Sec Form 4 Filing - MSD Partners, L.P. @ Hayward Holdings, Inc. - 2024-09-11

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 MSD Partners, L.P. 2. Issuer Name and Ticker or Trading Symbol Hayward Holdings, Inc. [ HAYW] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) X __ Other (specify below) Former 10% owner (Last) (First) (Middle) ONE VANDERBILT AVENUE, 26TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 09/11/2024 (Street) NEW YORK, NY10017 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 09/11/2024 J( 1 ) 65,003,866 D $ 0 0 I See Footnote ( 2 ) Common Stock 1,305,394 I See Footnote ( 3 ) Common Stock 1,346,472 I See Footnote ( 4 )

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 MSD Partners, L.P. ONE VANDERBILT AVENUE, 26TH FLOOR NEW YORK, NY10017 X Former 10% owner Signatures MSD PARTNERS, L.P. By: MSD Partners (GP), LLC Its: General Partner By: /s/ Robert K. Simonds Name: Robert K. Simonds Title: Authorized Signatory 09/13/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Pro rata distribution by MSD Aqua Partners, LLC ("MSD Aqua Partners") to its members for no consideration (the "Distribution"). ( 2 )MSD Aqua Partners was the record holder and direct beneficial owner of the shares of the issuer's common stock. MSD Partners, L.P. ("MSD Partners") is the manager of MSD Aqua Partners. MSD Partners (GP), LLC ("MSD GP") is the general partner of MSD Partners and may be deemed to beneficially own securities owned by MSD Partners. Gregg R. Lemkau maintains investment discretion over this investment and therefore may be deemed to beneficially own securities beneficially owned by MSD GP. Mr. Lemkau disclaims beneficial ownership of such securities except to the extent of any pecuniary interest therein. ( 3 )MSD EIV Private, LLC ("MSD EIV Private") is the record holder and direct beneficial owner of the shares of the issuer's common stock following the Distribution. MSD Partners is the manager of MSD EIV Private and may be deemed to beneficially own securities owned by MSD EIV Private. MSD GP is the general partner of MSD Partners and may be deemed to beneficially own securities owned by MSD Partners. Gregg R. Lemkau maintains investment discretion over this investment and therefore may be deemed to beneficially own securities beneficially owned by MSD GP. Mr. Lemkau disclaims beneficial ownership of such securities except to the extent of any pecuniary interest therein. ( 4 )MSD Aqua Partners, L.P. ("MSD Aqua LP") is the record holder and direct beneficial owner of the shares of the issuer's common stock following the Distribution. MSD Partners is the investment manager of MSD Aqua LP and may be deemed to beneficially own securities owned by MSD Aqua LP. MSD GP is the general partner of MSD Partners and may be deemed to beneficially own securities owned by MSD Partners. Gregg R. Lemkau maintains investment discretion over this investment and therefore may be deemed to beneficially own securities beneficially owned by MSD GP. Mr. Lemkau disclaims beneficial ownership of such securities except to the extent of any pecuniary interest therein.

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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