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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 Commission File Number : 1-33409 T Mobile T - MOBILE US , INC . ( Exact name of registrant as specified in its charter ) Delaware ( State or other jurisdiction of incorporation or organization ) Title of each class Common Stock , par value $ 0.00001 per share 12920 SE 38th Street Bellevue , Washington ( Address of principal executive offices ) 98006-1350 ( Zip Code ) ( 425 ) 378-4000 ( I.R.S. Employer Identification No. ) ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : 20-0836269 Trading Symbol TMUS Securities registered pursuant to Section 12 ( g ) of the Act : None Name of each exchange on which registered The NASDAQ Stock Market LLC Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes > 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 No 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 > 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 the definitions of " large accelerated filer , " " accelerated filer , " " smaller company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . reporting Large accelerated filer Non - accelerated filer Accelerated filer Smaller reporting company Emerging growth company 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 . DOCUMENTS INCORPORATED BY REFERENCE 0 0 Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes No As of June 30 , 2020 , the aggregate market value of the voting and non - voting common equity held by non - affiliates was $ 40.7 billion based on the closing sale price as reported on the NASDAQ Global Select Market . As of February 17 , 2021 , there were 1,242,804,085 shares of common stock outstanding . Part III of this Annual Report on Form 10 - K will be incorporated by reference from certain portions of the definitive Proxy Statement for the Registrant's 2021 Annual Meeting of Stockholders , which definitive Proxy Statement will be filed with the Securities and Exchange