares of Common Stock underlying the GEO Warrants (collectively, the "GEO Shares"). As the sole member of GEO, NEA 18 VGE may be deemed to own beneficially the GEO Shares. As the general partner of NEA 18 VGE, NEA Partners 18 VGE may be deemed to own beneficially the GEO Shares. As the sole general partner of NEA Partners 18 VGE, NEA 18 VGE LLC may be deemed to own beneficially the GEO Shares. As members of NEA 18 VGE LLC, each of the Managers may be deemed to own beneficially the GEO Shares. Each Reporting Person disclaims beneficial ownership of the GEO Shares other than those shares which such person owns of record. The percentage of outstanding Common Stock of the Issuer which may be deemed to be beneficially owned by each Reporting Person is set forth on Line 13 of such Reporting Person's cover sheet. Such percentage was calculated based on 234,521,381 shares of Common Stock, which includes (i) the 231,456,247 shares of Common Stock reported by the Issuer to be outstanding as of October 31, 2025, on the Issuer's Form 10-Q filed with the SEC on November 5, 2025 and (ii) the GEO Warrants.

Regarding the number of shares as to which such person has: (i) sole power to vote or to direct the vote: See line 7 of cover sheets (ii) shared power to vote or to direct the vote: See line 8 of cover sheets (iii) sole power to dispose or to direct the disposition: See line 9 of cover sheets (iv) shared power to dispose or to direct the disposition: See line 10 of cover sheets.

Except as set forth in Item 3 above, none of the Reporting Persons has effected any transaction in the Issuer's Common Stock during the last 60 days.

No other person is known to have the right to receive or the power to direct the receipt of dividends from, or any proceeds from the sale of, Common Stock beneficially owned by any of the Reporting Persons.

February 23, 2026.