Atossa Therapeutics Inc. (NASDAQ: ATOS) entered into a securities purchase agreement with institutional investors for a registered direct offering expected to generate $4.5 million in gross proceeds before fees and expenses.

The Seattle-based biopharmaceutical company will sell 1,363,638 shares of common stock at $0.18 per share, along with Series A and Series B warrants to purchase additional shares. The Series A warrants expire 5.5 years from issuance, while Series B warrants expire after two years. Both warrant series become exercisable six months following issuance.

If all warrants are exercised for cash, the company could receive an additional $12 million in gross proceeds, bringing total potential proceeds to $16.5 million. The company stated no assurance can be given that warrants will be exercised.

Rodman & Renshaw LLC serves as the exclusive placement agent for the offering. The transaction is expected to close on June 12, 2026, subject to customary closing conditions.

Atossa plans to use net proceeds for clinical development of product candidates, working capital and general corporate purposes. The company develops therapies in oncology and other areas of unmet medical need, with lead product candidate (Z)-endoxifen currently in development across several clinical settings.

The securities are being offered through a shelf registration statement on Form S-3 filed with the Securities and Exchange Commission on May 13, 2024, and declared effective on May 23, 2024.