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( Mark One ) ☑ ☐ 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 N / A to N / A Commission file number : 0-10961 QUIDEL CORPORATION ( Exact name of registrant as specified in its charter ) Delaware ( State or other jurisdiction of incorporation or organization ) 94-2573850 ( I.R.S. Employer Identification No. ) Title of each class Common stock , $ 0.001 par value 9975 Summers Ridge Road , San Diego , California 92121 ( Address of principal executive offices , including zip code ) 858-552-1100 ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) QDEL Name of each exchange on which registered 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 ☐ 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 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 reporting company , " and " emerging growth company ” in Rule 12b - 2 of the Exchange Act . 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 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 the registrant's common stock held by non - affiliates of the registrant was $ 8,173,089,184 based on the closing sale price at which the common stock was last sold , as of the last business day of the registrant's most recently completed second fiscal quarter . As of February 5 , 2021 , 42,319,115 shares of the registrant's common stock were outstanding . DOCUMENTS INCORPORATED BY REFERENCE ( To the Extent Indicated Herein ) Portions of the registrant's definitive proxy statement to be filed with the Securities and Exchange Commission in connection with the registrant's 2021 Annual Meeting of Stockholders ( scheduled to be held on May 18 , 2021 ) are incorporated by reference into Part III , Items 10 , 11 , 12 , 13 and 14 of this Annual Report on Form 10 - K