🧾 What This Document Is

This is a prospectus supplement, a legal filing that adds the specific details of a new stock offering to a previously approved "shelf" registration. Think of it like a detailed menu addendum for a restaurant that already has a general license to serve food.

👉 In simple terms: Altimmune is using this document to officially announce it's selling a lot of new stock and warrants to raise money, and it's telling potential investors all the critical details and risks.

🏢 What The Company Does

Altimmune, Inc. (ticker: ALT) is a clinical-stage biopharmaceutical company. That means they're developing new drugs but don't have any on the market yet.

👉 In simple terms, they are a research-focused biotech company working on novel treatments for serious liver diseases. Their lead drug candidate is called pemvidutide.

Primary Target Disease: MASH (Metabolic dysfunction-associated steatohepatitis), a serious liver disease.
Additional Targets: They are also testing pemvidutide for Alcohol Use Disorder (AUD) and Alcohol-Associated Liver Disease (ALD).
Key Milestone: The FDA granted Breakthrough Therapy Designation for pemvidutide in MASH in December 2025, which is a big vote of confidence meant to speed up development.

🚀 The Offering: What's Being Sold

This is the core of the filing. Altimmune is raising capital through a complex sale of securities.

What's for sale:
1. Common Stock: 64.25 million new shares.
2. Common Stock Warrants: Warrants to buy up to 75 million more shares.
3. Pre-Funded Warrants: An alternative for some investors to buy warrants for up to 10.75 million shares (instead of the stock itself).
The Price: Each unit (a share or a pre-funded warrant plus a common warrant) is being sold to the public for $3.00. The underwriters get a discount of $0.18 per unit.
The Warrants: These are the right to buy stock later.
- Exercise Price: $3.00 per share.
- When they expire: The earlier of (i) 5 years from issuance, or (ii) 45 days after Altimmune announces positive Phase 3 trial results for pemvidutide in MASH. This ties the warrant's life directly to a major company milestone.
Total Raised: The gross proceeds are about $225 million.

👉 Why it matters: This is a significant cash raise for a clinical-stage company. It will fund operations for the near future but will also dilute existing shareholders by increasing the total number of shares.

💊 Pipeline & Clinical Trials: The Pemvidutide Story

The company's value hinges on pemvidutide. Here’s the latest data they highlight:

MASH (Phase 2b IMPACT Trial):
- 24-Week Results (June 2025): Showed strong efficacy. 58.2% of patients on the 1.2mg dose achieved MASH resolution (vs. 19.9% on placebo). It also showed signs of reducing liver scarring (fibrosis).
- 48-Week Results (Dec 2025): Confirmed continued improvement in non-invasive tests for liver fibrosis and ongoing weight loss with no plateau.
- Safety: Very favorable, with extremely low discontinuation rates due to side effects.
Alcohol Use Disorder (RECLAIM Phase 2 Trial):
- Enrollment is complete, and topline results are expected in 2026. The FDA gave this program Fast Track designation.
Alcohol-Associated Liver Disease (RESTORE Phase 2 Trial):
- Started enrolling patients in July 2025. This is a longer, 48-week trial.

👉 What this signals: The clinical data, especially the Breakthrough Therapy designation, is the primary reason investors might be interested. The upcoming RECLAIM trial results in 2026 are a major near-term catalyst.

💰 Financial Highlights & Use of Proceeds

Cash Need: As a clinical-stage biotech, Altimmune burns cash to fund research and trials. This raise provides a critical war chest.
Use of Proceeds: The filing states the money is for "general corporate purposes." This includes funding research and clinical development for pemvidutide and other candidates, working capital, and capital expenditures. They have broad discretion on how to spend it.
Stock Price Context: The offering price of $3.00 per share is below the last trading price of $3.47 on April 22, 2026. Selling new stock below the market price is common in these deals but is immediately dilutive.

⚖️ Big Picture: Strengths & Risks

👍 Strengths / Bull Case:

Promising Pipeline: Pemvidutide has strong Phase 2 data and the coveted Breakthrough Therapy designation for MASH.
Multiple Shots on Goal: Targeting MASH, AUD, and ALD with one drug diversifies risk.
Funded for Catalysts: This raise ensures they have the cash to reach key milestones like the RECLAIM trial results in 2026.

⚠️ Risks / Bear Case:

Clinical Trial Risk: The most important risk. Future Phase 3 trials could fail, rendering the drug worthless. The warrant expiration being tied to Phase 3 results underscores this binary risk.
Dilution: This offering significantly increases the share count, reducing each existing share's ownership percentage.
No Revenue: The company has no approved products and is not profitable. It relies entirely on investor funding.
Market Competition: The MASH space is highly competitive, with many other companies developing treatments.

🔮 What's Next

The company's roadmap is clear:

Continue Funding: Close this offering and put the capital to work.
Report Trial Data: The most important upcoming event is the topline data from the RECLAIM Phase 2 trial for AUD in 2026.
Plan for Phase 3: Based on ongoing results, they will need to design and fund expensive Phase 3 trials for pemvidutide, which is the final step before seeking FDA approval.

🧠 The Analogy

Altimmune is like a small restaurant that has created a fantastic, award-winning recipe (pemvidutide with strong Phase 2 data). They've received a glowing review from a famous food critic (FDA Breakthrough designation). Now, they need to raise money from investors to build a full kitchen and open a chain of restaurants (run Phase 3 trials) to prove the recipe works at scale and can be mass-produced for the public. This stock offering is them selling shares in their restaurant expansion project. The success of the entire venture depends on whether customers in the new restaurants love the recipe as much as the critics did.

🧩 Final Takeaway

Altimmune is raising ~$225 million by selling stock and warrants to fund the critical next phase of developing its promising liver disease drug, pemvidutide. This is a high-risk, high-reward investment where the value almost entirely depends on the success or failure of upcoming clinical trials, with the 2026 AUD trial results being the next major checkpoint.

ALT raises $225 million selling stock and warrants to fund development