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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , DC 20549 FORM 10 - K ( 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 Commission File Number : 001-39748 PubMatic , Inc. ( Exact name of registrant as specified in its charter ) Delaware ( State or other jurisdiction of incorporation or organization ) 3 Lagoon Drive , Suite 180 Redwood City , California 94065 ( 650 ) 331-3485 ( Address , including zip code , and telephone number , including area code , of registrant's principal executive offices ) 20-5863224 ( I.R.S. Employer Identification Number ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol Title of Each Class Class A common stock , $ 0.0001 par value per share PUBM Name of Each Exchange on Which Registered The Nasdaq Global Market Securities registered pursuant to Section 12 ( g ) of the Act : None Indicate by a check mark if the Registrant is a ell - known seasoned issuer , as defined in Rule 405 of Secu ies 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 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 Accelerated filer Non - 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 to Section 7 ( a ) ( 2 ) ( B ) of the Securities 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 As of June 30 , 2020 , the last business day of the registrant's most recently completed second fiscal quarter , there was no established public market for the registrant's Class A common stock , par value $ 0.0001 per share . The registrant's Class A common stock began trading on The Nasdaq Global Market on December 9 , 2020. The aggregate market value of common stock held by non - affiliates of the registrant computed by reference to the closing price of the registrant's Class A common stock on December 9 , 2020 was approximately $ 553 million . Shares of common stock held by each executive officer , director , and their affiliated holders have been excluded in that such persons may be deemed to be affiliates . This determination of affiliate status is not necessarily a conclusive determination for other purposes . As of March 15 , 2021 , there were 6,837,031 shares of the registrant's Class A common stock outstanding and 42,186,274 shares of the registrant's Class B common stock outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's proxy statement for its 2021 annual meeting of stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10 - K to the extent stated herein . Such proxy statement will be filed with the Securities and Exchange Commission within 120 days of the registrant's fiscal year ended December