Viking Global Investors LP Reports 6.7% Stake in Altimmune, Inc. Following Underwritten Offering

On May 1, 2026, Viking Global Investors LP (VGI) and its affiliates filed a Schedule 13G reporting a new 6.7% stake in Altimmune, Inc. (ALT). The reporting group, which includes Viking Global Opportunities Parent GP LLC, O. Andreas Halvorsen, and Rose S. Shabet, disclosed beneficial ownership of 13,400,000 shares of common stock. This total consists of 6,700,000 shares held directly and 6,700,000 shares obtainable through the exercise of warrants at $3.00 per share. The acquisition followed an underwritten offering by the issuer that closed on April 24, 2026. Within the group, Viking Global Opportunities Illiquid Investments Sub-Master LP (VGOP) holds a 4.7% interest, while Viking Global Opportunities Vintage IV (Aggregator) LP holds a 2.0% interest. VGI provides managerial services to these entities and maintains shared voting and dispositive power over the securities. The filing indicates the shares were acquired for investment purposes and not to influence control of the issuer.