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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 ( Mark One ) 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 Class A Common Stock Class C Common Stock ( Title of each class ) Form 10 - K Maryland ( State or other jurisdiction of incorporation or organization ) 1020 Hull Street Baltimore , Maryland 21230 ( Address of principal executive offices ) ( Zip Code ) Commission File No. 001-33202 UNDER ARMOUR , INC . ( Exact name of registrant as specified in its charter ) ✓ 52-1990078 ( I.R.S. Employer Identification No. ) Securities registered pursuant to Section 12 ( b ) of the Act : UAA UA ( 410 ) 454-6428 ( Registrant's Telephone Number , Including Area Code ) New York Stock Exchange New York Stock Exchange ( Name of each exchange on which registered ) ( Trading Symbols ) 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 Act . Yes þ No ¨ 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 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 þ No No p 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 Accelerated filer Smaller reporting company Emerging growth company 0 0 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 No p Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes As of June 30 , 2020 , the last business day of our most recently completed second fiscal quarter , the aggregate market value of the registrant's Class A Common Stock and Class C Common Stock held by non - affiliates was $ 1,827,569,777 and $ 2,007,651,870 , respectively . As of January 31 , 2021 , there were 188,619,343 shares of Class A Common Stock , 34,450,000 shares of Class B Convertible Common Stock and 231,983,924 shares of Class C Common Stock outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of Under Armour , Inc.'s Proxy Statement for the Annual Meeting of Stockholders to be held on May 13 , 2021 are incorporated by reference in Part III of this Form 10 - K .