X0508 4 2024-09-12 0000749251 GARTNER INC IT 0001198849 HALL EUGENE A 56 TOP GALLANT ROAD P.O. BOX 10212 STAMFORD CT 06904-2212 1 1 Chairman and CEO 0 Common Stock 2024-09-12 4 S 0 4989 502.73 D 1172472 D Common Stock 2024-09-12 4 S 0 1277 503.45 D 1171195 D Common Stock 2024-09-12 4 S 0 5968 505.13 D 1165227 D Common Stock 2024-09-12 4 S 0 14030 505.75 D 1151197 D Common Stock 2024-09-12 4 S 0 7796 506.99 D 1143401 D This transaction was executed in multiple trades at prices ranging from $502.16 to $503.11. The price 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 $503.15 to $503.63. The price 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 $504.35 to $505.34. The price 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 $505.42 to $506.19. The price 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 $506.76 to $507.19. 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/ Kevin Tang for Eugene A. Hall 2024-09-16