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( 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 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 FORM 10 - K or TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to California ( State or Other Jurisdiction of Incorporation or Orga Title of each class Common Stock , no par value Large accelerated filer Smaller reporting company □ Commission File Number : 001-09383 WESTAMERICA BANCORPORATION ( Exact name of the registrant as specified in its charter ) tion ) 1108 Fifth Avenue , San Rafael , California 94901 ( Address of principal executive offices ) ( zip code ) Registrant's telephone number , including area code : ( 707 ) 863-6000 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) WABC 94-2156203 ( I.R.S. Employer Identification Number ) 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 mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Yes No 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 if whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S T ( section 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 DOCUMENTS INCORPORATED BY REFERENCE Name of each exchange on which registered The Nasdaq Stock Market , LLC 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 . Accelerated filer Emerging growth company Non - accelerated filer 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 Common Stock held by non - affiliates of the registrant as of June 30 , 2020 as reported on the NASDAQ Global Select Market , was $ 1,546,483,328.28 . Shares of Common Stock held by each executive officer and director and by each person who owns 10 % or more of the outstanding Common Stock 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 . Number of shares outstanding of each of the registrant's classes of common stock , as of the close of business on February 18 , 2021 : 26,806,764 Shares Portions of the definitive Proxy Statement relating to registrant's Annual Meeting of Shareholders , to be held on April 22 , 2021 , are incorporated by reference in Items 10 , 11 , 12 , 13 and 14 of Part III to the extent described therein .