X0202 SCHEDULE 13G 0001103804 XXXXXXXX LIVE Common Stock, $0.01 par value per share 04/15/2026 0001069202 LENNOX INTERNATIONAL INC 526107107 2140 Lake Park Blvd. Richardson TX 75080 Rule 13d-1(c) VIKING GLOBAL INVESTORS LP b DE 0 1815350 0 1815350 1815350 N 5.2 PN See Item 4 VIKING GLOBAL PERFORMANCE LLC b DE 0 1174224 0 1174224 1174224 N 3.4 OO See Item 4 Viking Global Equities II LP b DE 0 23495 0 23495 23495 N 0.1 PN See Item 4 Viking Global Equities Master Ltd. b E9 0 1150729 0 1150729 1150729 N 3.3 CO See Item 4 Viking Long Fund GP LLC b DE 0 434463 0 434463 434463 N 1.2 OO See Item 4 Viking Long Fund Master Ltd. b E9 0 434463 0 434463 434463 N 1.2 CO See Item 4 Viking Global Opportunities Parent GP LLC b DE 0 206663 0 206663 206663 N 0.6 OO See Item 4 Viking Global Opportunities GP LLC b DE 0 206663 0 206663 206663 N 0.6 OO See Item 4 Viking Global Opportunities Portfolio GP LLC b DE 0 206663 0 206663 206663 N 0.6 OO See Item 4 Viking Global Opportunities Liquid Portfolio Sub-Master LP b E9 0 206663 0 206663 206663 N 0.6 PN See Item 4 HALVORSEN OLE ANDREAS b Q8 0 1815350 0 1815350 1815350 N 5.2 IN See Item 4 Shabet Rose Sharon b X1 0 1815350 0 1815350 1815350 N 5.2 IN See Item 4 LENNOX INTERNATIONAL INC 2140 Lake Park Blvd., Richardson, Texas 75080 Viking Global Investors LP ("VGI"), Viking Global Performance LLC ("VGP"), Viking Global Equities II LP ("VGEII"), Viking Global Equities Master Ltd. ("VGEM"), Viking Long Fund GP LLC ("VLFGP"), Viking Long Fund Master Ltd. ("VLFM"), Viking Global Opportunities Parent GP LLC ("Opportunities Parent"), Viking Global Opportunities GP LLC ("Opportunities GP"), Viking Global Opportunities Portfolio GP LLC ("Opportunities Portfolio GP"), Viking Global Opportunities Liquid Portfolio Sub-Master LP ("VGOL"), O. Andreas Halvorsen and Rose S. Shabet (collectively, the "Reporting Persons") The business address of each of the Reporting Persons is: 600 Washington Boulevard, Floor 11, Stamford, Connecticut 06901. VGI and VGEII are Delaware limited partnerships; VGP, VLFGP, Opportunities Parent, Opportunities GP and Opportunities Portfolio GP are Delaware limited liability companies; VGEM and VLFM are Cayman Islands exempted companies; VGOL is a Cayman Islands exempted limited partnership; O. Andreas Halvorsen is a citizen of Norway; and Rose S. Shabet is a citizen of the United States. Y VGI: 1,815,350 VGI provides managerial services to VGEII, VGEM, VLFM and VGOL. VGI has the authority to dispose of and vote the shares of Common Stock directly owned by VGEII, VGEM, VLFM and VGOL. VGI does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Act"), VGI may be deemed to beneficially own the shares of Common Stock directly held by VGEII, VGEM, VLFM and VGOL. VGP: 1,174,224 VGP, as the general partner of VGEII, has the authority to dispose of and vote the shares of Common Stock directly owned by VGEII. VGP serves as investment manager to VGEM and has the authority to dispose of and vote the shares of Common Stock directly owned by VGEM. VGP does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Act, VGP may be deemed to beneficially own the shares of Common Stock directly held by VGEII and VGEM. VGEII: 23,495 VGEII has the authority to dispose of and vote the shares of Common Stock directly owned by it, which power may be exercised by its general partner, VGP, and by VGI, an affiliate of VGP, which provides managerial services to VGEII. VGEM: 1,150,729 VGEM has the authority to dispose of and vote the shares of Common Stock directly owned by it, which power may be exercised by its investment manager, VGP, and by VGI, an affiliate of VGP, which provides managerial services to VGEM. Viking Global Equities LP (a Delaware limited partnership) and Viking Global Equities III Ltd. (a Cayman Islands exempted company), through its investment in VGE III Portfolio Ltd. (a Cayman Islands exempted company), invest substantially all of their assets through VGEM. VLFGP: 434,463 VLFGP serves as the investment manager of VLFM and has the authority to dispose of and vote the shares of Common Stock directly owned by VLFM. VLFGP does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Act, VLFGP may be deemed to beneficially own the shares of Common Stock directly held by VLFM. VLFM: 434,463 VLFM has the authority to dispose of and vote the shares of Common Stock directly owned by it, which power may be exercised by its investment manager, VLFGP, and by VGI, an affiliate of VLFGP, which provides managerial services to VLFM. Viking Long Fund LP (a Delaware limited partnership) and Viking Long Fund III Ltd. (a Cayman Islands exempted company), through its investment in Viking Long Fund Intermediate L.P. (a Cayman Islands limited partnership), invest substantially all of their assets through VLFM. Opportunities Parent: 206,663 Opportunities Parent is the sole member of Opportunities GP, which has the authority to dispose of and vote the shares of Common Stock controlled by Opportunities Portfolio GP, which consists of the shares of Common Stock directly held by VGOL. Opportunities Parent does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Act, Opportunities Parent may be deemed to beneficially own the shares of Common Stock directly held by VGOL. Opportunities GP: 206,663 Opportunities GP serves as the sole member of Opportunities Portfolio GP and has the authority to dispose of and vote the shares of Common Stock controlled by Opportunities Portfolio GP, which consists of the shares of Common Stock directly held by VGOL. Opportunities GP does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Act, Opportunities GP may be deemed to beneficially own the shares of Common Stock directly held by VGOL. Opportunities Portfolio GP: 206,663 Opportunities Portfolio GP serves as the general partner of VGOL and has the authority to dispose of and vote the shares of Common Stock directly owned by VGOL. Opportunities Portfolio GP does not directly own any shares of Common Stock. Based on Rule 13d-3 under the Act, Opportunities Portfolio GP may be deemed to beneficially own the shares of Common Stock directly held by VGOL. VGOL: 206,663 VGOL has the authority to dispose of and vote the shares of Common Stock directly owned by it, which power may be exercised by its general partner, Opportunities Portfolio GP, and by VGI, an affiliate of Opportunities Portfolio GP, which provides managerial services to VGOL. Viking Global Opportunities LP (a Delaware limited partnership) and Viking Global Opportunities III LP (a Cayman Islands exempted limited partnership), through its investment in Viking Global Opportunities Intermediate LP (a Cayman Islands exempted limited partnership), invest substantially all of their assets in Viking Global Opportunities Master LP (a Cayman Islands exempted limited partnership), which in turn invests through VGOL. O. Andreas Halvorsen and Rose S. Shabet: 1,815,350 Mr. Halvorsen and Ms. Shabet, as Executive Committee Members of Viking Global Partners LLC (general partner of VGI), VGP, VLFGP and Opportunities Parent, have shared authority to dispose of and vote the shares of Common Stock beneficially owned by VGI, VGP, VLFGP and Opportunities Parent. Neither Mr. Halvorsen nor Ms. Shabet directly owns any shares of Common Stock. Based on Rule 13d-3 under the Act, each may be deemed to beneficially own the shares of Common Stock directly held by VGEII, VGEM, VLFM and VGOL. Mr. Halvorsen and Ms. Shabet each beneficially own 1,815,350 shares of Common Stock consisting of (i) 23,495 shares of Common Stock directly and beneficially owned by VGEII, (ii) 1,150,729 shares of Common Stock directly and beneficially owned by VGEM, (iii) 434,463 shares of Common Stock directly and beneficially owned by VLFM and (iv) 206,663 shares of Common Stock directly and beneficially owned by VGOL. The percentages set forth herein are based on 34,817,885 shares of Common Stock outstanding as of March 26, 2026, as reported by the Issuer in its proxy statement on Schedule 14A, filed with the U.S. Securities and Exchange Commission (the "Commission") on April 8, 2026. VGI: 5.2% VGP: 3.4% VGEII: 0.1% VGEM: 3.3% VLFGP: 1.2% VLFM: 1.2% Opportunities Parent: 0.6% Opportunities GP: 0.6% Opportunities Portfolio GP: 0.6% VGOL: 0.6% O. Andreas Halvorsen and Rose S. Shabet: 5.2% VGI: 0 VGP: 0 VGEII: 0 VGEM: 0 VLFGP: 0 VLFM: 0 Opportunities Parent: 0 Opportunities GP: 0 Opportunities Portfolio GP: 0 VGOL: 0 O. Andreas Halvorsen and Rose S. Shabet: 0 VGI: 1,815,350 VGP: 1,174,224 VGEII: 23,495 VGEM: 1,150,729 VLFGP: 434,463 VLFM: 434,463 Opportunities Parent: 206,663 Opportunities GP: 206,663 Opportunities Portfolio GP: 206,663 VGOL: 206,663 O. Andreas Halvorsen and Rose S. Shabet: 1,815,350 VGI: 0 VGP: 0 VGEII: 0 VGEM: 0 VLFGP: 0 VLFM: 0 Opportunities Parent: 0 Opportunities GP: 0 Opportunities Portfolio GP: 0 VGOL: 0 O. Andreas Halvorsen and Rose S. Shabet: 0 VGI: 1,815,350 VGP: 1,174,224 VGEII: 23,495 VGEM: 1,150,729 VLFGP: 434,463 VLFM: 434,463 Opportunities Parent: 206,663 Opportunities GP: 206,663 Opportunities Portfolio GP: 206,663 VGOL: 206,663 O. Andreas Halvorsen and Rose S. Shabet: 1,815,350 Y N The response to Item 4 is incorporated by reference herein. Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. EXHIBIT A - JOINT FILING AGREEMENT VIKING GLOBAL INVESTORS LP /s/ Scott M. Hendler 04/22/2026 VIKING GLOBAL PERFORMANCE LLC /s/ Scott M. Hendler 04/22/2026 Viking Global Equities II LP /s/ Scott M. Hendler 04/22/2026 Viking Global Equities Master Ltd. /s/ Scott M. Hendler 04/22/2026 Viking Long Fund GP LLC /s/ Scott M. Hendler 04/22/2026 Viking Long Fund Master Ltd. /s/ Scott M. Hendler 04/22/2026 Viking Global Opportunities Parent GP LLC /s/ Scott M. Hendler 04/22/2026 Viking Global Opportunities GP LLC /s/ Scott M. Hendler 04/22/2026 Viking Global Opportunities Portfolio GP LLC /s/ Scott M. Hendler 04/22/2026 Viking Global Opportunities Liquid Portfolio Sub-Master LP /s/ Scott M. Hendler 04/22/2026 HALVORSEN OLE ANDREAS /s/ Scott M. Hendler 04/22/2026 Shabet Rose Sharon /s/ Scott M. Hendler 04/22/2026 (1) Scott M. Hendler is signing on behalf of O. Andreas Halvorsen, individually and as an Executive Committee Member of VIKING GLOBAL PARTNERS LLC, on behalf of VIKING GLOBAL INVESTORS LP, and as an Executive Committee Member of VIKING GLOBAL PERFORMANCE LLC, on behalf of itself and VIKING GLOBAL EQUITIES II LP and VIKING GLOBAL EQUITIES MASTER LTD., and as an Executive Committee Member of VIKING LONG FUND GP LLC, on behalf of itself and VIKING LONG FUND MASTER LTD., and as an Executive Committee Member of VIKING GLOBAL OPPORTUNITIES PARENT GP LLC, on behalf of itself and VIKING GLOBAL OPPORTUNITIES GP LLC, VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC, and VIKING GLOBAL OPPORTUNITIES LIQUID PORTFOLIO SUB-MASTER LP, pursuant to an authorization and designation letter dated February 9, 2021, which was previously filed with the Commission as an exhibit to a Form 13G filed by Mr. Halvorsen on February 12, 2021 (SEC File No. 005-49737). (2) Scott M. Hendler is signing on behalf of Rose S. Shabet, individually and as an Executive Committee Member of VIKING GLOBAL PARTNERS LLC, on behalf of VIKING GLOBAL INVESTORS LP, and as an Executive Committee Member of VIKING GLOBAL PERFORMANCE LLC, on behalf of itself and VIKING GLOBAL EQUITIES II LP and VIKING GLOBAL EQUITIES MASTER LTD., and as an Executive Committee Member of VIKING LONG FUND GP LLC, on behalf of itself and VIKING LONG FUND MASTER LTD., and as an Executive Committee Member of VIKING GLOBAL OPPORTUNITIES PARENT GP LLC, on behalf of itself and VIKING GLOBAL OPPORTUNITIES GP LLC, VIKING GLOBAL OPPORTUNITIES PORTFOLIO GP LLC, and VIKING GLOBAL OPPORTUNITIES LIQUID PORTFOLIO SUB-MASTER LP, pursuant to an authorization and designation letter dated February 9, 2021, which was previously filed with the Commission as an exhibit to a Form 13G filed by Ms. Shabet on February 12, 2021 (SEC File No. 005-49737).