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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 0 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ΤΟ Delaware ( State or other jurisdiction of incorporation or organization ) For the fiscal year ended December 31 , 2020 OR 699 8th Street , Suite 600 San Francisco , California ( Address of principal executive offices ) iRhythm Technologies , Inc. ( Exact name of Registrant as specified in its Charter ) Large accelerated filer Non - accelerated filer Emerging growth company Commission File Number 001-37918 Registrant's telephone number , including area code : ( 415 ) 632-5700 Securities registered pursuant to Section 12 ( b ) of the Act : Common Stock , Par Value $ .001 Per Share , Common Stock traded on the NASDAQ stock market 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 20-8149544 ( I.R.S. Employer Identification No. ) Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 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 0 94103 ( Zip Code ) 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 and post such files ) . Yes > No Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S - K ( §229.405 ) is not contained herein , and will not be contained , to the best of Registrant's knowledge , in definitive proxy or information statements incorporated by reference in Part III of this Form 10 - K or any amendment to this Form 10 - K . 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 definition of " large accelerated filer " , " accelerated filer " , " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . ( Check one ) : Title of each class Common Stock , Par Value $ .001 Per Share Accelerated filer Small reporting company 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 . □ Indicate by check mark whether the Registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes No The aggregate market value of the voting and non - voting common equity held by non - affiliates of the Registrant , based on the closing price of the shares of common stock on The NASDAQ Stock Market on June 30 , 2020 , was approximately $ 3.1 billion . The number of shares of Registrant's Common Stock outstanding as of February 19 , 2021 was 29,160,660 . DOCUMENTS INCORPORATED BY REFERENCE : Portions of the information called for by Part III of this Form 10 - K is hereby incorporated by reference from the definitive Proxy Statements for our annual meeting of stockholders , which will be filed with the Securities and Exchange Commission not later than 120 days after December 31 , 2020 . Trading Symbol IRTC Name of each exchange on which registered The Nasdaq Stock Market