ATOS · Atossa Therapeutics, Inc.

Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest on the first anniversary of May 12, 2026.

Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest on the first anniversary of May 12, 2026.

Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest on the first anniversary of May 12, 2026.

Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest on the first anniversary of May 12, 2026.

Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest on the first anniversary of May 12, 2026.

Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest on the first anniversary of May 12, 2026.

Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest in three equal annual installments on the first three anniversaries of March 26, 2026.

On February 2, 2026, the Issuer effected a one-for-fifteen reverse stock split of its Common Stock (the "Reverse Stock Split"). The number of securities reported on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Represents a grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest in three equal annual installments on the first three anniversaries of March 26, 2026.

The options shall vest on a quarterly basis over 24 months following January 20, 2026, subject to the Reporting Person's continued service to the Issuer through each applicable vesting date. The options were issued on January 20, 2026, with an exercise price of $0.603, representing the closing stock price on January 20, 2026.

Represents the acquisition of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest one year from the Transaction Date.

The original Form 4, filed on January 22, 2026, is being amended by this Form 4 amendment solely to correct an administrative error regarding the number of RSUs acquired.

The options shall vest with respect to 25% on October 14, 2026, with the remaining 75% to vest in equal quarterly installments over the follwing three years, subject to the Reporting Person's continued service to the Issuer through each applicable vesting date.

The price reported represents the weighted average purchase price per share. The shares were purchased in multiple transactions at prices ranging from $0.8794 to $0.9100. Upon request by the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of share purchased at each separate price.

The options shall vest on a quarterly basis over 12 months following May 15, 2025, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued on May 15, 2025 with an exercise price of $0.99, representing the closing stock price on May 15, 2025.

The options shall vest on a quarterly basis over 12 months following May 15, 2025, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued on May 15, 2025 with an exercise price of $0.99, representing the closing stock price on May 15, 2025.

The options shall vest on a quarterly basis over 12 months following May 15, 2025, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued on May 15, 2025 with an exercise price of $0.99, representing the closing stock price on May 15, 2025.

The options shall vest on a quarterly basis over 12 months following May 15, 2025, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued on May 15, 2025 with an exercise price of $0.99, representing the closing stock price on May 15, 2025.

The options shall vest on a quarterly basis over 12 months following May 15, 2025, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued on May 15, 2025 with an exercise price of $0.99, representing the closing stock price on May 15, 2025.

The options shall vest on a quarterly basis over 12 months following May 15, 2025, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued on May 15, 2025 with an exercise price of $0.99, representing the closing stock price on May 15, 2025.

The options shall vest on a quarterly basis over 24 months following May 15, 2025, subject to the Reporting Person's continued service to the Issuer through each applicable vesting date. The options were issued on May 15, 2025, with an exercise price of $0.99, representing the closing stock price on May 15, 2025.

The options shall vest on a quarterly basis over 24 months following May 15, 2025, subject to the Reporting Person's continued service to the Issuer through each applicable vesting date. The options were issued on May 15, 2025, with an exercise price of $0.99, representing the closing stock price on May 15, 2025.

Reflects a reverse stock split of the Issuer's common stock at a ratio of 12:1 effective April 2018. The Reporting Person disclaims beneficial ownership of 11 shares of common stock owned by his spouse except to the extent of his pecuniary interest in the shares.

The options shall vest on a quarterly basis over 12 months following June 27, 2024, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued at approximately 9:30 a.m. (ET) on June 27, 2024 with an exercise price of $1.05, representing the most recently reported closing stock price on June 26, 2024.

The options shall vest on a quarterly basis over 12 months following June 27, 2024, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued at approximately 9:30 a.m. (ET) on June 27, 2024 with an exercise price of $1.05, representing the most recently reported closing stock price on June 26, 2024.

The options shall vest on a quarterly basis over 12 months following June 27, 2024, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued at approximately 9:30 a.m. (ET) on June 27, 2024 with an exercise price of $1.05, representing the most recently reported closing stock price on June 26, 2024.

The options shall vest on a quarterly basis over 12 months following June 27, 2024, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued at approximately 9:30 a.m. (ET) on June 27, 2024 with an exercise price of $1.05, representing the most recently reported closing stock price on June 26, 2024.

The options shall vest on a quarterly basis over 24 months following June 27, 2024, subject to the Reporting Person's continued service to the Issuer through each applicable vesting date. The options were issued at approximately 9:30 a.m. (ET) on June 27, 2024, with an exercise price of $1.05, representing the most recently reported closing stock price on June 26, 2024.

The options shall vest on a quarterly basis over 12 months following June 27, 2024, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued at approximately 9:30 a.m. (ET) on June 27, 2024 with an exercise price of $1.05, representing the most recently reported closing stock price on June 26, 2024.

The options shall vest on a quarterly basis over 12 months following June 27, 2024, subject to the Reporting Person's continued service through each applicable vesting date. The options were issued at approximately 9:30 a.m. (ET) on June 27, 2024 with an exercise price of $1.05, representing the most recently reported closing stock price on June 26, 2024.

The options shall vest on a quarterly basis over 24 months following June 27, 2024, subject to the Reporting Person's continued service to the Issuer through each applicable vesting date. The options were issued at approximately 9:30 a.m. (ET) on June 27, 2024, with an exercise price of $1.05, representing the most recently reported closing stock price on June 26, 2024.

The price reported represents the weighted average purchase price per share. The shares were purchased in multiple transactions at prices ranging from $1.74 to $1.78. Upon request from the staff of the U.S. Securities and Exchange Commission, the Issuer or a security holder of the Issuer, The Reporting Person will provide full information regarding the number of shares purchased at each separate price.

The options shall vest in four equal quarterly installments following March 9, 2024, subject to the Reporting Person's continued service through each applicable date.

The options shall vest in four equal quarterly installments following November 15, 2023.

The options shall vest in four equal quarterly installments following November 15, 2023.

The price reported represents the weighted average purchase price per share. The shares were purchased in multiple transactions at prices ranging from $0.93 to $0.99. Upon request from the staff of the U.S. Securities and Exchange Commission, the Issuer or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of shares purchased at each separate price.

Includes shares of common stock purchased on November 21, 2013, which were previously reported on a Form 4 filed by the Reporting Person on November 22, 2013 but erroneously omitted in subsequent filings.

The options shall vest with respect to 25% on the one year anniversary of June 1, 2023, and the remainder shall vest in equal quarterly installments over the following three years, subject to the reporting person's continued service through each applicable vesting date.

The options shall vest on a quarterly basis over the next 12 months. The options were issued at approximately 9:50 a.m. (ET) on May 4, 2023, with an exercise price of $0.662, representing the most recently reported closing stock price on May 3, 2023.

The options shall vest on a quarterly basis over the next 12 months. The options were issued at approximately 9:50 a.m. (ET) on May 4, 2023, with an exercise price of $0.662, representing the most recently reported closing stock price on May 3, 2023.

The options shall vest on a quarterly basis over the next 12 months. The options were issued at approximately 9:50 a.m. (ET) on May 4, 2023, with an exercise price of $0.662, representing the most recently reported closing stock price on May 3, 2023.

The options shall vest on a quarterly basis over the next 12 months. The options were issued at approximately 9:50 a.m. (ET) on May 4, 2023, with an exercise price of $0.662, representing the most recently reported closing stock price on May 3, 2023.

The options shall vest on a quarterly basis over the next 12 months. The options were issued at approximately 9:50 a.m. (ET) on May 4, 2023, with an exercise price of $0.662, representing the most recently reported closing stock price on May 3, 2023.

The option will vest and become exercisable on a quarterly basis over 24 months from the grant-date.

The option will vest and become exercisable on a quarterly basis over 24 months from the grant-date.

The options shall vest on a quarterly basis over the next 12 months. Option grant was issued at 9:30 a.m. (ET) on May 13, 2022, with an exercise price of $0.93, representing the most recently reported closing stock price on May 12, 2022.

The options shall vest on a quarterly basis over the next 12 months. Option grant was issued at 9:30 a.m. (ET) on May 13, 2022, with an exercise price of $0.93, representing the most recently reported closing stock price on May 12, 2022.

The options shall vest on a quarterly basis over the next 12 months. Option grant was issued at 9:30 a.m. (ET) on May 13, 2022, with an exercise price of $0.93, representing the most recently reported closing stock price on May 12, 2022.

The options shall vest on a quarterly basis over the next 12 months. Option grant was issued at 9:30 a.m. (ET) on May 13, 2022, with an exercise price of $0.93, representing the most recently reported closing stock price on May 12, 2022.