AMARIN CORP PLC\UK Stock Compensation Disclosure

On March 16, 2020, the Company’s Board of Directors, upon the recommendation of the Remuneration Committee, adopted, subject to shareholder approval, the 2020 Plan which was subsequently approved by the Company’s shareholders on July 13, 2020 at the Annual General Meeting of Shareholders. The 2020 Plan is the successor to the Company’s 2011 Plan, which was set to expire on July 12, 2021, and the Company’s 2002 Plan, the Plans.

The 2020 Plan allows the Company to grant stock options, both incentive and non-qualified options, to employees and Directors, restricted stock units to employees and unrestricted shares to Directors. The maximum number of the Company’s Ordinary Shares of £0.50 each or any ADS’s, as to be issued under the 2020 Plan shall not exceed the sum of (i) 20,000,000 Ordinary Shares and (ii) the number of Ordinary Shares that remained available for grants under the Company’s 2011 Plan as of July 13, 2020. If any award granted and outstanding under the Plans expires or is forfeited, surrendered, canceled or otherwise terminated, the shares may be made

available for subsequent grants under the 2020 Plan. The 2020 Plan is administered by the Remuneration Committee of the Company’s Board of Directors and expires on July 13, 2030.

Stock Options

Under the terms of the Plans, stock options typically vest over a three- or four-year period and expire after a 10-year term. The stock options are granted at an exercise price equal to the closing price of the Company’s ADSs on the grant date. The following table summarizes all stock option activity in Ordinary Shares for the year ended December 31, 2025:

The weighted average grant date fair value of stock options granted during the years ended December 31, 2025, 2024, and 2023 was $0.54, $0.57, and $1.27, respectively. The total grant date fair value of options vested during the years ended December 31, 2025, 2024, and 2023 was $5.7 million, $7.3 million, and $8.2 million, respectively.

During the year ended December 31, 2025, there were no options exercised. During the years ended December 31, 2024 and 2023, the Company received proceeds from the exercise of options of less than $0.1 million and $1.9 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2024 and 2023 was less than $0.1 million and $0.4 million, respectively, calculated as the difference between the quoted stock price of the Company’s Ordinary Shares as of the reporting date and the exercise prices of the underlying awards.

As of December 31, 2025, options have $3.8 million of unrecognized stock-based compensation expense with such expense expected to be recognized over a weighted-average period of approximately 3.6 years.

The fair value of stock options on the date of grant was estimated using the Black-Scholes option pricing model except for the market-based option awards which used the Monte Carlo option pricing model. Use of a valuation model requires management to make certain assumptions with respect to selected model inputs, which include:

Employee stock options generally require future service and vest ratably over a three or four-year service period and are settled by the issuance of new Ordinary Shares. The grant date fair value of the stock options, net of an estimated forfeiture rate is amortized straight-line over the awards’ vesting periods or respective requisite service periods and is adjusted for actual forfeitures over such period. The Company recorded compensation expense in relation to stock options of $4.4 million, $7.3 million, and $6.8 million for the years ended December 31, 2025, 2024, and 2023, respectively.

Restricted Stock Units

The restricted stock units vest based upon either a time-based service condition, a performance condition, or both. The grant date fair value of the restricted stock units, net of the estimated forfeiture rate, is amortized straight-line over the vesting periods or requisite service periods and is adjusted for actual forfeitures over such period. For any awards with a performance condition, the probability that any performance criteria will be achieved is assessed by management and compensation expense for such awards is only recorded to the extent that the attainment of the performance criteria is deemed to be probable.

The Company recorded compensation expense in relation to restricted stock units of $9.5 million, $10.4 million, and $9.8 million, for the years ended December 31, 2025, 2024, and 2023, respectively. The total grant date fair value of restricted stock units vested during the years ended December 31, 2025, 2024, and 2023 was $5.4 million, $9.3 million, and $16.3 million, respectively. As of December 31, 2025, restricted stock units have $4.4 million of unrecognized stock-based compensation expense with such expense to be recognized over a weighted-average period of approximately 0.9 years.

Employee Stock Purchase Plan

On March 13, 2017, the Board adopted, subject to shareholder approval, the Amarin Corporation plc 2017 Employee Stock Purchase Plan, or the ESPP, which was approved by the Company’s shareholders on May 15, 2017. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Internal Revenue Code. The maximum fair market value of stock which can be purchased by a participant in a calendar year is $25,000.

Under the ESPP, an aggregate of 3,000,000 Ordinary Shares (each ordinary share to be represented by twenty ADSs) are reserved and available for issuance, which were registered with the SEC on August 2, 2017, for sale to eligible employees. Subject to certain exclusions, any employee of the Company’s U.S. subsidiary, Amarin Pharma, Inc., who works at least 20 hours per week and has been employed for at least six months as of the first day of the applicable offering period is eligible to participate in the ESPP. Eligible employees may authorize payroll deductions of up to 15 percent of their base pay to be withheld to purchase ADSs, subject to terms and limitations of the plan, at a price equal to 85 percent of the lower of the fair market values of the Company’s ADSs as of the beginning or the end of six-month offering periods.

For the offering periods ended on the last business day on or before each of May 31, 2025 and November 30, 2025, the Company issued 97,520 and 104,200 Ordinary Shares, respectively, at a purchase price of $0.45 per share and $0.50 per share, respectively.

For the offering periods ended on the last business day on or before each of May 31, 2024 and November 30, 2024, the Company issued 139,982 and 116,766 Ordinary Shares, respectively, at a purchase price of $0.64 per share and $0.43 per share, respectively.

For the offering periods ended on the last business day on or before each of May 31, 2023 and November 30, 2023, the Company issued 205,861 and 113,749 Ordinary shares, respectively, at a purchase price of $1.01 per share and $0.66 per share, respectively.

As of December 31, 2025, 583,499 Ordinary Shares were reserved for future issuance under the ESPP.