ALT

SEC source: 0001104659-23-009975 · tm235311-4_4seq1.xml · nonDerivative · entry 3

Roberts M Scot · CIK 0001705905 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 14,456

F4 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of RSUs.

SEC source: 0001104659-23-009975 · tm235311-4_4seq1.xml · nonDerivative · entry 2

Roberts M Scot · CIK 0001705905 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 16,639

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

SEC source: 0001104659-23-009974 · tm235311-3_4seq1.xml · derivative · entry 4

Harris Matthew Scott · CIK 0001787762 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,332

Underlying: Common Stock, par value $0.0001 · 6,166 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

F5 · derivative.exercise_date: The RSUs become vested in substantially equal annual installments over the 4 years following February 1, 2021, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

F5 · derivative.expiration_date: The RSUs become vested in substantially equal annual installments over the 4 years following February 1, 2021, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

SEC source: 0001104659-23-009974 · tm235311-3_4seq1.xml · nonDerivative · entry 3

Harris Matthew Scott · CIK 0001787762 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,900

F4 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of RSUs.

SEC source: 0001104659-23-009974 · tm235311-3_4seq1.xml · nonDerivative · entry 2

Harris Matthew Scott · CIK 0001787762 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 20,083

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

SEC source: 0001104659-23-009973 · tm235311-2_4seq1.xml · derivative · entry 4

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 33,090

Underlying: Common Stock, par value $0.0001 · 16,546 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

F5 · derivative.exercise_date: The RSUs become vested in substantially equal annual installments over the 4 years following February 1, 2021, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

F5 · derivative.expiration_date: The RSUs become vested in substantially equal annual installments over the 4 years following February 1, 2021, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

SEC source: 0001104659-23-009973 · tm235311-2_4seq1.xml · nonDerivative · entry 3

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 238,601

F4 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of RSUs.

SEC source: 0001104659-23-009973 · tm235311-2_4seq1.xml · nonDerivative · entry 2

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 246,259

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

SEC source: 0001104659-23-009975 · tm235311-4_4seq1.xml · nonDerivative · entry 1

Roberts M Scot · CIK 0001705905 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 10,473

F1 · kind: These shares were purchased due to participation by the reporting individual in the Issuer's 2019 Employee Stock Purchase Plan ("ESPP"). It pertains to the ESPP purchase period from August 1, 2022 through January 31, 2023.

F2 · price: In accordance with the ESPP, these shares were purchased based on 85% of the opening price of the issuer's common stock on August 1, 2022.

SEC source: 0001104659-23-009974 · tm235311-3_4seq1.xml · nonDerivative · entry 1

Harris Matthew Scott · CIK 0001787762 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 13,917

F1 · kind: These shares were purchased due to participation by the reporting individual in the Issuer's 2019 Employee Stock Purchase Plan ("ESPP"). It pertains to the ESPP purchase period from August 1, 2022 through January 31, 2023.

F2 · price: In accordance with the ESPP, these shares were purchased based on 85% of the opening price of the issuer's common stock on August 1, 2022.

SEC source: 0001104659-23-009973 · tm235311-2_4seq1.xml · nonDerivative · entry 1

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 229,713

F1 · kind: These shares were purchased due to participation by the reporting individual in the Issuer's 2019 Employee Stock Purchase Plan ("ESPP"). It pertains to the ESPP purchase period from August 1, 2022 through January 31, 2023.

F2 · price: In accordance with the ESPP, these shares were purchased based on 85% of the opening price of the issuer's common stock on August 1, 2022.

SEC source: 0001104659-23-009972 · tm235311-1_4seq1.xml · nonDerivative · entry 1

Eisenstadt Richard I · CIK 0001515806 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,010

F1 · kind: These shares were purchased due to participation by the reporting individual in the Issuer's 2019 Employee Stock Purchase Plan ("ESPP"). It pertains to the ESPP purchase period from August 1, 2022 through January 31, 2023.

F2 · price: In accordance with the ESPP, these shares were purchased based on 85% of the opening price of the issuer's common stock on August 1, 2022.

SEC source: 0001104659-23-009355 · tm235142-4_4seq1.xml · derivative · entry 2

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 107,100

Underlying: Common Stock, par value $0.0001 · 107,100 shares

Expires not disclosed

F2 · derivative.exercise_price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

F3 · derivative.exercise_date: The RSUs become vested in substantially equal annual installments over the 4 years following January 30, 2023, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

F3 · derivative.expiration_date: The RSUs become vested in substantially equal annual installments over the 4 years following January 30, 2023, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

SEC source: 0001104659-23-009355 · tm235142-4_4seq1.xml · derivative · entry 1

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 302,900

Underlying: Common Stock, par value $0.0001 · 302,900 shares

Expires 2033-01-30

F1 · derivative.exercise_date: Twenty-five percent of the shares underlying the option become vested and exercisable on January 30, 2024 and the remaining 75% of the shares underlying the option become vested and exercisable in substantially equal monthly installments over the 36 months following January 30, 2024, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-23-009354 · tm235142-3_4seq1.xml · derivative · entry 2

Roberts M Scot · CIK 0001705905 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 37,100

Underlying: Common Stock, par value $0.0001 · 37,100 shares

Expires not disclosed

F2 · derivative.exercise_price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

F3 · derivative.exercise_date: The RSUs become vested in substantially equal annual installments over the 4 years following January 30, 2023, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

F3 · derivative.expiration_date: The RSUs become vested in substantially equal annual installments over the 4 years following January 30, 2023, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

SEC source: 0001104659-23-009354 · tm235142-3_4seq1.xml · derivative · entry 1

Roberts M Scot · CIK 0001705905 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 105,000

Underlying: Common Stock, par value $0.0001 · 105,000 shares

Expires 2033-01-30

F1 · derivative.exercise_date: Twenty-five percent of the shares underlying the option become vested and exercisable on January 30, 2024 and the remaining 75% of the shares underlying the option become vested and exercisable in substantially equal monthly installments over the 36 months following January 30, 2024, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-23-009353 · tm235142-2_4seq1.xml · derivative · entry 2

Eisenstadt Richard I · CIK 0001515806 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 37,100

Underlying: Common Stock, par value $0.0001 · 37,100 shares

Expires not disclosed

F2 · derivative.exercise_price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

F3 · derivative.exercise_date: The RSUs become vested in substantially equal annual installments over the 4 years following January 30, 2023, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

F3 · derivative.expiration_date: The RSUs become vested in substantially equal annual installments over the 4 years following January 30, 2023, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

SEC source: 0001104659-23-009353 · tm235142-2_4seq1.xml · derivative · entry 1

Eisenstadt Richard I · CIK 0001515806 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 105,000

Underlying: Common Stock, par value $0.0001 · 105,000 shares

Expires 2033-01-30

F1 · derivative.exercise_date: Twenty-five percent of the shares underlying the option become vested and exercisable on January 30, 2024 and the remaining 75% of the shares underlying the option become vested and exercisable in substantially equal monthly installments over the 36 months following January 30, 2024, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-23-009352 · tm235142-1_4seq1.xml · derivative · entry 2

Harris Matthew Scott · CIK 0001787762 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 37,100

Underlying: Common Stock, par value $0.0001 · 37,100 shares

Expires not disclosed

F2 · derivative.exercise_price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

F3 · derivative.exercise_date: The RSUs become vested in substantially equal annual installments over the 4 years following January 30, 2023, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

F3 · derivative.expiration_date: The RSUs become vested in substantially equal annual installments over the 4 years following January 30, 2023, subject to the reporting person's continued service through the applicable vesting date, and have no expiration date.

SEC source: 0001104659-23-009352 · tm235142-1_4seq1.xml · derivative · entry 1

Harris Matthew Scott · CIK 0001787762 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 105,000

Underlying: Common Stock, par value $0.0001 · 105,000 shares

Expires 2033-01-30

F1 · derivative.exercise_date: Twenty-five percent of the shares underlying the option become vested and exercisable on January 30, 2024 and the remaining 75% of the shares underlying the option become vested and exercisable in substantially equal monthly installments over the 36 months following January 30, 2024, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-23-000836 · tm231429-2_4seq1.xml · derivative · entry 2

Jordt Raymond M · CIK 0001960780 · Chief Business Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 37,500

Underlying: Common Stock, par value $0.0001 · 37,500 shares

Expires not disclosed

F2 · derivative.exercise_price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

F3 · derivative.exercise_date: The RSUs become vested and exercisable over four (4) years with 25% of the shares vesting on January 1, 2024, 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.

F3 · derivative.expiration_date: The RSUs become vested and exercisable over four (4) years with 25% of the shares vesting on January 1, 2024, 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.

SEC source: 0001104659-23-000836 · tm231429-2_4seq1.xml · derivative · entry 1

Jordt Raymond M · CIK 0001960780 · Chief Business Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 125,000

Underlying: Common Stock, par value $0.0001 · 125,000 shares

Expires 2033-01-03

F1 · derivative.exercise_date: The shares underlying the option become vested and exercisable over four (4) years with 25% of the shares vesting on January 1, 2024, with the remainder vesting in equal monthly installments for the following thirty-six (36) months, subject to the reporting person's continued service on each applicable vesting date.

SEC source: 0001104659-23-000469 · tm231429-3_4seq1.xml · derivative · entry 3

Eisenstadt Richard I · CIK 0001515806 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 37,500

Underlying: Common Stock, par value $0.0001 · 12,500 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

F3 · derivative.exercise_date: The RSUs become vested and exercisable over four (4) years with 25% of the shares vesting on December 31, 2022, 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.

F3 · derivative.expiration_date: The RSUs become vested and exercisable over four (4) years with 25% of the shares vesting on December 31, 2022, 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.

SEC source: 0001104659-23-000469 · tm231429-3_4seq1.xml · nonDerivative · entry 2

Eisenstadt Richard I · CIK 0001515806 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 10,838

F2 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of RSUs.

SEC source: 0001104659-23-000469 · tm231429-3_4seq1.xml · nonDerivative · entry 1

Eisenstadt Richard I · CIK 0001515806 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 13,866

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested.

SEC source: 0001104659-22-129514 · tm2233389-1_4seq1.xml · derivative · entry 3

Pisano Wayne · CIK 0001743611 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock, par value $0.0001 · 20,000 shares

Expires 2029-01-02

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: The option became vested and exercisable in two equal installments on February 28, 2019 and August 30, 2019, in each case, generally subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-129514 · tm2233389-1_4seq1.xml · nonDerivative · entry 2

Pisano Wayne · CIK 0001743611 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 8,498

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.0000 to $15.0900, inclusive. The reporting person undertakes to provide to Altimmune, Inc., any security holder of Altimmune, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.

SEC source: 0001104659-22-129514 · tm2233389-1_4seq1.xml · nonDerivative · entry 1

Pisano Wayne · CIK 0001743611 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 28,498

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001104659-22-123652 · tm2231773-1_4seq1.xml · nonDerivative · entry 1

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 227,775

F1 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of restricted stock.

SEC source: 0001104659-22-120752 · tm2231089-1_4seq1.xml · derivative · entry 3

Drutz David · CIK 0001428764 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock, par value $0.0001 · 139 shares

Expires 2022-12-31

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: This option was previously reported as covering 4,178 shares at an exercise price of $0.08 per share, but was adjusted to reflect a one-for-thirty reverse stock split that occurred on September 13, 2018.

F2 · shares: This option was previously reported as covering 4,178 shares at an exercise price of $0.08 per share, but was adjusted to reflect a one-for-thirty reverse stock split that occurred on September 13, 2018.

F3 · derivative.exercise_date: This option is fully vested and exercisable as of the date hereof.

F2 · derivative.underlying_shares: This option was previously reported as covering 4,178 shares at an exercise price of $0.08 per share, but was adjusted to reflect a one-for-thirty reverse stock split that occurred on September 13, 2018.

SEC source: 0001104659-22-120752 · tm2231089-1_4seq1.xml · nonDerivative · entry 1

Drutz David · CIK 0001428764 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 20,151

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001104659-22-112955 · tm2229283-1_4seq1.xml · nonDerivative · entry 1

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 230,782

F1 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of restricted stock.

SEC source: 0001104659-22-105233 · tm2227318-1_4seq1.xml · nonDerivative · entry 1

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 233,789

F1 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of restricted stock.

SEC source: 0001104659-22-104779 · tm2227177-5_4seq1.xml · derivative · entry 1

Pisano Wayne · CIK 0001743611 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,500

Underlying: Common Stock, par value $0.0001 · 23,500 shares

Expires 2032-09-29

F1 · derivative.exercise_date: The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following September 29, 2022, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-104780 · tm2227177-6_4seq1.xml · derivative · entry 1

Drutz David · CIK 0001428764 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,500

Underlying: Common Stock, par value $0.0001 · 23,500 shares

Expires 2032-09-29

F1 · derivative.exercise_date: The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following September 29, 2022, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-104778 · tm2227177-4_4seq1.xml · derivative · entry 1

GILL JOHN · CIK 0001409939 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,500

Underlying: Common Stock, par value $0.0001 · 23,500 shares

Expires 2032-09-29

F1 · derivative.exercise_date: The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following September 29, 2022, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-104781 · tm2227177-7_4seq1.xml · derivative · entry 1

Jorkasky Diane · CIK 0001527204 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,500

Underlying: Common Stock, par value $0.0001 · 23,500 shares

Expires 2032-09-29

F1 · derivative.exercise_date: The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following September 29, 2022, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-104776 · tm2227177-2_4seq1.xml · derivative · entry 1

SAYARE MITCHEL · CIK 0001201196 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,500

Underlying: Common Stock, par value $0.0001 · 23,500 shares

Expires 2032-09-29

F1 · derivative.exercise_date: The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following September 29, 2022, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-104777 · tm2227177-3_4seq1.xml · derivative · entry 1

Schafer Klaus · CIK 0001705904 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,500

Underlying: Common Stock, par value $0.0001 · 23,500 shares

Expires 2032-09-29

F1 · derivative.exercise_date: The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following September 29, 2022, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-104775 · tm2227177-1_4seq1.xml · derivative · entry 1

Hodges Philip · CIK 0001705562 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,500

Underlying: Common Stock, par value $0.0001 · 23,500 shares

Expires 2032-09-29

F1 · derivative.exercise_date: The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following September 29, 2022, subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-097013 · tm2224977-1_4seq1.xml · nonDerivative · entry 2

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 236,797

F2 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $20.00 to $20.19, inclusive. The reporting person undertakes to provide to Altimmune, Inc., any security holder of Altimmune, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.

SEC source: 0001104659-22-097013 · tm2224977-1_4seq1.xml · nonDerivative · entry 1

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 256,797

F1 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of restricted stock.

SEC source: 0001104659-22-090288 · tm2223405-1_4seq1.xml · nonDerivative · entry 1

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 259,804

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.00 to $15.25, inclusive. The reporting person undertakes to provide to Altimmune, Inc., any security holder of Altimmune, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.

SEC source: 0001104659-23-078839 · tm2320770-1_4seq1.xml · nonDerivative · entry 1

GILL JOHN · CIK 0001409939 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,771

F1 · shares: Pursuant to that certain Form 5 filed on February 14, 2022, the Reporting Person gifted these 2,714 shares of common stock on December 27, 2021 to an immediate family member.

SEC source: 0001104659-22-085624 · tm2222488-3_4seq1.xml · nonDerivative · entry 1

Harris Matthew Scott · CIK 0001787762 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,621

F1 · kind: These shares were purchased due to participation by the reporting individual in the Issuer's 2019 Employee Stock Purchase Plan ("ESPP"). It pertains to the ESPP purchase period from February 1, 2022 through July 31, 2022.

SEC source: 0001104659-22-085619 · tm2222488-2_4seq1.xml · nonDerivative · entry 1

Roberts M Scot · CIK 0001705905 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 9,037

F1 · kind: These shares were purchased due to participation by the reporting individual in the Issuer's 2019 Employee Stock Purchase Plan ("ESPP"). It pertains to the ESPP purchase period from February 1, 2022 through July 31, 2022.

SEC source: 0001104659-22-085617 · tm2222488-1_4seq1.xml · nonDerivative · entry 1

Eisenstadt Richard I · CIK 0001515806 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,366

F1 · kind: These shares were purchased due to participation by the reporting individual in the Issuer's 2019 Employee Stock Purchase Plan ("ESPP"). It pertains to the ESPP purchase period from February 1, 2022 through July 31, 2022.

SEC source: 0001104659-22-084791 · tm2222306-1_4seq1.xml · nonDerivative · entry 1

Garg Vipin K · CIK 0001515813 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 274,804

F1 · kind: Vesting transaction: Shares surrendered to the Issuer solely to cover taxes associated with vesting of restricted stock.

SEC source: 0001104659-22-077433 · tm2220386-1_4seq1.xml · derivative · entry 9

Roberts M Scot · CIK 0001705905 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 14,250

Underlying: Common Stock, par value $0.0001 · 787 shares

Expires 2029-03-26

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: Twenty-five percent of the shares underlying the option become vested and exercisable on the first anniversary of the Grant Date and the remaining 75% of the shares underlying the option become vested and exercisable in substantially equal monthly installments over the 36 months following the one-year anniversary of the Grant Date, in each case, generally subject to the reporting person's continued service through the applicable vesting date.

SEC source: 0001104659-22-077433 · tm2220386-1_4seq1.xml · nonDerivative · entry 5

Roberts M Scot · CIK 0001705905 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 8,305

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.