Exploring Amarin Corporation plc (AMRN) Investor Profile: Who’s Buying and Why?

You've watched Amarin Corporation plc (AMRN) jump, but are you defintely sure who's driving the bus? The stock price is up a significant 42.32% since late 2024, hitting $16.21 a share as of November 2025, and yet the ownership structure is still upside down for a company with a flagship product like VASCEPA/VAZKEPA. Retail investors hold a massive 86.71% of the stock, which is a huge number that raises questions about volatility and conviction, especially when the company is in a turnaround, reporting Q3 2025 total net revenue of $49.7 million and a narrowed net loss of just $7.7 million. So, if retail is dominant, why are institutional players quietly stepping up, like Morgan Stanley, which increased its position by 65.472% in the third quarter of 2025? We need to map the motivations of the 102 institutional owners who are holding over 3.89 million shares against the backdrop of a debt-free balance sheet with $286.6 million in cash. Are they betting on the international partnered model, or is this a deep-value play on the core U.S. business? Let's dig into the 2025 filings to see who's buying and, more importantly, why they think the next chapter is worth the risk.

Who Invests in Amarin Corporation plc (AMRN) and Why?

The investor profile for Amarin Corporation plc (AMRN) is highly polarized, which is typical for a biotech company navigating a post-patent-loss turnaround. The short answer is: a massive retail base is holding on, while a few powerful institutional activists are driving the strategic change.

You need to know that the stock's price action is disproportionately influenced by the sentiment of individual investors, but the company's strategy is being dictated by activist hedge funds. This creates a volatile mix.

Key Investor Types: The High-Stakes Ownership Split

The ownership structure of Amarin Corporation plc is unusual because it has one of the highest concentrations of retail ownership you'll see in the sector. This means individual investors, not large financial institutions, hold the majority of the shares.

Here's the quick math on the breakdown:

• Retail Investors: Hold approximately 83.64% of the total shares outstanding.
• Institutional Investors: Hold around 12.46% of the stock, including mutual funds and hedge funds.
• Insiders: Own roughly 2.39%, which is a small but important alignment signal.

The sheer size of the retail base makes the stock susceptible to momentum swings, but the institutional slice, though smaller in percentage, holds the power. This is defintely a stock where the big money is activist money, not passive index money.

Investment Motivations: Turnaround and Global Growth

The primary motivation for institutional investors in 2025 is a classic turnaround play, centered on maximizing the global value of their flagship product, VASCEPA/VAZKEPA (icosapent ethyl). Retail investors, on the other hand, are often motivated by the drug's proven clinical data and the hope of a significant recovery from its post-generic lows.

The business case for the institutional money rests on two pillars:

• U.S. Cash Flow Stability: The U.S. product revenue was $40.9 million in Q3 2025, up 34% year-over-year, showing the core business is stabilizing and generating cash despite generic competition.
• International Growth Potential: The new strategic shift to a fully partnered commercial model across international markets is designed to accelerate growth outside the U.S. The company is targeting sustainable positive free cash flow in 2026, which is the key metric for these investors.

The company's goal is to move past the $7.7 million net loss reported in Q3 2025 by leveraging this new, leaner model. For more on the long-term vision driving this strategy, you can review the Mission Statement, Vision, & Core Values of Amarin Corporation plc (AMRN).

Investment Strategies: Activist Value and Deep-Dive Biotech

The strategies employed by the largest shareholders are highly focused, reflecting the company's distressed-but-recovering status. It's not a passive buy-and-hold situation; it's a hands-on, value-creation effort.

The most prominent strategy is Activist Value Investing. This is best exemplified by the largest institutional holder, Sarissa Capital Management LP, who successfully took control of the Board of Directors in early 2023. Their strategy is simple: unlock the perceived intrinsic value of the drug by forcing operational efficiency, cutting costs (like the significant 47% drop in Selling, General, and Administrative expenses following the June 2025 restructuring), and executing the global partner strategy.

Other major institutional players, like Kynam Capital Management, LP, employ a Long/Short Equity Strategy focused on the global healthcare and biotechnology sectors. They are deep-dive fundamental analysts who see Amarin Corporation plc as an undervalued asset in a sector they know well, likely betting on the success of the European commercialization and the potential for a strategic acquisition down the road.

Here is a look at the strategies tied to the major institutional money:

The core risk here is execution: the strategy is sound, but turning around a global commercial operation is a multi-year effort. You should monitor the licensing and royalty revenue, which was only $1.1 million in Q3 2025, as this is the early indicator of success for the new international partner model.

Institutional Ownership and Major Shareholders of Amarin Corporation plc (AMRN)

You're looking at Amarin Corporation plc (AMRN) and wondering who the big money is-the institutional investors-and what their movements tell us about the company's future. The direct takeaway is that institutional ownership is highly dynamic right now, showing a clear split between funds aggressively increasing their stakes and others making a sharp exit, often following the company's 20:1 reverse stock split.

As of the 2025 fiscal year, specifically the third quarter filings (September 30, 2025), institutions hold a total of approximately 3.89 million shares. While this represents a smaller percentage of the total float compared to some large-cap biopharma, their concentration and recent activity are what really matter. The total institutional ownership stands at about 22.25% of the stock.

Here's a snapshot of the top institutional holders as of the Q3 2025 reporting period. These are the funds whose investment decisions carry the most weight in the market:

The Dynamic of Ownership Changes: Who's Buying and Selling?

The institutional activity in the 2025 fiscal year is a classic battle between deep-value conviction and risk-off selling. You see huge percentage swings, which is typical for a biotech company navigating a major strategic shift. The most recent filings show a clear pattern of accumulation from certain funds, but also significant divestment from others. This tells you the market is defintely split on Amarin Corporation plc's future trajectory.

The buying side is strong. For example, Acadian Asset Management LLC significantly increased its stake by 89.415% in the third quarter, adding 215,532 shares. That's a huge vote of confidence. Also, Morgan Stanley boosted its position by 65.472% in the same period, acquiring an additional 106,697 shares. When a major investment bank like Morgan Stanley increases its exposure, it signals an internal belief that the stock has been oversold or that the turnaround plan is starting to stick.

But there's a flip side. Quinn Opportunity Partners LLC, for instance, sold off a massive 1,110,778 shares in the second quarter, reducing their stake by 95.0%. That kind of sharp cut suggests a complete loss of conviction in the near-term story. This mixed activity means volatility is likely to remain high, as these large trades can move the stock price significantly. Here's the quick math: a single sale of over a million shares puts serious downward pressure on a stock with a relatively small institutional float.

Institutional Influence on Stock and Strategy

The role of these large investors goes beyond just price movement; they are deeply involved in the company's strategy. When a fund like Sarissa Capital Management LP is a top holder, it's often not a passive investment. Funds that file a Schedule 13D with the SEC are saying they hold over 5% and intend to actively pursue a change in business strategy, which often means pushing for board seats, management changes, or a sale of the company.

The recent 20:1 reverse stock split, executed to maintain compliance with Nasdaq listing requirements, was a critical event. While necessary, it often signals struggle, and institutional investors typically react negatively, which explains some of the recent sell-offs. The institutional reaction is a headwind the company must overcome. The continued accumulation by other funds, however, suggests they see the post-split, lower-valuation stock as a deep-value opportunity, especially given the company's core asset, VASCEPA®/VAZKEPA® (Icosapent Ethyl). If you want to dive deeper into the company's fundamentals, you should check out Breaking Down Amarin Corporation plc (AMRN) Financial Health: Key Insights for Investors.

• Monitor 13D filings for signs of activist pressure.
• Watch for a continued rebound in the Fund Sentiment Score.
• Track the next quarterly filings to see if the Acadian Asset Management LLC and Morgan Stanley buying trend continues.

Key Investors and Their Impact on Amarin Corporation plc (AMRN)

You need to know who is really pulling the levers at Amarin Corporation plc (AMRN), and the short answer is a mix of powerful activist funds and a massive retail base. Institutional investors, while holding a smaller percentage of the total float-about 12.46% as of early 2025-drive the strategic direction, but the sheer volume of retail ownership (approximately 86.71%) creates a unique, volatile dynamic.

The Activist Anchor: Sarissa Capital and Board Control

The most influential investor is defintely Sarissa Capital Management LP, an activist fund that has been Amarin Corporation plc's largest institutional shareholder. Sarissa's stake is not just passive; they successfully won control of the board two years ago, which immediately triggered a significant corporate restructuring, including an estimated 120 layoffs to chop off about one-third of the company.

As of the most recent filings on September 30, 2025, Sarissa Capital Management Lp held a substantial position of 1,242,527 shares. This kind of board control means Sarissa's interests-focused on maximizing the global value of Vascepa/Vazkepa-are directly mapped onto the company's strategy, from European commercialization to cost management. The firm's presence acts as a permanent, high-pressure check on management's execution. It's a clear example of active ownership driving operational change, but it also ties the stock's fate closely to the fund's long-term vision. You can see the company's strategic focus in its Mission Statement, Vision, & Core Values of Amarin Corporation plc (AMRN).

Recent Institutional Buying and Selling Moves

The third quarter 2025 13F filings show a clear pattern of accumulation by specific hedge funds and asset managers, indicating a belief that the stock is undervalued at its 2025 price point, which was around $16.21 per share as of November 12, 2025.

Here's the quick math on who was buying and selling in the latest reporting period (ending 9/30/2025):

The aggressive accumulation by firms like Millennium Management Llc and Citadel Advisors Llc, increasing their stakes by 192.616% and 169.032% respectively, suggests a short-term catalyst or a belief in the company's turnaround plan, despite the net loss of $15.7 million reported for the first quarter of 2025. Conversely, the continued selling by others like SCP Investment, Lp shows not all institutional money is convinced yet.

The New Activist Threat and Insider Holdings

The activist story isn't over. In March 2025, a new shareholder group led by Bradley Radoff and Michael Torok (of JEC Capital Partners) emerged, collectively holding approximately 15 million shares, which represented about a 3.6% stake. This group publicly called for an immediate strategic review, arguing that the stock's performance had faltered even after Sarissa took over the board. This new pressure points to ongoing investor discontent and the potential for another proxy fight, which can create near-term stock volatility but also force management into value-creating actions like a sale or a major shift in focus.

On the insider front, James Healy is the largest individual shareholder, owning 18.92 million shares, representing 4.55% of the company. Insider holdings like this, valued at approximately $307.91 million, mean the interests of the board and management are heavily aligned with shareholder value, but it also concentrates power.

• Watch for new 13D filings; they signal activist intent.
• High insider ownership (16.26%) stabilizes the stock.
• Retail volume (86.71%) amplifies price swings.

Market Impact and Investor Sentiment

You're looking at Amarin Corporation plc (AMRN) and trying to figure out if the recent financial improvements have actually swayed the big money, and honestly, the picture is still mixed-to-negative, but with some very specific bright spots. The overall investor sentiment, according to technical indicators as of November 16, 2025, is still generally bearish, with 15 bearish signals against 11 bullish signals. The Fear & Greed Index for AMRN is sitting firmly in the Fear territory at 39, which tells you that most investors are still nervous about the long-term outlook.

Still, the insiders-the people who defintely know the business best-have shown a positive sentiment based on the timing and significance of recent acquisitions. This is a classic disconnect: the market is fearful, but the people running the company are buying. Institutional ownership is about 22.25% of the company, which is low for a mature biopharma, but the activity among those institutions is telling.

Here's a quick look at the conflicting institutional moves in 2025:

• Quinn Opportunity Partners LLC slashed its stake by 95.0% in Q2 2025, selling 1,110,778 shares.
• Acadian Asset Management LLC grew its position by 112.3%, adding over 2 million shares.
• Millennium Management Llc increased its holding by a massive 192.616% as of September 30, 2025.

Recent Market Reactions to Ownership Shifts

The stock market's response to Amarin Corporation plc's strategic shifts and financial reports in 2025 has been volatile, but with a recent upward trend. The biggest market event this year was the 1-for-20 reverse stock split on April 11, 2025, which aimed to boost the per-share price and avoid delisting, a necessary but often negative signal to the market.

However, the Q3 2025 earnings report released on October 29, 2025, provided a much-needed lift. The company reported total net revenue of $49.7 million, which significantly surpassed the estimated $43.1 million. The Earnings Per Share (EPS) came in at a loss of -$0.02, which was a massive improvement over the estimated loss of -$0.48. This beat on the top and bottom line, plus the 56% improvement in operating loss to $11.1 million, signaled that the global restructuring plan is starting to work, driving the stock price up 7.50% since a pivot bottom on November 4, 2025.

Analyst Perspectives on Key Investor Impact

If you look at the professional analyst community, the consensus rating for Amarin Corporation plc is a Strong Sell, which is a tough pill to swallow for current shareholders. This is based on a limited number of analysts, but it highlights the deep skepticism about the company's ability to navigate the generic competition for its key product, Vascepa/Vazkepa, in the US market.

The average 12-month price target from analysts is around $12.00, which, compared to the November 2025 trading price of approximately $16.34, implies a downside of over 26%. Goldman Sachs, for example, set a price target of $12.00 on June 25, 2025. The analysts are simply not yet convinced that the shift to a fully partnered international commercial model-which now covers nearly 100 countries-will be enough to offset the domestic revenue pressures quickly enough to reach sustainable profitability. The management is targeting positive free cash flow in 2026, so that's the key milestone everyone is watching.

Here's the quick math on the Q3 2025 performance that's driving the 'wait-and-see' analyst stance:

What this estimate hides is the potential for the new partnered model to deliver significant licensing and royalty revenue, which was up 149% in Q3 2025. You should keep a close eye on the Mission Statement, Vision, & Core Values of Amarin Corporation plc (AMRN), as their strategic focus on international expansion is the core of the turnaround story. The market is waiting for the numbers to prove the strategy is working, and until then, the average price target will likely remain low.

So, your clear action is to monitor the Q4 2025 report for continued expense reduction and a material increase in international licensing revenue, not just the initial product shipments to partners like Recordati.