ATOSSA THERAPEUTICS, INC.

As of the Effective Date (as defined below):

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each 5 to 20 shares of common stock outstanding (depending on the Reverse Stock Split ratio selected by the Board) will be combined, automatically and without any action on the part of the Company or its stockholders, into one new share of common stock;

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no fractional shares of common stock will be issued; instead, stockholders who would otherwise receive a fractional share will receive cash in lieu of the fractional share (as detailed below);

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proportionate adjustments will be made to the number of shares issuable upon the exercise of all then-outstanding stock options, which will result in a proportional decrease in the number of shares of common stock reserved for issuance upon exercise of such stock options and a proportional increase in the exercise price of all such stock options;

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the number of shares of common stock then reserved for issuance under our equity compensation plans will be reduced proportionately; and

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the number of shares of common stock then reserved for issuance pursuant to the Company’s Series B Convertible Preferred Stock will be reduced proportionately and the conversion price will be increased proportionately.

The following table summarizes, for illustrative purposes only, the anticipated effects of a Reverse Stock Split on our shares available for issuance based on information as of November 1, 2025 and without giving effect to the treatment of fractional shares:

A Reverse Stock Split would affect all stockholders uniformly. As of the Effective Date, each stockholder would own a reduced number of shares of common stock. Percentage ownership interests, voting rights and other rights and preferences would not be affected, except to the extent that the Reverse Stock Split would result in fractional shares (as described below).

A Reverse Stock Split would not affect the registration of our common stock under Section 12(b) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and we would continue to be subject to the periodic reporting and other requirements of the Exchange Act. Barring delisting by Nasdaq, our common stock would continue to be listed on Nasdaq under the symbol “ATOS,” but would have a new Committee on Uniform Securities Identification Procedures (CUSIP) number after the Effective Date.