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Table of Contents ( Mark One ) ☐ ☑ ☐ UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 20 - F REGISTRATION STATEMENT PURSUANT TO SECTION 12 ( b ) or ( g ) OF THE SECURITIES EXCHANGE ACT OF 1934 OR 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 OR SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of event requiring this shell company report_ For the transition period from to Commission file number 001-36891 CELLECTIS S.A. ( Exact name of Registrant as specified in its charter ) ( Translation of Registrant's name into English ) Title of each class France ( Jurisdiction of incorporation or organization ) Cellectis S.A. 8 , rue de la Croix Jarry 75013 Paris , France ( Address of principal executive office ) Marie - Bleuenn Terrier General Counsel Cellectis S.A. 8 , rue de la Croix Jarry 75013 Paris , France Tel : +33 ( 0 ) 1 81 69 16 00 , Fax : +33 ( 0 ) 1 81 69 16 06 ( Name , Telephone , E - mail and / or Facsimile number and Address of Company Contact Person ) Securities registered pursuant to Section 12 ( b ) of the Act . American Depositary Shares , each representing one ordinary share , nominal value € 0.05 per share Ordinary shares , nominal value € 0.05 per share * Trading Symbol " CLLS " Name of each exchange on which registered Nasdaq Global Market Nasdaq Global Market *