COGENT COMMUNICATIONS HOLDINGS, INC.

The Board of Directors (the “Board”) of Cogent Communications Holdings, Inc. (referred to herein as the “Company,” “Cogent,” “we,” “us,” or “our”), a Delaware corporation, is soliciting your proxy on the proxy card enclosed with this Proxy Statement. Your proxy will be voted at the Annual Meeting of Stockholders (the “Annual Meeting”) to be held in person on May 1, 2026, at 9:00 a.m., Eastern Time, at the Company’s offices at 2450 N Street, NW, Washington, D.C. 20037, and any adjournment or postponement thereof. This Proxy Statement, the accompanying proxy card and the 2025 Annual Report to Stockholders are first being mailed to stockholders on or about March 20, 2026.