X0306 4 2018-05-15 0 0001262039 FORTINET INC FTNT 0001418649 Jensen Keith C/O FORTINET, INC. 899 KIFER ROAD SUNNYVALE CA 94086 0 1 0 0 CFO & Chief Accounting Officer Common Stock 2018-05-15 4 S 0 2600 59.1638 D 762 D Common Stock 2018-05-15 4 S 0 200 59.54 D 562 D Common Stock 2018-05-16 4 M 0 208 23.83 A 770 D Common Stock 2018-05-16 4 M 0 416 37.24 A 1186 D Common Stock 2018-05-16 4 S 0 624 59.44 D 562 D Non-qualified Stock Option (right to buy) 23.83 2018-05-16 4 M 0 208 0 D 2023-02-11 Common Stock 208 4376 D Non-qualified Stock Option (right to buy) 37.24 2018-05-16 4 M 0 416 0 D 2024-02-16 Common Stock 416 13751 D The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 1, 2018. Represents the aggregate of sales effected on the same day at different prices. Represents the weighted average sales price per share. The shares sold at prices ranging from $58.44 to $59.43 per share. Full information regarding the number of shares sold at each price shall be provided upon request to the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer. Represents the weighted average sales price per share. The shares sold at prices ranging from $59.52 to $59.56 per share. Full information regarding the number of shares sold at each price shall be provided upon request to the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer. 1/4 of the shares subject to the option vested on February 11, 2017 and 1/48 of the shares subject to the option vest monthly thereafter. 1/4 of the shares subject to the option vested on February 16, 2018 and 1/48 of the shares subject to the option vest monthly thereafter. /s/ John Whittle, by power of attorney 2018-05-16