Sec Form 4 Filing - SCHAEFFER DAVE @ COGENT COMMUNICATIONS HOLDINGS, INC. - 2024-04-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person SCHAEFFER DAVE 2. Issuer Name and Ticker or Trading Symbol COGENT COMMUNICATIONS HOLDINGS, INC. [ CCOI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner X __ Officer (give title below) _____ Other (specify below) CHAIRMAN, CEO, AND PRESIDENT (Last) (First) (Middle) 2450 N ST NW, 4TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 04/01/2024 (Street) WASHINGTON, DC20037 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price common stock 04/01/2024 D( 1 )( 2 ) 50,165 D $ 0 4,603,038 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other SCHAEFFER DAVE 2450 N ST NW 4TH FLOOR WASHINGTON, DC20037 X X CHAIRMAN, CEO, AND PRESIDENT Signatures /s/ David Schaeffer 04/01/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On February 18, 2020, the reporting person was granted an award of 105,000 performance shares. One tranche of this award consisting of 35,000 performance shares, was dependent upon the revenue growth rate of the Company compared to the NTI between April 1, 2020 and December 31, 2023. A second tranche of this award, also consisting of 35,000 shares, was dependent upon the cash flow growth rate of the Company compared to the NTI between April 1, 2020 and December 31, 2023. ( 2 )On April 1, 2024, the Company determined that the performance criteria for the revenue growth rate goal have been partially met, resulting in the vesting of 19,835 shares of common stock and the forfeiture of 15,165 performance shares. On April 1, 2024, the Company determined that the performance criteria for the cash flow growth rate goal had not been met, resulting in a forfeiture of all 35,000 performance shares in the tranche. The aggregate forfeitures of 50,165 shares under these two tranches are reported herein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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