144 0001790695 XXXXXXXX LIVE 0001158324 COGENT COMMUNICATIONS HOLDINGS, INC. 000-51829 2450 N ST NW 4TH FLOOR WASHINGTON DC 20037 2022954274 Sheryl Lynn Kennedy Director common stock RBC DOMINION SECURITIES INC.

181 Bay St Suite 2200 Toronto A6 M5J 2T3

3300 53367.31 50077663 05/14/2026 NASDAQ common stock 04/01/2025 Director Compensation Issuer N 236 04/01/2025 None common stock 07/01/2025 Director Compensation Issuer N 1968 07/01/2025 None common stock 10/01/2025 Director Compensation Issuer N 1096 10/01/2025 None N RBC DOMINION SECURITIES INC.

181 Bay St Suite 2200 Toronto A6 M5J 2T3

common stock 03/05/2026 3300 75600 05/18/2026 /s/ Sheryl Lynn Kennedy