Alto Neuroscience Announces $50 Million Private Placement Financing (Form 8-K)

Alto Neuroscience Announces $50 Million Private Placement Financing

- Financing led by Perceptive Advisors with participation from new and existing biotech focused investors -

- Alto expects to use the proceeds of this financing to accelerate development of ALTO-207 in Treatment Resistant Depression -

Mountain View, Calif., October 20, 2025 - Alto Neuroscience, Inc. ("Alto") (NYSE: ANRO), a clinical-stage biopharmaceutical company focused on the development of novel precision medicines for neuropsychiatric disorders, announced today that it has entered into a securities purchase agreement with institutional and accredited investors to sell securities in a private placement financing (the "PIPE") for gross proceeds of approximately $50 million, before deducting offering expenses. The financing was led by Perceptive Advisors, with participation by new and existing institutional investors, including Commodore Capital, Vestal Point Capital, Vivo Capital, and a large biotech dedicated investor.

Alto intends to use the proceeds from the PIPE to accelerate the development of ALTO-207, a fixed-dose combination of pramipexole (a dopamine D3-preferring D3/D2 agonist) and ondansetron, following a successful FDA meeting regarding the development path of the program, as well as for working capital and general corporate purposes. Alto expects to initiate a Phase 2b study of ALTO-207 in treatment resistant depression (TRD) by mid-2026, which has the potential to be a pivotal study. With the funding from the PIPE, the Company now also expects to initiate a Phase 3 study of ALTO-207 in TRD patients by early 2027.

"We appreciate the support of this esteemed group of investors, which reflects strong confidence in Alto's precision psychiatry platform and clinical pipeline," said Amit Etkin, M.D., Ph.D., founder and chief executive officer of Alto Neuroscience. "Following the successful outcome of our FDA meeting for ALTO-207, this financing positions us to advance the program more rapidly toward pivotal studies and patients in need."

In the PIPE, Alto is selling an aggregate of 3,832,263 shares of its common stock at a price of $5.914 per share and, in lieu of common stock to certain investors, pre-funded warrants to purchase up to an aggregate of 4,622,251 shares of common stock at a purchase price of $5.9139 per pre-funded warrant. Each pre-funded warrant has an exercise price of $0.0001 per share of common stock, will be immediately exercisable, subject to certain conditions set forth in each pre-funded warrant, and will not expire. The PIPE is expected to close on October 21, 2025, subject to customary closing conditions. The financing was priced at-the-market under NYSE rules. Cooley LLP served as counsel to Alto for this transaction.

The securities to be sold in the PIPE, including the shares of common stock underlying the pre-funded warrants, have not been registered under the Securities Act of 1933, as amended, or applicable state securities laws. Accordingly, these securities may not be offered or sold in the United States except pursuant to an effective registration statement or an applicable exemption from the registration requirements of the Securities Act. Alto has agreed to file a registration statement with the Securities and Exchange Commission (SEC) registering the resale of the shares of common stock and shares of common stock issuable upon the exercise of the pre-funded warrants issued in the PIPE.