Sec Form 4 Filing - MSD Partners, L.P. @ Hayward Holdings, Inc. - 2021-04-13

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 X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 645 FIFTH AVENUE, 21ST FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 04/13/2021 (Street) NEW YORK, NY10022 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 Stock 04/13/2021 S 1,120,044 D $ 16.065 ( 1 ) 71,538,085 I See Footnotes ( 2 ) ( 3 ) ( 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. 645 FIFTH AVENUE, 21ST FLOOR NEW YORK, NY10022 X X MSD Aqua Partners, LLC 645 FIFTH AVENUE, 21ST FLOOR NEW YORK, NY10022 X X Signatures MSD PARTNERS, L.P. By: MSD Partners (GP), LLC Its: General Partner By: /s/ Marc R. Lisker Name: Marc R. Lisker Title: Manager 04/14/2021 Signature of Reporting Person Date MSD AQUA PARTNERS, LLC By: MSD Partners, L.P. Its: Manager By: MSD Partners (GP), LLC Its: General Partner By: /s/ Marc R. Lisker Name: Marc R. Lisker Title: Manager 04/14/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents price net of underwriting discounts. ( 2 )This statement is jointly filed by and on behalf of each of MSD Partners, L.P. ("MSD Partners") and MSD Aqua Partners, LLC ("MSD Aqua Partners"). MSD Aqua Partners is the record and direct beneficial owner of the shares of the issuer's common stock reported herein. MSD Partners is the manager of MSD Aqua Partners and may be deemed to beneficially own securities owned by MSD Aqua Partners. MSD Partners (GP), LLC ("MSD GP", and together with MSD Partners and MSD Aqua Partners, the "MSD Parties") is the general partner of MSD Partners and may be deemed to beneficially own securities owned by MSD Partners. Each of John Phelan, Marc R. Lisker and Brendan Rogers is a manager of MSD GP and may be deemed to beneficially own securities owned by MSD GP. Each of Messrs. Phelan, Lisker and Rogers disclaims beneficial ownership of such securities except to the extent of any pecuniary interest therein ( 3 )In connection with the consummation of the initial public offering of the issuer's common stock, MSD Aqua Partners will enter into an Amended and Restated Stockholders' Agreement ("Stockholders' Agreement") with the issuer and certain affiliates of CCMP Capital Advisors, LP ("CCMP") and Alberta Investment Management Corporation ("AIMCo") pursuant to which MSD Aqua Partners and CCMP have agreed to coordinate with respect to the with respect to the timing and manner of disposition of shares of the issuer's common stock held by them, and AIMCo has also agreed to certain restrictions on the transfer of its shares of common stock. [cont.] ( 4 )By virtue of the Stockholders' Agreement, the MSD Parties, CCMP and AIMCo may be deemed to be members of a group for the purposes of Section 13(d) of the Securities Exchange Act of 1934 (the "Act"). In addition, each reporting person and each of Messrs. Phelan, Lisker and Rogers may be deemed to be a member of a group for the purposes of Section 13(d) of the Act. Each reporting person and each of Messrs. Phelan, Lisker and Rogers disclaims any pecuniary interest in any shares of the issuer's common stock held by the group with CCMP and AIMCo except as reported in this Form 4.

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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