X0306 4 2021-08-23 0 0001262039 Fortinet, Inc. FTNT 0001476336 Whittle John C/O FORTINET, INC. 899 KIFER ROAD SUNNYVALE CA 94086 0 1 0 0 VP Corp Dev&Strat Alliance,GC Common Stock 2021-08-23 4 M 0 1216 49.06 A 1216 D Common Stock 2021-08-23 4 M 0 700 84.49 A 1916 D Common Stock 2021-08-23 4 M 0 496 114.48 A 2412 D Common Stock 2021-08-23 4 S 0 100 301.94 D 2312 D Common Stock 2021-08-23 4 S 0 500 303.886 D 1812 D Common Stock 2021-08-23 4 S 0 400 304.85 D 1412 D Common Stock 2021-08-23 4 S 0 700 306.2657 D 712 D Common Stock 2021-08-23 4 S 0 612 307.4033 D 100 D Common Stock 2021-08-23 4 S 0 100 308.23 D 0 D Stock Option (right to buy) 49.06 2021-08-23 4 M 0 1216 0.00 D 2025-02-20 Common Stock 1216 27959 D Stock Option (right to buy) 84.49 2021-08-23 4 M 0 700 0.00 D 2026-02-21 Common Stock 700 12598 D Stock Option (right to buy) 114.48 2021-08-23 4 M 0 496 0.00 D 2027-02-21 Common Stock 496 14873 D The reported transaction was effected pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person. Represents the weighted average sale price. The lowest price at which shares were sold was $303.49 and the highest price at which shares were sold was $304.19. The Reporting Person undertakes to provide upon request to the staff of the Securities and Exchange Commission, the Issuer or its stockholders, full information regarding the total number of shares sold at each separate price within the ranges set forth in footnotes (2) through (5) to this Form 4. Represents the weighted average sale price. The lowest price at which shares were sold was $304.65 and the highest price at which shares were sold was $305.19. Represents the weighted average sale price. The lowest price at which shares were sold was $305.72 and the highest price at which shares were sold was $306.54. Represents the weighted average sale price. The lowest price at which shares were sold was $306.77 and the highest price at which shares were sold was $307.76. 1/4 of the shares subject to the option vested on February 20, 2019 and 1/48 of the shares subject to the option will vest monthly thereafter, subject to the Reporting Person's provision of service to the Issuer on each vesting date. 1/4 of the shares subject to the option vested on February 21, 2020 and 1/48 of the shares subject to the option will vest monthly thereafter, subject to the Reporting Person's provision of service to the Issuer on each vesting date. 1/4 of the shares subject to the option will vest on February 21, 2021 and 1/48 of the shares subject to the option will vest monthly thereafter, subject to the Reporting Person's provision of service to the Issuer on each vesting date. /s/ Robert Turner, by power of attorney 2021-08-24