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( Mark One ) 冈 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM Delaware ( State or Other Jurisdiction of Incorporation or Organization ) 251 Ballardvale Street FOR THE FISCAL YEAR ENDED December 26 , 2020 FORM 10 - K charles river CHARLES RIVER LABORATORIES INTERNATIONAL , INC . ( Exact Name of Registrant as Specified in Its Charter ) Title of each class Common stock , $ 0.01 par value Commission File No. 001-15943 ( Address of Principal Executive Offices ) Wilmington ΤΟ Massachusetts Large accelerated filer Non - accelerated filer ( Registrant's telephone number , including area code ) : ( 781 ) 222-6000 Securities registered pursuant to Section 12 ( b ) of the Act : Ticker symbol ( s ) CRL 06-1397316 ✓ ( I.R.S. Employer Identification No. ) 01887 ( Zip Code ) Securities registered pursuant to Section 12 ( g ) of the Act : Yes No Indicate by check mark whether 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 Name of each exchange on which registered New York Stock Exchange 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 the definitions of " large accelerated filer , " " accelerated filer " , " smaller reporting company ” , " emerging growth company " in Rule 12b - 2 of the Exchange Act . Accelerated filer Smaller reporting company Emerging growth company and