X0306 4 2022-05-10 0001100682 CHARLES RIVER LABORATORIES INTERNATIONAL, INC. CRL 0001221496 MASSARO GEORGE 251 BALLARDVALE STREET WILMINGTON MA 01887 1 Common Stock 2022-05-09 4 S 0 24 228.62 D 4831 D Common Stock 2022-05-09 4 S 0 88 229.8972 D 4743 D Common Stock 2022-05-09 4 S 0 15 230.33 D 4728 D Common Stock 2022-05-09 4 S 0 15 231.88 D 4713 D Common Stock 2022-05-09 4 S 0 13 232.79 D 4700 D Common Stock 2022-05-09 4 S 0 15 235.23 D 4685 D Common Stock 2022-05-09 4 S 0 8 238.06 D 4677 D This sale occurred pursuant to a 10b5-1 Trading Plan. This transaction was executed in multiple trades at prices ranging from $228.22 to $228.62. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $229.43 to $230.045. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. /s/ George E. Massaro 2022-05-11