What happened

Amarin (AMRN 1.11%) stock shed 11.9% of its value this week, according to data provided by S&P Global Market Intelligence. The drugmaker's shares have been on the volatile side of late due to the ongoing public critique from its largest shareholder, Sarissa Capital, over the company's board of directors refreshment process. 

In brief, Sarissa is seeking to add seven directors to the board and to remove Chairman Per Wold-Olsen from the board, according to the company's press release. Amarin's management doesn't appear to be on board with this idea. 

So what

Sarissa released a statement on Jan. 10 calling Amarin's board refreshment process a "charade led by Chairman Per Wold-Olsen". Amarin responded the next day with a statement of its own, noting the company has actively engaged with Sarissa since the firm's outsize equity stake became public knowledge in November 2021.

The dispute escalated with Sarissa releasing another public critique of Amarin's management Wednesday. This time the drugmaker's largest stakeholder raised concerns about management's "slow, reactive responses to changing market dynamics" in the wake of the cardiovascular drug Vascepa losing patent protection in the U.S. 

Amarin's management responded Thursday, calling Sarissa's statements "misleading" and noting "they have no plan, no new ideas and their board candidates are not qualified." 

Now what

Sarissa Capital is headed up by noted activist investor Alex Denner. Denner has a long history of pressuring drugmakers to make leadership and strategic changes. Investors shouldn't be surprised by this turn of events.

That being said, it isn't entirely clear how this contentious back and forth will ultimately play out. As a result, investors ought to keep their focus squarely on the company's underlying fundamentals for the time being.