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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 Form 10 - K ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to England and Wales ( State or other jurisdiction of incorporation or organization ) Amarin Corporation plc ( Exact name of registrant as specified in its charter ) Commission File No. 0-21392 77 Sir John Rogerson's Quay , Block C , Grand Canal Docklands , Dublin 2 , Ireland Title of each class American Depositary Shares ( ADS ( s ) ) , each ADS representing the right to receive one ( 1 ) Ordinary Share of Amarin Corporation plc ( Address of principal executive offices ) +353 ( 0 ) 1 6699 020 ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol AMRN Not applicable ( I.R.S. Employer Identification No. ) Name of each exchange on which registered NASDAQ Stock Market LLC NO ♫ Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . YES □ Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . YES □ Indicate by check mark whether the registrant ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . YES NO NO Π Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( § 232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . YES NO Accelerated filer Smaller reporting company Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or an emerging growth company . See the definitions of " large accelerated filer , " " accelerated filer , " " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . Large accelerated filer Non - accelerated filer Emerging growth company 0 If an emerging growth company , indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13 ( a ) of the Exchange Act . □ Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C. 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . YES □ NO The aggregate market value of the voting and non - voting common equity held by non - affiliates of the registrant as of June 30 , 2020 was approximately $ 2,644.9 million , based upon the closing price on the NASDAQ Capital Market reported for such date . 393,635,467 shares were outstanding as of February 19 , 2021 , including 393,436,525 shares held as American Depositary Shares ( ADSs ) , each representing one Ordinary Share , 50 pence par value per share , and 198,942 Ordinary Shares . DOCUMENTS INCORPORATED BY REFERENCE Certain information required to be disclosed in Part III of this report is incorporated by reference from the registrant's definitive proxy statement to be filed not later than 120 days after the end of the fiscal year covered by this report .