SCHEDULE 13G/A 0001620062 XXXXXXXX LIVE 3 Common Stock 03/31/2025 0001833197 Latham Group, Inc. 51819L107 787 Watervliet Shaker Road Latham NY 12110 Rule 13d-1(d) WYNNCHURCH CAPITAL PARTNERS IV, L.P. b E9 0 11050953 0 11050953 11050953 N 9.5 PN The 11,050,953 shares of Common Stock reported above are held directly by Wynnchurch Capital Partners IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes, Christopher P. O'Brien and Gregory B. Gleason. Wynnchurch Capital Partners IV, L.P. ("Wynnchurch IV") and WC Partners Executive IV, L.P. ("WC Executive") have agreed that until the date, if any, that they and their affiliates own more than 50% of the Common Stock, Wynnchurch IV and WC Executive will not vote, and will cause each of their affiliates not to vote, any shares of Common Stock that represent more than 9.9% of the outstanding Common Stock. WC PARTNERS EXECUTIVE IV, L.P. b 0 332818 0 332818 332818 N 0.3 PN The 332,818 shares of Common Stock reported above are held directly by WC Partners Executive IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of WC Partners Executive IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to WC Partners Executive IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes and Christopher P. O'Brien. Wynnchurch Capital Partners IV, L.P. ("Wynnchurch IV") and WC Partners Executive IV, L.P. ("WC Executive") have agreed that until the date, if any, that they and their affiliates own more than 50% of the Common Stock, Wynnchurch IV and WC Executive will not vote, and will cause each of their affiliates not to vote, any shares of Common Stock that represent more than 9.9% of the outstanding Common Stock. Wynnchurch Partners IV, L.P. b E9 0 11383771 0 11383771 11383771 N 9.8 PN The 11,383,711 shares of Common Stock reported above are held directly by WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes, Christopher P. O'Brien and Gregory B. Gleason. Wynnchurch Capital, L.P. b DE 0 11383771 0 11383771 11383771 N 9.8 PN The 11,383,711 shares of Common Stock reported above are held directly by WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes, Christopher P. O'Brien and Gregory B. Gleason. John A. Hatherly b X1 0 11383771 0 11383771 11383771 N 9.8 IN The 11,383,711 shares of Common Stock reported above are held directly by WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes, Christopher P. O'Brien and Gregory B. Gleason. Francis G. Hayes b X1 0 11383771 0 11383771 11383771 N 9.8 IN The 11,383,711 shares of Common Stock reported above are held directly by WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes, Christopher P. O'Brien and Gregory B. Gleason. Christopher Patrick OBrien b X1 0 11383771 0 11383771 11383771 N 9.8 IN The 11,383,711 shares of Common Stock reported above are held directly by WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes, Christopher P. O'Brien and Gregory B. Gleason. Gregory B. Gleason b X1 0 11383771 0 11383771 11383771 N 9.8 IN The 11,383,711 shares of Common Stock reported above are held directly by WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to WC Partners Executive IV, L.P. and Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes, Christopher P. O'Brien and Gregorgy B. Gleason. Latham Group, Inc. 787 Watervliet Shaker Road, Latham, New York, 12110 The persons filing this Schedule 13G are (the "Reporting Persons"): Wynnchurch Partners IV, L.P.; Wynnchurch Capital, L.P.; WC Partners Executive IV, L.P.; Wynnchurch Capital Partners IV, L.P.: John A. Hatherly; Francis G. Hayes; Christopher Patrick O'Brien; and Gregory B. Gleason. The business address of the Reporting Persons is 6250 N. River Road, Suite 10-100, Rosemont, IL 60018. Wynnchurch Partners IV, L.P., WC Partners Executive IV, L.P., Wynnchurch Capital Partners IV, L.P. are Cayman Islands partnerships. Wynnchurch Capital, L.P. is a Delaware partnership. John A. Hatherly, Francis G. Hayes, Christopher Patrick O'Brien and Gregory B. Gleason are United States citizens. Y The information required by Items 4(a) - (c) is set forth in Rows 5 through 11 of the cover page for each Reporting Person and incorporated herein by reference for each such Reporting Person. The aggregate 11,050,953 shares of Common Stock reported herein are held directly by Wynnchurch Capital Partners IV, L.P. Wynnchurch Partners IV, L.P. is the general partner of Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is the investment adviser to Wynnchurch Capital Partners IV, L.P. Wynnchurch Capital, L.P. is principally owned and controlled by John A. Hatherly, Francis G. Hayes, Christopher P. O'Brien and Gregory B. Gleason. Wynnchurch Capital Partners IV, L.P. ("Wynnchurch IV") and WC Partners Executive IV, L.P. ("WC Executive") have agreed that until the date, if any, that they and their affiliates own more than 50% of the Common Stock, Wynnchurch IV and WC Executive will not vote, and will cause each of their affiliates not to vote, any shares of Common Stock that represent more than 9.9% of the outstanding Common Stock. The information required by Items 4(a) - (c) is set forth in Rows 5 through 11 of the cover page for each Reporting Person and incorporated herein by reference for each such Reporting Person. The information required by Items 4(a) - (c) is set forth in Rows 5 through 11 of the cover page for each Reporting Person and incorporated herein by reference for each such Reporting Person. The information required by Items 4(a) - (c) is set forth in Rows 5 through 11 of the cover page for each Reporting Person and incorporated herein by reference for each such Reporting Person. The information required by Items 4(a) - (c) is set forth in Rows 5 through 11 of the cover page for each Reporting Person and incorporated herein by reference for each such Reporting Person. The information required by Items 4(a) - (c) is set forth in Rows 5 through 11 of the cover page for each Reporting Person and incorporated herein by reference for each such Reporting Person. Y Y Y N Pamplona Capital Partners V, L. P. (the "Pamplona Fund") entered into a stockholders agreement, dated as April 27, 2021 (the "Stockholders Agreement"), with Wynnchurch Capital Partners IV, L.P. and WC Partners Executive IV, L.P. (collectively, the "Wynnchurch Funds"). Pursuant to the Stockholders Agreement, each of the Pamplona Fund and the Wynnchurch Funds have agreed, among other things, to vote their shares of Common Stock to elect members of the board of directors of the Issuer as set forth therein. Because of the relationship between the Pamplona Fund and the Wynnchurch Funds as a result of the Stockholders Agreement, the Reporting Persons may be deemed, pursuant to Rule 13d-3 under the Act, to beneficially own the shares of Common Stock beneficially owned by the Wynnchurch Funds and/or to constitute a "group" with the Wynnchurch Funds. Each Reporting Person disclaims beneficial ownership of the shares of Common Stock beneficially owned by the Pamplona Fund. Y Y Exhibit 99.1 Joint Filing Agreement WYNNCHURCH CAPITAL PARTNERS IV, L.P. /s/ Christopher P. O'Brien 05/14/2025 WC PARTNERS EXECUTIVE IV, L.P. /s/ Christopher P. O'Brien 05/14/2025 Wynnchurch Partners IV, L.P. /s/ Christopher P. O'Brien 05/14/2025 Wynnchurch Capital, L.P. /s/ Christopher P. O'Brien 05/14/2025 John A. Hatherly /s/ John A. Hatherly 05/14/2025 Francis G. Hayes /s/ Francis G. Hayes 05/14/2025 Christopher Patrick OBrien /s/ Christopher Patrick O'Brien 05/14/2025 Gregory B. Gleason /s/ Gregory B. Gleason 05/14/2025