RA Capital Management Establishes 6.5% Stake in Altimmune, Inc. via Public Offering

On May 1, 2026, RA Capital Management, L.P., alongside Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P., filed a Schedule 13G indicating a new significant stake in Altimmune, Inc. (ALT). The reporting persons disclosed beneficial ownership of 13,000,000 shares of common stock, representing 6.5% of the company. This position consists of 6,500,000 shares of common stock and common stock warrants immediately exercisable for an additional 6,500,000 shares. The acquisition was triggered by an event on April 24, 2026, coinciding with the issuer's public offering of 64,250,000 shares. RA Capital serves as the investment adviser to the Fund, with Dr. Kolchinsky and Mr. Shah acting as controlling persons. The filing includes a certification that the shares were acquired in the ordinary course of business and not for the purpose of changing or influencing the control of the issuer. This filing establishes RA Capital as a major institutional shareholder following Altimmune's recent equity financing activity.