Atossa Therapeutics Enters Securities Purchase Agreement With Institutional Investors For 1,363,638 Shares

Atossa Therapeutics, Inc. (NASDAQ:ATOS) ("Atossa" or the "Company"), a clinical-stage biopharmaceutical company developing novel therapies in oncology and other areas of high unmet clinical need, today announced that it has entered into a securities purchase agreement with institutional investors for the purchase and sale of 1,363,638 shares (the "Shares") of its common stock, par value $0.18 per share ("Common Stock") (or common stock equivalents in lieu thereof), Series A warrants to purchase up to 1,363,638 shares of Common Stock and short-term Series B warrants to purchase up to 1,363,638 shares of Common Stock (such warrants, collectively, the "Series Warrants") and accompanying Series Warrants in a registered direct offering. The Series Warrants will be exercisable six months following the date of issuance. The Series A warrants will expire on the five one-half (5.5) year anniversary of the date of issuance. The short-term Series B warrants will expire on the two (2) year anniversary of the date of issuance. The closing of the offering is expected to occur on or about June 12, 2026, subject to the satisfaction of customary closing conditions.

The aggregate gross proceeds to the Company from the offering are expected to be approximately $4.5 million before deducting the placement agent's fees and other estimated offering expenses payable by the Company. The potential additional gross proceeds to the Company from the Series Warrants, if fully exercised on a cash basis, will be approximately $12 million. No assurance can be given that any of the Series Warrants will be exercised, or that the Company will receive cash proceeds from the exercise of the Series Warrants. The Company currently intends to use the net proceeds from the offering for clinical development of its product candidates, working capital and general corporate purposes.