Altimmune, Inc. Faces Class Action Lawsuit Over Alleged Misleading Statements Regarding IMPACT Phase 2b MASH Trial Results

A class action lawsuit has been filed against Altimmune, Inc. (NASDAQ: ALT) on behalf of investors who purchased or acquired the company's securities between August 10, 2023, and June 25, 2025. The lawsuit alleges that Altimmune misled investors regarding the viability of its IMPACT Phase 2b MASH trial, which tested the efficacy of Pemvidutide in treating MASH. On June 26, 2025, Altimmune announced the trial results, which failed to achieve statistical significance due to a higher-than-expected placebo response. As a result, the company's stock price plummeted by over 53% in a single day.

Key Takeaways:

• The class action lawsuit alleges that Altimmune misled investors regarding the viability of its IMPACT Phase 2b MASH trial.
• The trial tested the efficacy of Pemvidutide in treating MASH, but the results failed to achieve statistical significance.
• The company's stock price fell by over 53% on June 26, 2025, following the announcement of the trial results.
• Shareholders are eligible to participate in the class action and may be able to recover losses.
• The lead plaintiff is required to submit papers with the court by October 6, 2025, to serve as a representative for the class.
• Representation is on a contingency fee basis, with no fees or expenses for shareholders.

Statistics:

• 53%: The decline in Altimmune's stock price on June 26, 2025, following the announcement of the trial results.
• August 10, 2023: The start of the class period for the alleged misleading statements.
• June 25, 2025: The end of the class period for the alleged misleading statements.
• June 26, 2025: The date on which Altimmune announced the trial results.
• October 6, 2025: The deadline for the lead plaintiff to submit papers with the court.

Sources:

• [Robbins LLP press release, August 20, 2025]
• [Altimmune, Inc. SEC filings]
• [SEC Guidelines for Class Action Lawsuits]