Sarissa Capital reports 6.09% stake in Amarin

AMARIN CORP PLC/UK (AMRN) received Amendment No. 16 to a Schedule 13D from Sarissa Capital Management LP and Alexander J. Denner updating their ownership disclosure.

Rhea-AI Filing Summary

AMARIN CORP PLC/UK (AMRN) received Amendment No. 16 to a Schedule 13D from Sarissa Capital Management LP and Alexander J. Denner updating their ownership disclosure. The reporting persons may be deemed to beneficially own 25,743,900 Ordinary Shares, representing approximately 6.09% of Amarin’s outstanding Ordinary Shares.

The percentage is calculated based on 422,456,685 Ordinary Shares outstanding as of July 24, 2026, which includes 20,632,560 Ordinary Shares held as ADSs, each ADS representing 20 Ordinary Shares, as reported in Amarin’s Form 10-Q for the quarter ended June 30, 2026. All voting and dispositive power reported is shared rather than sole. The amendment also notes that transactions in the issuer’s securities within the past 60 days are listed in a new Exhibit 17.

Key Figures

Beneficial ownership: 25,743,900 Ordinary Shares Percent of class: 6.09% Shares outstanding: 422,456,685 Ordinary Shares +3 more

6 metrics

Beneficial ownership 25,743,900 Ordinary Shares Aggregate Ordinary Shares that the reporting persons may be deemed to beneficially own

Percent of class 6.09% Portion of Amarin’s outstanding Ordinary Shares represented by the reporting persons’ holdings

Shares outstanding 422,456,685 Ordinary Shares Ordinary Shares outstanding as of July 24, 2026, per Amarin’s Form 10-Q

Ordinary Shares held as ADSs 20,632,560 Ordinary Shares Ordinary Shares included in ADSs, each ADS representing 20 Ordinary Shares

Shared voting power 25,743,900 Ordinary Shares Ordinary Shares over which the reporting persons have shared voting power

Shared dispositive power 25,743,900 Ordinary Shares Ordinary Shares over which the reporting persons have shared dispositive power

Key Terms

Schedule 13D, American Depositary Shares, Ordinary Shares, beneficially own, +1 more

5 terms

Schedule 13D regulatory

"This Amendment No. 16 to ("Amendment No. 16") relates to American Depositary Shares"

A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.

American Depositary Shares financial

"relates to American Depositary Shares ("ADS(s)"), each ADS presently representing"

American depositary shares (ADSs) are a way for investors in the United States to buy shares of foreign companies without dealing with international markets directly. They represent ownership in a foreign company's stock and are traded on U.S. stock exchanges, making it easier for American investors to buy, sell, and own parts of companies from around the world.

Ordinary Shares financial

"ADS(s), each ADS presently representing twenty ordinary shares, par value 50 pence per share (the "Ordinary Shares")"

Ordinary shares are a type of ownership stake in a company, giving shareholders a right to participate in the company’s profits and decision-making through voting. They are similar to owning a piece of a business, and their value can rise or fall based on the company's performance. Investors buy ordinary shares to potentially earn dividends and benefit from the company's growth over time.

beneficially own financial

"The Reporting Persons may be deemed to beneficially own, in the aggregate, 25,743,900 Ordinary Shares"

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

dispositive power financial

"Shared Dispositive Power 25,743,900.00"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many AMRN shares does Sarissa Capital currently report owning?

Sarissa Capital Management LP and Alexander J. Denner report that they may be deemed to beneficially own 25,743,900 Ordinary Shares of Amarin. This figure includes Ordinary Shares underlying American Depositary Shares and reflects their aggregate beneficial ownership position.

What percentage of AMRN does Sarissa Capital’s stake represent?

Sarissa Capital and Alexander J. Denner report beneficial ownership of 6.09% of Amarin’s outstanding Ordinary Shares. This percentage is based on 422,456,685 Ordinary Shares outstanding as of July 24, 2026, as disclosed in Amarin’s Form 10-Q.

How many AMRN shares were outstanding when Sarissa’s 6.09% was calculated?

The reported 6.09% beneficial ownership is calculated using 422,456,685 Ordinary Shares outstanding as of July 24, 2026. This total includes 20,632,560 Ordinary Shares held as ADSs, each ADS representing 20 Ordinary Shares, as disclosed in Amarin’s Form 10-Q.

Does Sarissa Capital have sole or shared voting power over its AMRN stake?

The reporting persons state they have 0 Ordinary Shares with sole voting power and 25,743,900 Ordinary Shares with shared voting power. They similarly report shared dispositive power over 25,743,900 Ordinary Shares and no sole dispositive power.

What new information is added in Amendment No. 16 to Sarissa’s AMRN Schedule 13D?

Amendment No. 16 updates Item 2(b) (address information), Item 5(a) (beneficial ownership and percentage), Item 5(c) (recent transactions by reference to Exhibit 17), and Item 7 to add Exhibit 17 – Transactions in Securities.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/27/2026 - 06:57 PM EDT Accepted by SEC EDGAR 08/27/2026 - 06:56 PM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 16)

Amarin Corporation PLC/UK

(Name of Issuer)

Ordinary Shares, par value 50 pence per share

(Title of Class of Securities)

023111206

(CUSIP Number)

Alexander J Denner
Sarissa Capital Management LP, 500 West Putnam Avenue, Suite 400
Greenwich, CT, 06830
203-302-2330

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

08/25/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 023111206

1

Name of reporting person

Sarissa Capital Management LP

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 25,743,900.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 25,743,900.00

11

Aggregate amount beneficially owned by each reporting person

25,743,900.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

6.09 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s): 023111206

1

Name of reporting person

Alexander J Denner

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 25,743,900.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 25,743,900.00

11

Aggregate amount beneficially owned by each reporting person

25,743,900.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

6.09 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Ordinary Shares, par value 50 pence per share
(b)	Name of Issuer: Amarin Corporation PLC/UK
(c)	Address of Issuer's Principal Executive Offices: One Central Plaza, 5th Floor, 36 Dame Street, Dublin 2, IRELAND , D02 EF64.
Item 1 Comment: This Amendment No. 16 to Schedule 13D ("Amendment No. 16") relates to American Depositary Shares ("ADS(s)"), each ADS presently representing twenty ordinary shares, par value 50 pence per share (the "Ordinary Shares"), issued by Amarin Corporation plc, a company incorporated under the laws of England and Wales (the "Issuer"), and amends the initial statement on Schedule 13D filed with the Securities and Exchange Commission (the "SEC") on January 24, 2022 (the "Initial Schedule 13D"), as amended by Amendment No. 1 to Schedule 13D filed on June 3, 2022, Amendment No. 2 to Schedule 13D filed on June 16, 2022, Amendment No. 3 to Schedule 13D filed on October 11, 2022, Amendment No. 4 to Schedule 13D filed on January 11, 2023, Amendment No. 5 to Schedule 13D filed on January 19, 2023, Amendment No. 6 to Schedule 13D filed on February 8, 2023, Amendment No. 7 to Schedule 13D filed on February 10, 2023, Amendment No. 8 to Schedule 13D filed on February 14, 2023, Amendment No. 9 to Schedule 13D filed on February 15, 2023, Amendment No. 10 to Schedule 13D filed on February 21, 2023, Amendment No. 11 to Schedule 13D filed on February 27, 2023, Amendment No. 12 to Schedule 13D filed on February 28, 2023, Amendment No. 13 to Schedule 13D filed on September 5, 2023, Amendment No. 14 to Schedule 13D filed on December 5, 2023 and Amendment No. 15 to Schedule 13D filed on March 25, 2025 (the Initial Schedule 13D as so amended, the "Schedule 13D"). All capitalized terms contained herein but not otherwise defined shall have the meanings ascribed to such terms in the Schedule 13D. This Amendment No. 16 is being filed to amend Item 2(b), Item 5(a), Item 5(c) and Item 7 as follows:
Item 2.	Identity and Background
(b)	The address of the principal business and principal office of each of the Reporting Persons is c/o Sarissa Capital Management LP, 500 West Putnam Avenue, Suite 400, Greenwich, CT 06830.
Item 5.	Interest in Securities of the Issuer
(a)	The Reporting Persons may be deemed to beneficially own, in the aggregate, 25,743,900 Ordinary Shares representing approximately 6.09% of the outstanding Ordinary Shares. Percentages of the outstanding Ordinary Shares are based upon the 422,456,685 Ordinary Shares outstanding as of July 24, 2026, including 20,632,560 Ordinary Shares held as ADSs, each representing 20 Ordinary Shares, as set forth in the Form 10-Q of the Issuer filed with the SEC on July 29, 2026 for the quarterly period ended June 30, 2026.
(c)	Within the past 60 days, the Reporting Persons have transacted in the Issuer's securities as set forth in Exhibit 17, attached hereto and incorporated herein by reference.
Item 7.	Material to be Filed as Exhibits.
	Material to Be Filed as Exhibits. Item 7 is hereby amended to include the following: Exhibit 17 Transactions in Securities

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Sarissa Capital Management LP

Signature:	/s/ Alexander J Denner
Name/Title:	Alexander J Denner/Chief Investment Officer
Date:	08/27/2026

Alexander J Denner

Signature:	/s/ Alexander J Denner
Name/Title:	Alexander J Denner
Date:	08/27/2026