Join the Altimmune (ALT) Securities Class Action Lawsuit

Shamis & Gentile P.A., one of the nation's premier class action law firms specializing in securities fraud cases, is seeking a lead plaintiff in a securities class action lawsuit against Altimmune, Inc. (ALT)

If you purchased or acquired Altimmune, Inc. securities between August 10, 2023 and June 25, 2025, you may be eligible to join this class action lawsuit and seek compensation for your losses.

About Altimmune

Altimmune is a clinical-stage biopharmaceutical company based in Gaithersburg, Maryland, focusing on developing novel peptide-based therapeutics for obesity and liver diseases.

The company’s lead product candidate is pemvidutide, a GLP-1/glucagon dual receptor agonist, which is being developed for the treatment of obesity and metabolic dysfunction-associated steatohepatitis (MASH), also known as nonalcoholic steatohepatitis (NASH).

The Allegations

The securities class action lawsuit alleges that Altimmune and certain executives made materially false and misleading statements regarding the IMPACT Phase 2b MASH trial for pemvidutide.

Specifically, it is claimed that Altimmune provided overly optimistic expectations about the trial’s outcomes, while failing to disclose that the trial did not achieve statistical significance for the fibrosis reduction primary endpoint. This shortfall was reportedly due to a higher-than-expected placebo response, a critical detail that may not have been adequately communicated to investors.

Throughout the class period (from August 10, 2023 to June 25, 2025) Altimmune’s public statements and press releases continued to highlight positive prospects for pemvidutide, which allegedly led to an artificial inflation of the company’s stock price.

However, when Altimmune finally announced the topline results on June 26, 2025, revealing the failure to meet the key fibrosis reduction endpoint, the stock price dropped sharply by 53.2%. Shares fell from $7.71 on June 25, 2025 to $3.61 the following day, causing significant losses for investors.

Important Dates

• Class period: August 10, 2023 to June 25, 2025
• Lead plaintiff deadline: October 6, 2025
• Complaint filed: August 5, 2025

Your Rights and Next Steps

If you purchased or otherwise acquired Altimmune securities during the class period, you have important legal rights. Investors who suffered losses as a result of the alleged misconduct may be eligible to participate in the class action lawsuit and seek compensation.

You do not need to have sold your shares to qualify. If you choose to become a lead plaintiff, you can help direct the litigation. However, you are not required to be a lead plaintiff to participate in any potential recovery. The lead plaintiff deadline is October 6, 2025, so it’s important to act before this date if you wish to be considered for this role.

Lawyers are ready to help answer your questions, review your specific situation, and guide you through the process. There are no out-of-pocket costs to join the lawsuit, as fees and expenses are typically paid from any settlement or recovery.

You May Be Entitled to Compensation

If you invested in Altimmune during the class period and experienced financial losses, you may be entitled to compensation. To find out if you are eligible to join the lawsuit and to take the next step in seeking a recovery, complete the form below.

Lawyers are available to review your information and help you understand your options.