EX-4.9



 Exhibit 4.9 

AMARIN CORPORATION PLC 

2017 EMPLOYEE STOCK PURCHASE PLAN 

The purpose of the Amarin Corporation plc Employee Stock Purchase Plan (“the Plan”) is to provide eligible employees of each
Designated Company (as defined in Section 11) of Amarin Corporation plc (the “Company”) with opportunities to purchase ordinary shares of £0.50 each (the “Ordinary Shares”) or American Depositary Shares, each
representing one Ordinary Share, as the case may be (the “Shares”). An aggregate of 3,000,000 Shares have been approved and reserved for this purpose. The Plan is intended to constitute an “employee stock purchase plan” within
the meaning of Section 423(b) of the Internal Revenue Code of 1986, as amended (the “Code”), and shall be interpreted in accordance with that intent. 

1.    Administration. The Plan will be administered by the person or persons (the “Administrator”)
appointed by the Company’s Board of Directors (the “Board”) for such purpose. The Administrator has authority at any time to: (i) adopt, alter and repeal such rules, guidelines and practices for the administration of the Plan and
for its own acts and proceedings as it shall deem advisable; (ii) interpret the terms and provisions of the Plan; (iii) make all determinations it deems advisable for the administration of the Plan; (iv) decide all disputes arising in
connection with the Plan; and (v) otherwise supervise the administration of the Plan. All interpretations and decisions of the Administrator shall be binding on all persons, including the Company and the Participants. No member of the Board or
individual exercising administrative authority with respect to the Plan shall be liable for any action or determination made in good faith with respect to the Plan or any option granted hereunder. 







 2.    Offerings. The Company will make one or more offerings to
eligible employees to purchase Shares under the Plan (“Offerings”). Unless otherwise determined by the Administrator, the initial Offering will begin on December 1, 2017 and will end on May 31, 2018 (the “Initial Offering”).
Thereafter, unless otherwise determined by the Administrator, an Offering will begin on the first business day occurring on or after each June 1st and December 1st and will end on the last business day occurring on or before the following May 31st and November
30th, respectively. The Administrator may, in its discretion, designate a different period for any Offering, provided that no Offering shall exceed six months in duration or overlap any other
Offering. 
 3.    Eligibility. All individuals classified as employees on the payroll records of each Designated
Company are eligible to participate in any one or more of the Offerings under the Plan, provided that as of the first day of the applicable Offering (the “Offering Date”) they are customarily employed by a Designated Company for more than
20 hours a week and have completed at least six months of employment. Notwithstanding any other provision herein, individuals who are not contemporaneously classified as employees of a Designated Company for purposes of the applicable Designated
Company’s payroll system are not considered to be eligible employees of any Designated Company and shall not be eligible to participate in the Plan. In the event any such individuals are reclassified as employees of a Designated Company for any
purpose, including, without limitation, common law or statutory employees, by any action of any third party, including, without limitation, any government agency, or as a result of any private lawsuit, action or administrative proceeding, such
individuals shall, notwithstanding such reclassification, remain ineligible for participation. Notwithstanding the foregoing, the exclusive means for individuals who are not contemporaneously classified as employees of a Designated Company on the
Designated Company’s payroll system to become eligible to participate in this Plan is through an amendment to this Plan, duly executed by the Company, which specifically renders such individuals eligible to participate herein. 

  
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 4.    Participation. 

(a)    An eligible employee who is not a Participant in any prior Offering may participate in an Offering by submitting an
enrollment form to his or her appropriate payroll location at least 15 business days before the Offering Date (or by such other deadline as shall be established by the Administrator for the Offering). 

(b)    Enrollment. The enrollment form will (a) state a dollar amount or whole percentage to be deducted from
an eligible employee’s Compensation (as defined in Section 11) per pay period, (b) authorize the purchase of Shares in each Offering in accordance with the terms of the Plan and (c) specify the exact name or names in which Shares
purchased for such individual are to be issued pursuant to Section 10. An employee who does not enroll in accordance with these procedures will be deemed to have waived the right to participate. Unless a Participant files a new enrollment form
or withdraws from the Plan, such Participant’s deductions and purchases will continue at the same amount or percentage of Compensation for future Offerings, provided he or she remains eligible. 

(c)    Notwithstanding the foregoing, participation in the Plan will neither be permitted nor be denied contrary to the
requirements of the Code. 
 5.    Employee Contributions. Each eligible employee may authorize payroll
deductions at a minimum of one percent up to a maximum of 15 percent of such employee’s Compensation for each pay period. The Company will maintain book accounts showing the amount of payroll deductions made by each Participant
for each Offering. No interest will accrue or be paid on payroll deductions. 

  
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 6.    Deduction Changes. Except as may be determined by the
Administrator in advance of an Offering, a Participant may not increase or decrease his or her payroll deduction during any Offering, but may increase or decrease his or her payroll deduction with respect to the next Offering (subject to the
limitations of Section 5) by filing a new enrollment form at least 15 business days before the next Offering Date (or by such other deadline as shall be established by the Administrator for the Offering). The Administrator may, in advance of
any Offering, establish rules permitting a Participant to increase, decrease or terminate his or her payroll deduction during an Offering. 

7.    Withdrawal. A Participant may withdraw from participation in the Plan by delivering a written notice of
withdrawal to his or her appropriate payroll location. The Participant’s withdrawal will be effective as of the next business day. Following a Participant’s withdrawal, the Company will promptly refund such individual’s entire account
balance under the Plan to him or her (after payment for any Shares purchased before the effective date of withdrawal). Partial withdrawals are not permitted. Such an employee may not begin participation again during the remainder of the Offering,
but may enroll in a subsequent Offering in accordance with Section 4. 
 8.    Grant of Options. On each
Offering Date, the Company will grant to each eligible employee who is then a Participant in the Plan an option (“Option”) to purchase on the last day of such Offering (the “Exercise Date”), at the Option Price hereinafter
provided for, the lowest of (a) a number of Shares determined by dividing such Participant’s accumulated payroll deductions on such Exercise Date by the Option Price (as defined below), (b) a number of Shares determined by multiplying
$2,083 by the number of full months in such Offering and dividing the result by the Fair Market Value of the Shares on the Offering Date; or (c) such other lesser 

  
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maximum number of Shares as shall have been established by the Administrator in advance of the Offering; provided, however, that such Option shall be subject to the limitations set forth below.
Each Participant’s Option shall be exercisable only to the extent of such Participant’s accumulated payroll deductions on the Exercise Date. The purchase price for each Share purchased under each Option (the “Option Price”) will
be 15 percent of the Fair Market Value of the Shares on the Offering Date or the Exercise Date, whichever is less. 
 Notwithstanding
the foregoing, no Participant may be granted an option hereunder if such Participant, immediately after the option was granted, would be treated as owning shares possessing five percent or more of the total combined voting power or value of all
classes of shares of the Company or any Parent or Subsidiary (as defined in Section 11). For purposes of the preceding sentence, the attribution rules of Section 424(d) of the Code shall apply in determining the share ownership of a
Participant, and all shares that the Participant has a contractual right to purchase shall be treated as shares owned by the Participant. In addition, no Participant may be granted an Option that permits his or her rights to purchase Shares under
the Plan, and any other employee stock purchase plan of the Company and its Parents and Subsidiaries, to accrue at a rate that exceeds $25,000 of the fair market value of such shares (determined on the option grant date or dates) for each calendar
year in which the Option is outstanding at any time. The purpose of the limitation in the preceding sentence is to comply with Section 423(b)(8) of the Code and shall be applied taking Options into account in the order in which they were
granted. 
 9.    Exercise of Option and Purchase of Shares. Each employee who continues to be a Participant in
the Plan on the Exercise Date shall be deemed to have exercised his or her Option on such date and shall acquire from the Company such number of whole Shares reserved for the 

  
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purpose of the Plan as his or her accumulated payroll deductions on such date will purchase at the Option Price, subject to any other limitations contained in the Plan. Any amount remaining in a
Participant’s account at the end of an Offering solely by reason of the inability to purchase a fractional Share will be carried forward to the next Offering; any other balance remaining in a Participant’s account at the end of an Offering
will be refunded to the Participant promptly. 
 10.    Issuance of Certificates. Certificates representing
Shares purchased under the Plan may be issued only in the name of the employee, in the name of the employee and another person of legal age as joint tenants with rights of survivorship, or in the name of a broker authorized by the employee to be
his, her or their, nominee for such purpose. 
 11.    Definitions. 

The term “Compensation” means the amount of base pay, prior to salary reduction pursuant to Sections 125, 132(f) or 401(k) of
the Code, but excluding overtime, commissions, incentive or bonus awards, allowances and reimbursements for expenses such as relocation allowances or travel expenses, income or gains on the exercise of Company stock options, and similar items. The
Administrator, in its discretion, may, on a uniform and nondiscriminatory basis, in advance of any Offering, establish a different definition of Compensation for that Offering and future Offerings. 

The term “Designated Company” means the Company and/or any present or future Subsidiary (as defined below), in each case, that has
been designated by the Board to participate in the Plan. The Board may so designate the Company and/or any Subsidiary, or revoke any such designation, at any time and from time to time, either before or after the Plan is approved by the
shareholders. The current list of Designated Companies is attached hereto as Appendix A. 

  
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 The term “Fair Market Value of the Shares” on any given date means the fair market
value of the Shares determined in good faith by the Administrator; provided, however, that if the Shares admitted to quotation on the National Association of Securities Dealers Automated Quotation System (“NASDAQ”), the NASDAQ Stock Market
or another national securities exchange, the determination shall be made by reference to the closing price on such date. If there is no closing price for such date, the determination shall be made by reference to the last date preceding such date
for which there is a closing price. 
 The term “Parent” means a “parent corporation” with respect to the Company, as
defined in Section 424(e) of the Code. 
 The term “Participant” means an individual who is eligible as determined in
Section 3 and who has complied with the provisions of Section 4. 
 The term “Subsidiary” means a “subsidiary
corporation” with respect to the Company, as defined in Section 424(f) of the Code. 
 12.    Rights on
Termination of Employment. If a Participant’s employment terminates for any reason before the Exercise Date for any Offering, no payroll deduction will be taken from any pay due and owing to the Participant and the balance in the
Participant’s account will be paid to such Participant or, in the case of such Participant’s death, to his or her designated beneficiary as if such Participant had withdrawn from the Plan under Section 7. An employee will be deemed to
have terminated employment, for this purpose, if the corporation that employs him or her, having been a Designated Company, ceases to be a Subsidiary, or if the employee is transferred to any corporation other than a Designated Company. An employee
will not be deemed to have terminated employment for this purpose, if the employee is on an approved leave of absence for military service or sickness or for any other purpose approved by the Company, if


  
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the employee’s right to reemployment is guaranteed either by a statute or by contract or under the policy pursuant to which the leave of absence was granted or if the Administrator otherwise
provides in writing. 
 13.    Special Rules. Notwithstanding anything herein to the contrary, the Administrator
may adopt special rules applicable to the employees of a particular Designated Company, whenever the Administrator determines that such rules are necessary or appropriate for the implementation of the Plan in a jurisdiction where such Designated
Company has employees; provided that such rules are consistent with the requirements of Section 423(b) of the Code. Any special rules established pursuant to this Section 13 shall, to the extent possible, result in the employees subject to
such rules having substantially the same rights as other Participants in the Plan. 
 14.    Optionees Not
Shareholders. Neither the granting of an Option to a Participant nor the deductions from his or her pay shall constitute such Participant a holder of the Shares covered by an Option under the Plan until such Shares have been purchased by and
issued to him or her. 
 15.    Rights Not Transferable. Rights under the Plan are not transferable by a
Participant other than by will or the laws of descent and distribution, and are exercisable during the Participant’s lifetime only by the Participant. 

16.    Application of Funds. All funds received or held by the Company under the Plan may be combined with other
corporate funds and may be used for any corporate purpose. 
 17.    Adjustment in Case of Changes Affecting
Shares. In the event of a subdivision of outstanding Shares, the payment of a dividend in Shares or any other change affecting the Shares, the number of Shares approved for the Plan and the Share limitation set forth in Section 8 shall be
equitably or proportionately adjusted to give proper effect to such event. 

  
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 18.    Amendment of the Plan. The Board may at any time and from time
to time amend the Plan in any respect, except that without the approval within 12 months of such Board action by the shareholders, no amendment shall be made increasing the number of Shares approved for the Plan or making any other change that would
require shareholder approval in order for the Plan, as amended, to qualify as an “employee stock purchase plan” under Section 423(b) of the Code. 

19.    Insufficient Shares. If the total number of Shares that would otherwise be purchased on any Exercise Date
plus the number of Shares purchased under previous Offerings under the Plan exceeds the maximum number of Shares issuable under the Plan, the Shares then available shall be apportioned among Participants in proportion to the amount of payroll
deductions accumulated on behalf of each Participant that would otherwise be used to purchase Shares on such Exercise Date. 

20.    Termination of the Plan. The Plan may be terminated at any time by the Board. Upon termination of the Plan,
all amounts in the accounts of Participants shall be promptly refunded. 
 21.    Governmental Regulations. The
Company’s obligation to sell and deliver Shares under the Plan is subject to obtaining all governmental approvals required in connection with the authorization, issuance, or sale of such Shares. 

22.    Governing Law. This Plan and all Options and actions taken thereunder shall be governed by, and construed in
accordance with, the laws of the State of New York, applied without regard to conflict of law principles. 

  
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 23.    Issuance of Shares. Shares may be issued upon exercise of an
Option from authorized but unissued Shares, from Shares held in the treasury of the Company, or from any other proper source. 

24.    Tax Withholding. Participation in the Plan is subject to any minimum required tax withholding on income of
the Participant in connection with the Plan. Each Participant agrees, by entering the Plan, that the Company and its Subsidiaries shall have the right to deduct any such taxes from any payment of any kind otherwise due to the Participant, including
Shares issuable under the Plan. 
 25.    Notification Upon Sale of Shares. Each Participant agrees, by entering
the Plan, to give the Company prompt notice of any disposition of Shares purchased under the Plan where such disposition occurs within two years after the date of grant of the Option pursuant to which such Shares were purchased or within one year
after the date such Shares were purchased. 
 26.    Effective Date and Approval of Shareholders. The Plan shall
take effect on the later of the date it is adopted by the Board and the date it is approved by the holders of a majority of the votes cast at a meeting of shareholders at which a quorum is present. 

  
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 APPENDIX A 

Designated Companies 
 Amarin
Pharma, Inc. 

  
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