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Altimmune CCO vests 24,000 RSUs, withholds shares

Altimmune’s Chief Commercial Officer saw RSUs vest into common stock, with a portion of shares withheld to satisfy taxes.

(Neutral)
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Altimmune, Inc. (ALT) reported that Chief Commercial Officer Linda M. Richardson had 24,000 Restricted Stock Units convert into 24,000 shares of common stock on September 16, 2026. Of these, 6,826 shares were surrendered to Altimmune solely to cover taxes on the RSU vesting. After this transaction, 72,000 RSUs remain outstanding, vesting over four years with 25% on September 16, 2026 and the balance in equal annual installments over the next three years, subject to continued service.

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Insider Richardson Linda M
Role Chief Commercial Officer
Type Security Shares Price Value
Exercise Restricted Stock Units F1, F3 24,000 $0.00 $0.00
Exercise Common Stock, par value $0.0001 F1 24,000 $0.00 $0.00
Tax Withholding Common Stock, par value $0.0001 F2 6,826 $3.24 $22K
Holdings After Transaction: Restricted Stock Units — 72,000 contracts (Direct); Common Stock, par value $0.0001 — 17,174 shares (Direct)
Footnotes (3)
  1. F1. Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.
  2. F2. Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of RSUs.
  3. F3. The RSUs become vested over four (4) years with 25% of the shares vesting on September 16, 2026, with the remainder vesting in equal annual installments for the following three (3) years, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.
RSUs converted 24,000 units Restricted Stock Units converted into common stock on September 16, 2026
Common shares acquired from RSUs 24,000 shares Common stock received upon RSU conversion on September 16, 2026
Shares withheld for taxes 6,826 shares Shares surrendered to Altimmune solely to cover taxes on RSU vesting
Tax withholding price per share $3.24 per share Price used for shares surrendered to cover taxes on September 16, 2026
RSUs remaining after transaction 72,000 units Restricted Stock Units held after the September 16, 2026 conversion
Initial vesting percentage 25% Portion of RSUs vesting on September 16, 2026
Remaining vesting period 3 years RSUs vest in equal annual installments over the next three years
Restricted Stock Units financial
"Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share"
Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.
vesting financial
"Vesting transaction: Shares surrendered to the Issuer solely to cover taxes"
Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.
par value financial
"Common Stock, par value $0.0001"
Par value is the fixed amount printed on a bond or stock that represents its original value when issued. It’s like the face value of a coin or bill—what the issuer promises to pay back or the starting price of a stock—though it often doesn’t change with market prices. It matters because it helps determine certain financial details, like how much the company will pay back at maturity.
taxes associated with vesting financial
"cover taxes associated with vesting of RSUs"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did ALT report for Chief Commercial Officer Linda Richardson?

Altimmune reported that 24,000 RSUs held by Chief Commercial Officer Linda M. Richardson converted into 24,000 shares of common stock on September 16, 2026, as part of her equity compensation vesting schedule.

How many Altimmune (ALT) shares were withheld for taxes in this Form 4?

Altimmune disclosed that 6,826 shares of common stock were surrendered to the issuer at $3.24 per share solely to cover taxes associated with the vesting of RSUs on September 16, 2026.

How many Altimmune (ALT) RSUs does Linda Richardson still hold after this transaction?

Following the September 16, 2026 conversion, Linda M. Richardson beneficially holds 72,000 Restricted Stock Units (RSUs), each representing a contingent right to receive one share of Altimmune common stock when vested.

What is the vesting schedule for Linda Richardson’s RSUs at Altimmune (ALT)?

The RSUs vest over four years: 25% of the shares vest on September 16, 2026, with the remaining 75% vesting in equal annual installments over the following three years, subject to her continued service.

Were Linda Richardson’s Altimmune (ALT) transactions under a Rule 10b5-1 trading plan?

No. The filing indicates no Rule 10b5-1 trading plan for these transactions; they are reported as equity compensation vesting and related share withholding for tax purposes.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Learn about SEC filing dates
SEC Form 4
FORM 4UNITED 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
OMB APPROVAL
OMB Number:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
Richardson Linda M

(Last)(First)(Middle)
910 CLOPPER ROAD
SUITE 201S

(Street)
GAITHERSBURG MARYLAND 20878

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
Altimmune, Inc. [ ALT ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director10% Owner
XOfficer (give title below)Other (specify below)
Chief Commercial Officer
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
09/16/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

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)
CodeVAmount(A) or (D)Price
Common Stock, par value $0.000109/16/2026M24,000A$0(1)24,000D
Common Stock, par value $0.000109/16/2026F(2)6,826D$3.2417,174D
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Restricted Stock Units(1)09/16/2026M24,000 (3) (3)Common Stock, par value $0.000124,000$072,000D
Explanation of Responses:
1. Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.
2. Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of RSUs.
3. The RSUs become vested over four (4) years with 25% of the shares vesting on September 16, 2026, with the remainder vesting in equal annual installments for the following three (3) years, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.
/s/ Gregory Weaver, as Attorney-in-Fact09/17/2026
** Signature of Reporting PersonDate
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.
* Form 4: SEC 1474 (03-26)

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