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Form SCHEDULE 13G Altimmune, Inc. Filed by: TCG Crossover GP II, LLC

May 1, 2026 4:37 PM





Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
Rule 13d-1(b)
Rule 13d-1(c)
Rule 13d-1(d)




schemaVersion:


SCHEDULE 13G




Comment for Type of Reporting Person: Consists of (i) 5,000,000 shares of Common Stock and (ii) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants (the Common Warrants) held of record by TCG Crossover II (as defined in Item 2(a) below). TCG Crossover GP II (as defined in Item 2(a) below) is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. The Common Warrants contain a provision which prohibits the exercise of the Common Warrants to the extent that doing so would result in the holder of the Common Warrants (together with the holder's affiliates and any other persons acting as a group together with the holder or any of the holder's affiliates) beneficially owning more than 9.99 percent of the shares of Common Stock then outstanding immediately after giving effect to such exercise (the Beneficial Ownership Limitation). As of the date of this filing, the Reporting Persons (as defined in Item 2(a) below) hold less than the Beneficial Ownership Limitation in the aggregate. Based on 199,199,358 shares of Common Stock, as follows: (a) 194,199,358 outstanding as of April 24, 2026, following the underwritten offering that closed on April 24, 2026 (the Offering), as reported by the Issuer (as defined in Item 1(a) below) in its prospectus filed with the United States Securities and Exchange Commission (the Commission) on April 24, 2026 (the Prospectus), plus (b) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover II.


SCHEDULE 13G




Comment for Type of Reporting Person: Consists of (i) 5,000,000 shares of Common Stock and (ii) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover II. TCG Crossover GP II is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. The Common Warrants contain a provision which prohibits the exercise of the Common Warrants due to the Beneficial Ownership Limitation. As of the date of this filing, the Reporting Persons hold less than the Beneficial Ownership Limitation in the aggregate. Based on 199,199,358 shares of Common Stock, as follows: (a) 194,199,358 outstanding as of April 24, 2026, following the Offering, as reported by the Issuer in the Prospectus, plus (b) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover II.


SCHEDULE 13G




Comment for Type of Reporting Person: Consists of (i) 5,000,000 shares of Common Stock and (ii) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover III (as defined in Item 2(a) below). TCG Crossover GP III (as defined in Item 2(a) below) is the general partner of TCG Crossover III and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP III and may be deemed to share voting, investment and dispositive power with respect to these securities. The Common Warrants contain a provision which prohibits the exercise of the Common Warrants due to the Beneficial Ownership Limitation. As of the date of this filing, the Reporting Persons hold less than the Beneficial Ownership Limitation in the aggregate. Based on 199,199,358 shares of Common Stock, as follows: (a) 194,199,358 outstanding as of April 24, 2026, following the Offering, as reported by the Issuer in the Prospectus, plus (b) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover III.


SCHEDULE 13G




Comment for Type of Reporting Person: Consists of (i) 5,000,000 shares of Common Stock and (ii) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover III. TCG Crossover GP III is the general partner of TCG Crossover III and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP III and may be deemed to share voting, investment and dispositive power with respect to these securities. The Common Warrants contain a provision which prohibits the exercise of the Common Warrants due to the Beneficial Ownership Limitation. As of the date of this filing, the Reporting Persons hold less than the Beneficial Ownership Limitation in the aggregate. Based on 199,199,358 shares of Common Stock, as follows: (a) 194,199,358 outstanding as of April 24, 2026, following the Offering, as reported by the Issuer in the Prospectus, plus (b) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover III.


SCHEDULE 13G




Comment for Type of Reporting Person: Consists of (i) 5,000,000 shares of Common Stock held of record by TCG Crossover II, (ii) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover II, (iii) 5,000,000 shares of Common Stock held of record by TCG Crossover III, and (iv) 5,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover III. TCG Crossover GP II is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to the securities held of record by TCG Crossover II. TCG Crossover GP III is the general partner of TCG Crossover III and may be deemed to have voting, investment, and dispositive power with respect to the securities held of record by TCG Crossover III. Chen Yu is the sole managing member of each of TCG Crossover GP II and TCG Crossover GP III and may be deemed to share voting, investment and dispositive power with respect to the securities held of record by TCG Crossover II and TCG Crossover III. The Common Warrants contain a provision which prohibits the exercise of the Common Warrants due to the Beneficial Ownership Limitation. As of the date of this filing, the Reporting Persons hold less than the Beneficial Ownership Limitation in the aggregate. Based on 204,199,358 shares of Common Stock, as follows: (a) 194,199,358 outstanding as of April 24, 2026, following the Offering, as reported by the Issuer in the Prospectus, plus (b) an aggregate of 10,000,000 shares of Common Stock issuable upon exercise of Common Warrants held of record by TCG Crossover II and TCG Crossover III.


SCHEDULE 13G



TCG Crossover GP II, LLC
Signature:/s/ Craig Skaling
Name/Title:Craig Skaling, Authorized Signatory
Date:05/01/2026
TCG Crossover Fund II, L.P.
Signature:/s/ Craig Skaling
Name/Title:Craig Skaling, Authorized Signatory
Date:05/01/2026
TCG Crossover GP III, LLC
Signature:/s/ Craig Skaling
Name/Title:Craig Skaling, Authorized Signatory
Date:05/01/2026
TCG Crossover Fund III, L.P.
Signature:/s/ Craig Skaling
Name/Title:Craig Skaling, Authorized Signatory
Date:05/01/2026
Chen Yu
Signature:/s/ Craig Skaling
Name/Title:Craig Skaling, as Attorney-in-Fact for Chen Yu
Date:05/01/2026
Exhibit Information

Exhibit 1 - Joint Filing Agreement

ATTACHMENTS / EXHIBITS

EX-99.1

Categories

SEC Filings