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 shares and (ii) the number of 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.

Under the terms of the Plans, stock options typically vest over a four-year period and expire after a ten-year term. The stock options are granted at an exercise price equal to the closing price of the Company’s American Depositary Shares on the grant date. The following table summarizes all stock option activity for the year ended December 31, 2022:


In thousands (except per share amounts and years)	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding as of January 1, 2022		18,493		$	7.32
Granted		5,038			2.56
Forfeited		(4,105	)		8.39
Expired		(211	)		11.65
Exercised		(33	)		1.79
Outstanding as of December 31, 2022		19,182			5.80	6.2 years	$	158
Exercisable as of December 31, 2022		12,888			6.80	4.9 years	$	86
Vested and expected to vest as of December 31, 2022		18,867			5.83	6.2 years	$	155
Available for future grant as of December 31, 2022		15,383

The weighted average grant date fair value of stock options granted during the years ended December 31, 2022, 2021, and 2020 was $2.56, $5.12, and $14.43, respectively. The total grant date fair value of options vested during the years ended December 31, 2022, 2021, and 2020 was $16.6 million, $21.1 million, and $22.5 million, respectively.

During the years ended December 31, 2022, 2021 and 2020, the Company received proceeds from the exercise of options of $0.1 million, $2.9 million, and $5.2 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2022, 2021, and 2020 was nominal, $4.9 million, and $9.0 million, respectively, calculated as the difference between the quoted stock price of the Company’s common stock as of the reporting date and the exercise prices of the underlying awards.

As of December 31, 2022, options have $13.5 million of unrecognized stock-based compensation expense with such expense expected to be recognized over a weighted-average period of approximately 2.1 years.

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

For 2022, 2021, and 2020, the Company used the following assumptions to estimate the fair value of share-based payment awards:


	2022	2021	2020
Risk-free interest rate	1.64% - 4.35%	0.53% - 1.36%	0.33% - 1.74%
Expected dividend yield	0.00%	0.00%	0.00%
Expected option life (years)	6.25	6.25	6.25
Expected volatility	96% - 101%	96% - 99%	84% - 99%

Employee stock options generally require future service and vest ratably over a four-year service period and are settled by the issuance of new common 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 $14.8 million, $23.0 million, and $22.4 million for the years ended December 31, 2022, 2021, and 2020, respectively.

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 unites, 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 following table presents the restricted stock unit activity for the year ended December 31, 2022 :


In thousands (except per share amounts)	Shares			Weighted Average Grant Date Fair Value
Outstanding as of January 1, 2022		9,277			7.70
Granted		12,587			2.97
Vested		(1,940	)		7.30
Forfeited		(5,463	)		6.79
Outstanding as of December 31, 2022		14,461		$	3.98

The Company recorded compensation expense in relation to restricted stock units of $11.4 million, $13.9 million, and $23.4 million for the years ended December 31, 2022, 2021, and 2020 respectively. As of December 31, 2022, restricted stock units have $23.7 million of unrecognized stock-based compensation expense with such expense to be recognized over a weighted-average period of approximately 2.2 years.

The following table presents the stock-based compensation expense related to stock-based awards for the years ended December 31, 2022, 2021, and 2020:


In thousands	2022			2021		2020
Research and development	$	4,465		$	4,327	$	6,568
Selling, general and administrative		22,339			32,305		39,245
Restructuring		(591	)		306		—
Stock-based compensation expense	$	26,213		$	36,938	$	45,813

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 one ADS) 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 ordinary shares, 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 ordinary shares 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, 2022 and November 30, 2022, the Company issued 265,214 shares and 191,482 shares, respectively, at a purchase price of $1.45 per share and $1.15 per share, respectively.

For the offering periods ended on the last business day on or before each of May 31, 2021 and November 30, 2021, the Company issued 226,402 shares and 172,884 shares, respectively, at a purchase price of $3.86 per share and $3.06 per share, respectively.

For the offering periods ended on the last business day on or before each of May 31, 2020 and November 30, 2020, the Company issued shares 123,608 shares and 223,545 shares, respectively, at a purchase price of $5.83 per share and $4.22 per share, respectively.

As of December 31, 2022, 1,361,577 shares were reserved for future issuance under the ESPP.