X0306 4 2022-11-07 0 0000874716 IDEXX LABORATORIES INC /DE IDXX 0001556270 MAZELSKY JONATHAN JAY ONE IDEXX DRIVE WESTBROOK ME 04092 1 1 0 0 President & CEO Common Stock 2022-11-07 4 M 0 24002 52 A 75536.6426 D Common Stock 2022-11-07 4 S 0 900 378.5951 D 74636.6426 D Common Stock 2022-11-07 4 S 0 2000 379.4994 D 72636.6426 D Common Stock 2022-11-07 4 S 0 500 380.8520 D 72136.6426 D Common Stock 2022-11-07 4 S 0 3704 382.8057 D 68432.6426 D Common Stock 2022-11-07 4 S 0 2716 383.2864 D 65716.6426 D Common Stock 2022-11-07 4 S 0 3018 384.4651 D 62698.6426 D Common Stock 2022-11-07 4 S 0 392 385.0122 D 62306.6426 D Non-Qualified Stock Option (right-to-buy) 52 2022-11-07 4 M 0 24002 D 2023-12-04 Common Stock 24002 0 D Includes 17 shares acquired under the IDEXX Laboratories, Inc. Employee Stock Purchase Plan on September 30, 2022 Represents the weighted average price of the shares sold ranging from a low of $377.99 to a high of $378.95 per share. The undersigned undertakes, upon request by the Commission staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares purchased at each separate price. Represents the weighted average price of the shares sold ranging from a low of $379.10 to a high of $380.06 per share. The undersigned undertakes, upon request by the Commission staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares purchased at each separate price. Represents the weighted average price of the shares sold ranging from a low of $380.68 to a high of $381.04 per share. The undersigned undertakes, upon request by the Commission staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares purchased at each separate price. Represents the weighted average price of the shares sold ranging from a low of $381.94 to a high of $382.94 per share. The undersigned undertakes, upon request by the Commission staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares purchased at each separate price. Represents the weighted average price of the shares sold ranging from a low of $382.95 to a high of $383.95 per share. The undersigned undertakes, upon request by the Commission staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares purchased at each separate price. Represents the weighted average price of the shares sold ranging from a low of $383.97 to a high of $384.935 per share. The undersigned undertakes, upon request by the Commission staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares purchased at each separate price. Represents the weighted average price of the shares sold ranging from a low of $384.98 to a high of $385.16 per share. The undersigned undertakes, upon request by the Commission staff, the issuer or a security holder of the issuer, to provide full information regarding the number of shares purchased at each separate price. Grant of option to buy 24,501 shares of Issuer common stock that became exercisable in five annual installments beginning December 5, 2014 without giving effect to the 2-for-1 stock split of IDEXX Laboratories, Inc. common stock that occurred on June 15, 2015 (the "Stock Split"). The number of derivative securities reported as beneficially owned with respect to this option and its exercise price were adjusted to reflect the Stock Split. Not applicable. /s/ Lily J. Lu, Attorney-in-Fact for Jonathan Jay Mazelsky 2022-11-09