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Table of Contents FORM 10 - K ( Mark One ) XANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended January 2 , 2021 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from Delaware ( Summit Materials , Inc. ) Delaware ( Summit Materials , LLC ) ( State or other jurisdiction of incorporation or organization ) 1550 Wynkoop Street , 3rd Floor Denver , Colorado ( Address of principal executive offices ) Title of each class Class A Common Stock ( par value $ .01 per share ) UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 Summit Materials , Inc. Summit Materials , LLC Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Summit Materials , Inc. Summit Materials , LLC Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Summit Materials , Inc. Large accelerated filer Non - accelerated filer Summit Materials , LLC Large accelerated filer Non - accelerated filer to Commission file numbers : 001-36873 ( Summit Materials , Inc. ) 333-187556 ( Summit Materials , LLC ) SUMMIT MATERIALS , INC . SUMMIT MATERIALS , LLC ( exact name of registrants as specified in their charters ) Registrants ' telephone number , including area code : ( 303 ) 893-0012 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) SUM Securities registered pursuant to Section 12 ( g ) of the Act : None □ ☑ Summit Materials , Inc. Summit Materials , LLC Summit Materials , LLC 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 . Summit Materials , Inc. Summit Materials , LLC T 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 ) . 47-1984212 26-4138486 ( I.R.S. Employer Identification No. ) 80202 ( Zip Code ) Name of each exchange on which registered New York Stock Exchange 1 Accelerated filer Smaller reporting company Emerging growth company In by check wh her 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 . Summit Materials , Inc. Summit Materials , LLC Accelerated filer Smaller reporting company Emerging growth company Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . 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 . Yes Yes Yes Yes Yes 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 . Yes Yes ooo 000 No No Yes Yes No No No No No X No No ☐ Yes □ No Yes No 00 U 00 00 The aggregate market value of the Summit Materials , Inc. voting stock held by non - affiliates of the Registrants as of June 27 , 2020 was approximately $ 1.7 billion . As of February 22 , 2021 , the number of shares of Summit Materials , Inc.'s outstanding Class A and Class B common stock , par value $ 0.01 per share for each class , was 114,796,060 and 99 , respectively . As of February 22 , 2021 , 100 % of Summit Materials , LLC's outstanding limited liability company interests were held by Summit Materials Intermediate Holdings , LLC , its sole member and an indirect subsidiary of Summit Materials , Inc. DOCUMENTS INCORPORATED BY REFERENCE