Amarin director Horn exercises RSUs into ADS

Amarin director Keith Horn exercised 838 Restricted Stock Units, converting them into 838 American Depositary Shares (ADS) on April 18, 2026 at a conversion price of $0 per share.

Rhea-AI Filing Summary

Amarin director Keith Horn exercised 838 Restricted Stock Units, converting them into 838 American Depositary Shares (ADS) on April 18, 2026 at a conversion price of $0 per share. In a related tax-withholding disposition, 403 ADS were delivered at $14.98 per share to cover taxes. Following these equity award transactions, he directly holds 836 ADS.

Insider Trade Summary

838 shares exercised/converted

Exercise 3 txns

Insider Horn Keith

Role Director

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Unit	838	$0.00	$0.00
Exercise	American Depositary Shares	838	$0.00	$0.00
Exercise Price or Tax Liability	American Depositary Shares	403	$14.98	$6K

Holdings After Transaction: Restricted Stock Unit — 838 contracts (Direct); American Depositary Shares — 836 shares (Direct)

Footnotes (5)

1. F1. Effective April 11, 2025, the Issuer implemented a ratio change that one (1) American Depositary Share ("ADS") currently represents twenty (20) Ordinary Shares ("ADS Ratio Change"). Proportionate adjustments were made to the Issuer's outstanding equity awards. The amount of securities reported on this Form 4 reflect the ADS Ratio Change.
2. F2. On April 18, 2024, following the conclusion of the Issuer's annual general meeting of shareholders for 2024, the Reporting Person was granted 2,514 RSUs under the Amarin Corporation plc 2020 Stock Incentive Plan (the "Plan"). These RSUs vest in three equal installments on each of April 18, 2025, April 18, 2026 and April 18, 2027.
3. F3. Not applicable.
4. F4. Represents withholding by the Issuer of shares in respect of tax liability incident to the vesting of a security issued in accordance with Rule 16b-3, and not a market sale of securities.
5. F5. Each RSU represents a contingent right to receive twenty Ordinary Shares or cash in lieu thereof at the Issuer's discretion.

Key Figures

RSUs exercised: 838 RSUs ADS acquired via conversion: 838 ADS Tax withholding shares: 403 ADS +4 more

7 metrics

RSUs exercised 838 RSUs Restricted Stock Units converted into ADS on April 18, 2026

ADS acquired via conversion 838 ADS American Depositary Shares received upon RSU exercise/conversion

Tax withholding shares 403 ADS Shares delivered to satisfy tax liability on April 18, 2026

Tax withholding price $14.98 per ADS Per-share value applied to ADS withheld for taxes

Post-transaction ADS holdings 836 ADS Direct ADS position after the reported transactions

RSUs granted under Plan 2,514 RSUs Grant on April 18, 2024 under Amarin Corporation plc 2020 Stock Incentive Plan

ADS to Ordinary Share ratio 1 ADS = 20 Ordinary Shares ADS Ratio Change effective April 11, 2025

Key Terms

Restricted Stock Unit, American Depositary Shares, Rule 16b-3, ADS Ratio Change, +1 more

5 terms

Restricted Stock Unit financial

"The Reporting Person was granted 2,514 RSUs under the 2020 Stock Incentive Plan"

A restricted stock unit is a promise from a company to give an employee shares of stock after certain conditions are met, like staying with the company for a set amount of time. It’s like earning a bonus that turns into company stock once you’ve proven your commitment, making it a way to motivate and reward employees.

American Depositary Shares financial

"One American Depositary Share currently represents twenty Ordinary Shares"

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.

Rule 16b-3 regulatory

"Security issued in accordance with Rule 16b-3, and not a market sale"

Rule 16b-3 is a Securities and Exchange Commission regulation that exempts certain routine, pre-approved transactions by company insiders from automatic liability for short-term trading profits. It acts like a safe harbor: if an insider follows a formal plan or the board approves specific transactions in advance, profits from buying and selling company stock within six months are not automatically reclaimed. Investors care because the rule clarifies when insider trades are permissible and reduces uncertainty about potential clawbacks.

ADS Ratio Change financial

"Represents twenty Ordinary Shares, described as the ADS Ratio Change"

An ads ratio change is an adjustment to how many American Depositary Shares (ADS) represent one unit of a foreign company’s ordinary shares — like changing whether a cake is cut into 2 or 10 slices. Investors care because it alters the number of tradable ADS, the implied price per ADS and an investor’s ownership stake, which can affect liquidity, perceived value and comparisons of holdings across markets.

contingent right financial

"Each RSU represents a contingent right to receive twenty Ordinary Shares or cash"

FAQ

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

What transactions did Amarin (AMRN) director Keith Horn report on this Form 4?

He reported converting 838 RSUs into the same number of American Depositary Shares and a tax-withholding disposition of 403 ADS at $14.98 per share. After these equity award-related events, he directly holds 836 ADS in Amarin.

How many Amarin (AMRN) American Depositary Shares does Keith Horn hold after these transactions?

Following the reported RSU conversion and tax-withholding disposition, Keith Horn directly holds 836 American Depositary Shares (ADS). This figure reflects his post-transaction position as disclosed in the holdings summary associated with the Form 4 data.

What RSU grant terms for Amarin (AMRN) are described in the Form 4 footnotes?

A footnote states Horn was granted 2,514 RSUs on April 18, 2024 under Amarin’s 2020 Stock Incentive Plan, vesting in three equal installments on April 18, 2025, 2026 and 2027. Each RSU represents a contingent right to receive twenty Ordinary Shares or cash.

How is the Amarin (AMRN) ADS to Ordinary Share ratio defined in this filing?

The footnotes explain that, effective April 11, 2025, one ADS currently represents twenty Ordinary Shares, described as an ADS Ratio Change. The amounts of securities reported in this Form 4 are adjusted to reflect that new ADS ratio.

Were Keith Horn’s Amarin (AMRN) transactions executed under a Rule 10b5-1 trading plan?

The filing’s Rule 10b5-1 checkbox is not marked as affirmative, indicating these events were not reported as being carried out under a pre-arranged Rule 10b5-1 trading plan but as routine equity award vesting and related tax-withholding transactions.

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

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Accepted by SEC EDGAR 04/21/2026 - 05:00 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Horn Keith

(Last) (First) (Middle)

C/O AMARIN PHARMA, INC.

440 US HIGHWAY 22

(Street)

BRIDGEWATER NEW JERSEY 08807

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
AMARIN CORP PLC\UK [ AMRN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/18/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
American Depositary Shares(1)	04/18/2026		M(2)		838(1)	A	(3)	1,239(1)	D
American Depositary Shares(1)	04/18/2026		F(4)		403(1)	D	$14.98	836(1)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Unit(5)	$0	04/18/2026		M		838(1)		(2)	(3)	American Depositary Shares(1)	838(1)	$0	838(1)	D

Explanation of Responses:

1. Effective April 11, 2025, the Issuer implemented a ratio change that one (1) American Depositary Share ("ADS") currently represents twenty (20) Ordinary Shares ("ADS Ratio Change"). Proportionate adjustments were made to the Issuer's outstanding equity awards. The amount of securities reported on this Form 4 reflect the ADS Ratio Change.

2. On April 18, 2024, following the conclusion of the Issuer's annual general meeting of shareholders for 2024, the Reporting Person was granted 2,514 RSUs under the Amarin Corporation plc 2020 Stock Incentive Plan (the "Plan"). These RSUs vest in three equal installments on each of April 18, 2025, April 18, 2026 and April 18, 2027.

3. Not applicable.

4. Represents withholding by the Issuer of shares in respect of tax liability incident to the vesting of a security issued in accordance with Rule 16b-3, and not a market sale of securities.

5. Each RSU represents a contingent right to receive twenty Ordinary Shares or cash in lieu thereof at the Issuer's discretion.

	/s/ Jonathan Provoost, by power of attorney	04/21/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)