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冈 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 001-36189 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 Delaware ( State or other jurisdiction of incorporation or organization ) 11075 Roselle Street San Diego California ( Address of principal executive offices ) FORM 10 - K Tandem Diabetes Care , Inc. ( Exact name of registrant as specified in its charter ) Title of Each Class Common Stock , par value $ 0.001 per share Large accelerated filer Non - accelerated filer X ( 858 ) 366-6900 Registrant's telephone number , including area code Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) . 20-4327508 ( I.R.S. Employer Identification No. ) 92121 ( Zip Code ) TNDM 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 Indicate by check 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 Name of Each Exchange on Which Registered Nasdaq Global Market 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 emerging growth company . See definitions of " large accelerated filer , " accelerated filer , " " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . NO □ No 区 Accelerated filer Smaller reporting company Emerging growth company 000 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 Act ) . Yes No > As of June 30 , 2020 , the aggregate market value of the registrant's common stock held by non - affiliates was approximately $ 5.8 billion based on the closing price for the common stock of $ 98.92 on that date . Shares of common stock held by each executive officer , director , and their affiliated stockholders have been excluded from this calculation as such persons may be deemed to be affiliates . This determination of affiliate status is not necessarily a conclusive determination for other purposes . As of February 19 , 2021 , there were 62,504,754 shares of the registrant's common stock outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's definitive Proxy Statement for the 2021 Annual Meeting of Stockholders , to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Form 10 - K , are incorporated by reference in Part III , Items 10-14 of this Form 10 - K . Except for the portions of the Proxy Statement specifically incorporated by reference in this Form 10 - K , the Proxy Statement shall not be deemed to be filed as part hereof .