Sec Form 4 Filing - Apollo Principal Holdings VI, L.P. @ Diameter Credit Co - 2024-03-11

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 Apollo Principal Holdings VI, L.P. 2. Issuer Name and Ticker or Trading Symbol Diameter Credit Co [ NONE] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 9 W. 57TH STREET, 41ST FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 03/11/2024 (Street) NEW YORK, NY10019 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 shares of beneficial interest 03/11/2024 P( 1 ) 258,305.59 A $ 25.5511 1,202,305.59 I See Footnote ( 2 )

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 Apollo Principal Holdings VI, L.P. 9 W. 57TH STREET, 41ST FLOOR NEW YORK, NY10019 X Apollo Principal Holdings VI GP, LLC 9 W. 57TH STREET, 41ST FLOOR NEW YORK, NY10019 X AP DLF Offshore Investor, LP 9 W. 57TH STREET, 41ST FLOOR NEW YORK, NY10019 X APO Corp. 9 W. 57TH STREET, 41ST FLOOR NEW YORK, NY10019 X Signatures see signatures attached as Exhibit 99.2 03/13/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On February 26, 2024, Diameter Credit Co, a Delaware corporation (the "Issuer"), issued a capital call notice to certain investors that have committed to purchase shares of common shares of beneficial interest of the Issuer ("Common Shares"). Pursuant to such capital call notice, AP DLF Offshore Investor, L.P. ("Offshore Investor") was obligated to make a capital contribution of $6,600,000.00 on March 11, 2024, and the Issuer issued 258,305.59 Common Shares to Offshore Investor on such date. ( 2 )Offshore Investor holds securities of the Issuer. Apollo Principal Holdings VI, L.P. ("Principal Holdings VI") serves as the general partner of Offshore Investor. The general partner of Principal Holdings VI is Apollo Principal Holdings VI GP, LLC ("Principal Holdings VI GP"). APO Corp. is the sole member of Principal Holdings VI GP.

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).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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