UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Quarterly Period Ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File No. 000-51829 COGENT COMMUNICATIONS HOLDINGS, INC. (Exact Name of Registrant as Specified in Its Charter) Delaware 46-5706863 (State of Incorporation) (I.R.S. Employer Identification Nu ...