Material Event (Form 8-K)

On August 12, 2026, Outlook Therapeutics, Inc. (the "Company") entered into an underwriting agreement (the "Underwriting Agreement") with Piper Sandler & Co. and BTIG, LLC, as representatives of the several underwriters named therein (collectively, the "Underwriters"), relating to the public offering (the "Offering") by the Company of (i) 55,555,556 shares of the Company's common stock, par value $0.01 per share (the "Common Stock"), and (ii) accompanying warrants to purchase up to an aggregate of 55,555,556 shares of Common Stock (the "Warrants") at a combined public offering price of $0.99 per share of Common Stock and accompanying Warrant. The shares of Common Stock and Warrants are immediately separable and will be issued separately.

The Offering is scheduled to close on or about August 14, 2026, subject to customary closing conditions.

The Company also granted the Underwriters an option for a period of 30 days to purchase up to 8,333,333 additional shares of Common Stock and/or Warrants to purchase up to 8,333,333 additional shares of Common Stock at the public offering price, less the underwriting discounts and commissions. On August 12, 2026, the Underwriters exercised such option with respect to the Warrants to purchase up to 8,333,333 additional shares of Common Stock.

The Company estimates that the gross proceeds from the Offering will be approximately $55.0 million, before deducting the underwriting discounts and commissions and estimated offering expenses payable by the Company and excluding any exercise of the underwriter's option to purchase additional securities and assuming no exercise of the accompanying Warrants.

Each Warrant will have an initial exercise price per share of $1.10, subject to certain customary adjustments for recapitalizations, stock splits and similar actions. The Warrants will be exercisable immediately and will expire five years from the date of issuance. A holder (together with its affiliates and other attribution parties) may not exercise any portion of a Warrant to the extent that, immediately after giving effect to such exercise, the holder would own more than 4.99%, 9.99% or 19.99%, as applicable, of the Company's outstanding Common Stock immediately after exercise, which percentage may be changed at the holder's election to a lower or higher percentage not in excess of 19.99% (if exceeding such percentage would result in a change of control under Nasdaq Listing Rule 5635(b) or any successor rule) upon 61 days' notice to the Company subject to the terms of the Warrants.

The Offering is being made pursuant to the Company's effective registration statement on Form S-3 (Registration Statement No. 333-278340) previously filed with the Securities and Exchange Commission (the "SEC") and a prospectus supplement thereunder.

The Underwriting Agreement contains customary representations, warranties and agreements by the Company, customary conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities arising under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions. The representations, warranties and covenants contained in the Underwriting Agreement were made only for the purposes of the Underwriting Agreement and as of specific dates, and were solely for the benefit of the parties to the Underwriting Agreement.

GMS Ventures and Investments, the Company's largest stockholder, purchased an aggregate of 2,525,252 shares of Common Stock and accompanying Warrants in the Offering. Robert Jahr, the Company's Chief Executive Officer, and Lawrence Kenyon, the Company's Chief Financial Officer, purchased an aggregate of 151,515 and 101,010 shares of Common Stock and accompanying Warrants in the Offering, respectively.

The foregoing descriptions of the terms of the Underwriting Agreement and Warrants are each qualified in their entirety by reference to the Underwriting Agreement and form of Warrant, respectively, which are attached as Exhibit 1.1 and Exhibit 4.1 hereto, respectively, and incorporated by reference herein.

A copy of the legal opinion of Cooley LLP relating to the validity of the issuance and sale of the securities in the Offering is attached as Exhibit 5.1 hereto.