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Table of Contents ( Mark One ) Act . Act . 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 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Yes UNITED STATES Title of each class Common Stock , $ 0.001 par value For the transition period from Delaware ( State or other jurisdiction of incorporation or organization ) INFINITY PHARMACEUTICALS , INC . ( Exact name of registrant as specified in its charter ) 33-0655706 ( I.R.S. Employer Identification No. ) 1100 Massachusetts Avenue , Floor 4 , Cambridge , Massachusetts 02138 ( Address of principal executive offices ) ( zip code ) Registrant's telephone number , including area code : ( 617 ) 453-1000 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol INFI to Commission file number : 000-31141 Securities registered pursuant to Section 12 ( g ) of the Act : None Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities No X Large accelerated filer Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Yes No X Name of each exchange on which registered Nasdaq Global Select Market 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 Accelerated filer 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 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 definitions of “ large accelerated filer , ” “ accelerated filer , ” “ smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . Non - accelerated filer > Smaller reporting company Emerging growth company