[Form 4] Altimmune, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Catherine A. Sohn, a director of Altimmune, Inc. (ALT), was granted stock options covering 48,800 shares with an exercise price of $3.92. The options become vested and exercisable in substantially equal monthly installments over the 12 months following the 09/25/2025 grant date, and they expire on 09/25/2035. After the grant the reporting person beneficially owns 48,800 option shares on a direct basis. The grant is an equity-based director compensation intended to align interests with shareholders; if exercised it will convert into common stock.

Positive

• Equity alignment: Director granted 48,800 stock options to align interests with shareholders
• Clear vesting: Options vest in substantially equal monthly installments over 12 months, providing retention incentive

Negative

• Potential dilution: Exercise of 48,800 options would increase the outstanding common shares
• Concentration: The entire reported beneficial ownership is in options, not exercised common stock

Insights

Corporate Governance Expert

TL;DR: Routine director equity grant to align interests; vesting schedule is front-loaded over one year.

This Form 4 discloses a standard equity award to a company director rather than an executive officer. The option count (48,800) and a 10-year term are typical for long-term alignment. The 12-month monthly vesting schedule indicates relatively rapid realization of rights contingent on continued service. From a governance perspective, such awards are common practice to retain and incentivize board members without immediate cash outlay.

Equity Compensation Analyst

TL;DR: Structured option grant with clear vesting and exercise terms; impact depends on eventual exercise and share dilution.

The instrument is a non-derivative option exercisable into common stock, exercisable through 09/25/2035 at an exercise price of $3.92. The reporting shows direct beneficial ownership of 48,800 underlying shares post-grant. Key operational implications are straightforward: these options will only dilute outstanding common stock if exercised, and their economic value to the director depends on future share price performance relative to the $3.92 strike.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person^*

Sohn Catherine A.

(Last) (First) (Middle)

C/O ALTIMMUNE, INC., 910 CLOPPER ROAD,

SUITE 201S

(Street)

GAITHERSBURG MD 20878

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Altimmune, Inc. [ ALT ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
09/25/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Options (option to buy)	$3.92	09/25/2025		A		48,800		(1)	09/25/2035	Common Stock, par value $0.0001	48,800	$0.00	48,800	D

Explanation of Responses:

1. The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following September 25, 2025, subject to the reporting person's continued service through the applicable vesting date.

	/s/ Gregory Weaver, as Attorney-in-Fact	09/29/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did Altimmune insider Catherine A. Sohn acquire on 09/25/2025?

The reporting person was granted 48,800 stock options with an exercise price of $3.92 and an expiration date of 09/25/2035.

How do the options vest for Catherine A. Sohn (ALT)?

The options vest and become exercisable in substantially equal monthly installments over the 12 months following the 09/25/2025 grant, subject to continued service.

How many shares does the Form 4 report Catherine A. Sohn beneficially owns after the transaction?

The Form 4 reports beneficial ownership of 48,800 underlying shares on a direct basis following the reported transaction.

What is the exercise price and term of the options reported for ALT?

The options have an exercise price of $3.92 and an expiration (term) of 10 years, expiring on 09/25/2035.

Are these options direct or indirect ownership in the Form 4?

The Form 4 indicates direct ownership (listed as 'D') of the 48,800 options.