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ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K FOR THE FISCAL YEAR ENDED DECEMBER 31 , 2020 FOR THE TRANSITION PERIOD FROM Pennsylvania ( State or other jurisdiction of incorporation or organization ) COMMISSION FILE NUMBER 001-38629 2200 Energy Drive , Canonsburg , Pennsylvania 15317 ( Address of principal executive offices ) ( Zip code ) Large Accelerated Filer Non - Accelerated Filer EQUITRANS MIDSTREAM CORPORATION ( Exact name of registrant as specified in its charter ) or Securities registered pursuant to Section 12 ( b ) of the Act Title of each class Common Stock , no par value П Registrant's telephone number , including area code : ( 724 ) 271-7600 Trading Symbol ETRN TO 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 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 X 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 Name of each exchange on which registered New York Stock Exchange Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , 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 . Accelerated Filer Smaller Reporting Company 83-0516635 ( IRS Employer Identification No. ) ☐ Emerging Growth Company 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 . 0 DOCUMENTS INCORPORATED BY REFERENCE 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 . Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes No The aggregate market value of common stock held by non - affiliates of the registrant as of June 30 , 2020 : $ 3.4 billion The number of shares of common stock outstanding ( in thousands ) , as of January 31 , 2021 : 432,470 The Company's definitive proxy statement relating to the 2021 annual meeting of shareholders will be filed with the Securities and Exchange Commission within 120 days after the close of the Company's fiscal year ended December 31 , 2020 and is incorporated by reference in Part III to the extent described therein .