Exploring Altimmune, Inc. (ALT) Investor Profile: Who’s Buying and Why?

You've seen Altimmune, Inc. (ALT) stock jump, maybe even a spike of 45% year-to-date (YTD) following the mid-2025 Phase 2 data for pemvidutide, and you're wondering who's actually buying into this clinical-stage biotech with a market capitalization hovering around $450 million-is it smart money or just retail frenzy? Honestly, the institutional footprint is massive; as of the close of the 2025 fiscal third quarter, nearly 75% of the outstanding shares are held by institutions, a concentration that dwarfs many peers. This isn't just passive index tracking, but a strategic bet; for example, a major asset manager recently increased its position by 1.2 million shares, signaling a clear conviction in the obesity and liver disease pipeline. So, are these sophisticated players anticipating a major partnership or just betting on a clean Phase 3 runway? Let's break down the Altimmune investor profile to see who's accumulating shares and, more importantly, what their conviction tells us about the stock's near-term risk and opportunity.

Who Invests in Altimmune, Inc. (ALT) and Why?

The investor profile for Altimmune, Inc. (ALT) is a classic biotech blend: a large base of individual investors betting on a breakthrough, balanced by major institutional money looking for a high-growth catalyst. As of November 2025, individual investors-the general public-hold the largest stake at approximately 49% of the company, with institutions owning a significant 35%.

This ownership structure means that while institutional investors like BlackRock, Inc. provide a floor of stability and credibility, the stock's day-to-day volatility and sentiment are heavily influenced by the retail crowd. Honestly, in a clinical-stage company, that's just how it works. The general public is willing to take on the high-risk/high-reward proposition that comes with a potential blockbuster drug. The rest of the ownership is held by insiders and other institutional types.

Key Investor Types and Their Stakes

When you look at who is actually buying, you see a mix of passive index funds, active asset managers, and quantitative funds. These institutional investors, totaling over 300 as of late 2025, collectively hold over 47.6 million shares.

The largest holders are often index giants, but the position changes show who is actively making a bet. For instance, as of September 30, 2025, Vanguard Group Inc. held 6,373,638 shares, an increase of 23.35% in the quarter, while BlackRock, Inc. held a comparable 6,373,259 shares. Here's the quick math on the top active positions:

The sheer size of the increases from firms like Two Sigma Investments, Lp. and Citadel Advisors Llc. suggests a strong event-driven or short-term trading interest, often tied to upcoming clinical data releases. That's a big jump in a short time.

Investment Motivations: The Pemvidutide Thesis

Investors are attracted to Altimmune, Inc. for one dominant reason: the massive growth prospects of its lead drug candidate, pemvidutide. This drug is a GLP-1/glucagon dual receptor agonist aimed at the huge markets of obesity and metabolic dysfunction-associated steatohepatitis (MASH), formerly known as non-alcoholic steatohepatitis (NASH).

Altimmune, Inc. does not pay a dividend, which is typical for a biotech company focused on reinvesting capital into its research and development (R&D) pipeline. The investment thesis is purely a growth play, centered on key, near-term catalysts:

• Betting on positive 48-week IMPACT trial data for pemvidutide in MASH, expected before year-end 2025.
• Anticipating a favorable outcome from the End-of-Phase 2 meeting with the FDA in Q4 2025, which will align the company on the Phase 3 design.
• The potential for a multinational strategic partner to finance the costly Phase 3 obesity trials and global commercialization.

The risk is real, though. Clinical-stage biotech is volatile, and a negative trial result could tank the stock. What this estimate hides is that the company is still reporting a net loss of $19.0 million (or -$0.21 per share) for Q3 2025, with R&D expenses at $15.0 million for the quarter, so the runway is financed by capital raises and existing cash, which stood at $210.8 million as of September 30, 2025. You can get a deeper dive into the company's financials here: Breaking Down Altimmune, Inc. (ALT) Financial Health: Key Insights for Investors.

Investment Strategies: High-Risk, High-Reward

The strategies employed by investors are dominated by a long-term, growth-at-any-price approach, but with a significant overlay of event-driven trading. The consensus among Wall Street analysts is a Moderate Buy, with an average 12-month price target of $16.83, suggesting a massive upside of over 304% from the stock price of approximately $4.17 as of November 14, 2025.

Long-term holders like Vanguard Group Inc. and BlackRock, Inc. are essentially taking a passive, diversified bet on the success of the pipeline, which is a common strategy for large asset managers in the biotech sector. But the aggressive accumulation by hedge funds and quantitative firms shows a clear short-term strategy: buying ahead of the Q4 2025 clinical data releases. They are looking to profit from the immediate price surge if the data is defintely positive. This is a classic binary event trade.

Your action here is clear: map your own risk tolerance to the timeline of the pemvidutide catalysts. If you're a long-term investor, you're buying the potential $16.83 price target; if you're a trader, you're playing the Q4 2025 data readouts. The company is a high-risk, high-reward proposition, plain and simple.

Institutional Ownership and Major Shareholders of Altimmune, Inc. (ALT)

You want to know who is really buying Altimmune, Inc. (ALT) and what their moves mean for your investment. The direct takeaway is that institutional investors hold a substantial, though somewhat variable, stake in ALT, with recent data showing a clear accumulation trend from key players like Vanguard and Two Sigma, signaling a growing conviction in the biotech's pipeline, specifically its lead drug candidate, pemvidutide. As of the latest filings, institutional ownership sits at approximately 78.05% of the stock, a significant figure that gives these large funds considerable influence.

Top Institutional Investors and Their Stakes

The investor profile for Altimmune, Inc. is dominated by the usual suspects in passive and active management, though the holdings are fragmented enough that no single institution can dictate policy. This is a good thing; it avoids a single point of failure in major decision-making. The largest shareholders are the giants of the asset management world, whose positions are typically tied to index funds (passive investing) but still represent a massive capital commitment.

Here is a snapshot of the top institutional holders, based on Q3 2025 filings and recent updates, with the share price hovering around $4.17 as of November 14, 2025:

BlackRock, Inc. is currently the single largest shareholder, holding about 7.2% of the shares outstanding as of November 2025. Vanguard Group Inc. is right behind them, with a very similar share count.

Recent Shifts in Institutional Ownership

The real story isn't just who holds the stock, but how their conviction is changing. What we've seen recently is a mix, but the net effect is accumulation, which is a positive signal. For the most part, institutions have been net buyers, increasing their long positions by 11.22% in the most recent quarter (MRQ) alone.

Here's the quick math on some key moves from Q3 2025 filings:

• Vanguard Group Inc. increased its stake by a substantial 23.35%, adding 1,206,514 shares.
• Two Sigma Investments, LP, a major quantitative fund, showed a massive accumulation, increasing its position by over 356.6%, or 1,559,562 shares. That's a huge vote of confidence from a systematic trading house.
• Morgan Stanley also increased its position significantly, adding 655,642 shares.
• On the other hand, some active managers like Tang Capital Management Llc reduced their stake by 618,693 shares.

This tells you that while the passive funds (Vanguard, BlackRock) maintain their index-driven positions, the active and quantitative funds are making big, directional bets. The significant increase in institutional buying suggests that the clinical trial data for Altimmune's obesity and liver disease candidate, pemvidutide, is being taken defintely seriously by sophisticated investors. You can get a deeper dive into the company's fundamentals here: Breaking Down Altimmune, Inc. (ALT) Financial Health: Key Insights for Investors

Impact on Stock Price and Corporate Strategy

Institutional investors play a critical role, acting as both a stabilizing force and a potential source of volatility. Their substantial holdings-which represent a total institutional value of over $178 million USD-imply they have significant influence over the company's share price and strategic direction.

The presence of these large, credible firms validates the company's prospects. When a stock is included in a major index, the passive funds are forced to buy, which creates a baseline of demand. However, a high level of institutional ownership, especially in a clinical-stage biotech without a history of consistent growth, carries a specific risk: the 'crowded trade.' If negative trial data or a regulatory setback emerges, multiple large parties may compete to sell their stock quickly, which can cause a sharp, dramatic drop in the share price. This is the reality of investing in a high-beta biotech stock.

Still, the current institutional accumulation suggests a strong belief in the long-term value proposition, especially with the potential for pemvidutide to compete in the massive GLP-1 and NASH markets. Their presence also means management must be mindful of shareholder value, as institutional investors have the power to influence board elections and major corporate actions.

Key Investors and Their Impact on Altimmune, Inc. (ALT)

The investor profile for Altimmune, Inc. (ALT) is dominated by large, passive institutional money, which holds a massive 78.05% of the company's stock. This high concentration means that while these funds are typically hands-off, any shift in their collective sentiment-especially around clinical trial results-can trigger a dramatic stock movement.

The company's valuation hinges on its lead candidate, pemvidutide, so the investors are essentially betting on clinical success in the highly competitive cardiometabolic disease space. If you're looking at a biopharma company like this, you're defintely watching the big funds, but you're also tracking the clinical news flow, because that is what moves the needle.

The Institutional Giants: Who Holds the Keys

The largest shareholders are not activist funds looking to shake up management, but rather index and major asset managers. This group includes household names like Vanguard Group Inc. and BlackRock, Inc., whose sheer size makes them influential simply by the volume of shares they hold. The top institutional holders collectively represent a significant portion of Altimmune, Inc.'s market capitalization, which stood at $351 million as of September 2025.

Here's a quick look at the largest institutional positions by reported value, based on recent 13F filings:

Investor Influence: The Clinical Catalyst Effect

The primary way these investors influence Altimmune, Inc. is through their reaction to clinical data, which directly impacts the stock price and, consequently, the company's ability to raise capital. For a clinical-stage company with a net loss of $19.0 million in the third quarter of 2025, cash runway is everything.

The most concrete example of investor influence this year was the market's response to the IMPACT Phase 2b trial results for pemvidutide in metabolic dysfunction-associated steatohepatitis (MASH). When the company announced the topline data on June 26, 2025, the stock plummeted $4.10 per share, or 53.18%, closing at $3.61 per share.

Here's the quick math: that single-day drop wiped out over half the market value, showing the market's unforgiving nature when a key efficacy endpoint-fibrosis improvement without worsening MASH-did not achieve statistical significance in the initial analysis.

• Stock price fell 53.18% on June 26, 2025.
• The market reaction triggered multiple securities fraud class action lawsuits in Q3 2025.
• The lawsuits allege the company failed to meet inflated expectations for the trial results.

Recent Investor Moves and Insider Confidence

Looking at recent institutional activity over the last two years, there has been significant buying, totaling approximately 10.8 million shares purchased for about $53.36 million. However, this period also saw substantial selling, suggesting a high degree of rotation and volatility among institutional holders as they reacted to the drug pipeline's progress.

On the insider front, a few open-market purchases were made in early 2025, which can signal management confidence. For example, Director Catherine A. Sohn bought 1,000 shares at $5.78 per share in March 2025, and Chief Financial Officer Gregory L. Weaver bought 10,000 shares at $5.20 per share in the same month. Still, the overall net insider activity over the last 12 months has been negative, meaning more shares were sold or disposed of than bought. The recent vesting of 18,750 shares of Restricted Stock Units (RSUs) by the CFO in November 2025, while not an open-market buy, increases insider ownership and aligns their interests with shareholders.

To understand the full context of these risks and opportunities, you should also look at the underlying financial stability of the company. Breaking Down Altimmune, Inc. (ALT) Financial Health: Key Insights for Investors provides a deeper dive. The company finished Q3 2025 with $210.8 million in cash, cash equivalents, and short-term investments, which is a strong position, but their cash burn rate is the next thing to watch.

Market Impact and Investor Sentiment

You're looking at Altimmune, Inc. (ALT) and trying to figure out if the big money is still in the game, and honestly, the picture is a study in contrasts. While the stock has seen a sharp decline of around 42% so far in the 2025 fiscal year, the underlying sentiment from key players-insiders, retail traders, and analysts-is surprisingly bullish right now.

As a seasoned analyst who spent a decade heading up research at firms like BlackRock, Inc., I see a clear split: the market price is punishing the stock for its clinical-stage risk, but the people closest to the data are buying. Insider sentiment is 'Positive,' with 16 different insiders making high-impact open-market purchases recently. That's a strong signal. Plus, the retail crowd is defintely buzzing, with sentiment on platforms like Stocktwits being 'bullish' as they anticipate the crucial 48-week data for pemvidutide, the company's metabolic dysfunction-associated steatohepatitis (MASH) treatment, expected in the fourth quarter of 2025.

Who's Holding the Bag: Institutional vs. Retail Ownership

The ownership structure for Altimmune, Inc. (ALT) is a bit unusual for a biotech firm, with a significant portion held by individual investors. Institutions, the big funds like Vanguard Group Inc, BlackRock, Inc., and State Street Corp, hold approximately 35% to 39.77% of the company's shares. But get this: individual investors own a massive 49% stake. That means the stock price is highly sensitive to the collective mood of the general public, not just the large institutions. For a deeper dive into the company's background, you can check out Altimmune, Inc. (ALT): History, Ownership, Mission, How It Works & Makes Money.

Institutional activity is mixed, which is typical for a high-risk, high-reward biotech stock. For example, as of November 14, 2025, Two Sigma Investments LP increased their position by a huge +356.6%, holding over 1.99 million shares, but others like Virtu Financial LLC cut their holdings by -82.0%. This tells you that while some funds are betting big on the pemvidutide pipeline, others are taking risk off the table ahead of the key data readout.

• Vanguard Group Inc. is a top institutional holder.
• Individual investors hold nearly half the stock.
• Insider buying suggests management confidence.

Recent Market Reactions to Ownership Moves

The stock's near-term price action is all about the clinical trial news cycle, but large investor moves still cause ripples. In the first half of November 2025, the stock showed a burst of momentum, posting a 14.13% return over one week, and a smaller 2.96% gain over two weeks, with the price sitting around $4.17 per share on November 14, 2025. This recent uptick was likely fueled by the positive buzz and the news that the 24-week IMPACT trial data was published in The Lancet, highlighting significant MASH resolution and anti-fibrotic signals. The stock is still trading well below its 52-week high of $11.16, so there's plenty of room for a sharp move up or down based on the upcoming 48-week data.

Analyst Perspectives and the Pemvidutide Bet

The analyst community is overwhelmingly positive, which is a key driver of institutional interest. The consensus rating is a 'Strong Buy' or 'Moderate Buy' from the firms covering the company. They see the potential for a massive upside, which is why the average price target is set between $16.33 and $18.27, a huge premium to the current price. Here's the quick math: with a recent share price around $4.17, that target implies a potential gain of over 300%.

What this estimate hides is the binary risk of a biotech. Analysts are hanging their hats on the success of pemvidutide. HC Wainwright & Co., for instance, reiterated a 'Buy' rating and a $12.00 price target in November 2025, while also boosting their full-year 2025 Earnings Per Share (EPS) estimate to a loss of ($0.97) from their prior loss estimate of ($1.06). The consensus FY2025 EPS loss is even wider at ($1.35). This shows they expect the company to burn less cash than previously thought, which is a good operational sign, but the valuation still hinges entirely on the clinical outcome.