COGENT COMMUNICATIONS HOLDINGS, INC. 10-Q

ITEM 5. OTHER INFORMATION During the three months ended June 30, 2025, no director or officer of the Company adopted or terminated a “ Rule 10b5-1 trading arrangement” or “ non -Rule 10b5-1 trading arrangement,” as each term is defined in Item 408 of Regulation S-K. ​ Page 56 of 58 Table of Contents ITEM 6. EXHIBITS . (a) Exhibits Exhibit Number Description 3.1 ​ Amended and Restated Bylaws of Cogent Communications Holdings, Inc. (as of May 7, 2025) (previously filed as Exhibit 3.1 to our Current Report on Form 8-K, filed on May 8, 2025, and incorporated herein by reference). 4.2 ​ Series 2025-1 Supplement, dated as of April 11, 2025, by and between Cogent IPv4 LLC and Wilmington Trust, National Association (previously filed as Exhibit 4.1 to our Current Report on Form 8-K, filed on April 11, 2025, and incorporated herein by reference). 4.3 ​ Second Amendment to Base Indenture, dated as of April 11, 2025, by and between Cogent IPv4 LLC and Wilmington Trust, National Association (previously filed as Exhibit 4.2 to our Current Report on Form 8-K, filed on April 11, 2025, and incorporated herein by reference).* 10.1# ​ Second Amended and Restated Cogent Communications Holdings, Inc. 2017 Incentive Award Plan (incorporated by reference to Annex B of the Company’s Definitive Proxy Statement on Schedule 14A filed March 26, 2025 (File No. 000-51829)). 31.1 ​ Certification of Chief Executive Officer (filed herewith) 31.2 ​ Certification of Chief Financial Officer (filed herewith) 32.1 ​ Certification of Chief Executive Officer (furnished herewith) 32.2 ​ Certification of Chief Financial Officer (furnished herewith) 101.1 ​ The following materials from the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2025, formatted in Inline Extensible Business Reporting Language (XBRL), include: (i) the Condensed Consolidated Statements of Comprehensive Loss, (ii) the Condensed Consolidated Balance Sheets, (iii) the Condensed Consolidated Statements of Cash Flows, and (iv) related notes (filed herewith). 104 ​ Cover Page Interactive Data File (the cover page XBRL tags are embedded within the iXBRL document). # Indicates a management contract or compensatory plan or arrangement in which directors or executive officers are eligible to participate. * In accordance with Item 601 (a) (5) of Regulation S-K, certain schedules to this exhibit have been omitted from this filing. The registrant will provide a copy of any omitted schedule to the Securities and Exchange Commission or its staff upon request. ​ ​ Page 57 of 58 Table of Contents SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. ​ ​ ​ Date: August 7, 2025 COGENT COMMUNICATIONS HOLDINGS, INC. ​ ​ ​ By: /s/ David Schaeffer ​ ​ Name: David Schaeffer ​ ​ Title: Chief Executive Officer ​ ​ ​ Date: August 7, 2025 By: /s/ Thaddeus G. Weed ​ ​ Name: Thaddeus G. Weed ​ ​ Title: Chief Financial Officer and Treasurer ​ ​ ​ ​ Page 58 of 58