SCHEDULE 13G/A 0001315863-25-000393 0001565854 XXXXXXXX LIVE 1 Common Stock, par value $0.01 per share 06/30/2025 0001743907 Sun Country Airlines Holdings, Inc. 866683105 2005 CARGO ROAD MINNEAPOLIS MN 55450 Rule 13d-1(b) Zimmer Partners, LP DE 0 2225900 0 2225900 2225900 N 4.2 IN HC Zimmer Financial Services Group LLC DE 0 2225900 0 2225900 2225900 N 4.2 OO HC Zimmer Partners GP, LLC DE 0 2225900 0 2225900 2225900 N 4.2 OO HC Stuart J. Zimmer X1 0 2225900 0 2225900 2225900 N 4.2 IN HC Sun Country Airlines Holdings, Inc. 2005 CARGO ROAD, MINNEAPOLIS, Minnesota, 55450 Zimmer Partners, LP, a Delaware limited partnership (the "Investment Manager"), Zimmer Financial Services Group LLC, a Delaware limited liability company ("ZFSG"), Zimmer Partners GP, LLC, a Delaware limited liability company (the "GP"), and Stuart J. Zimmer (collectively, the "Reporting Persons"). ZFSG is the sole member of the GP. Stuart J. Zimmer, a revocable trust for his benefit, and an irrevocable trust for his immediate family are the sole members of ZFSG. The GP is the general partner of the Investment Manager. The Investment Manager is the investment manager of ZP Master Utility Fund, Ltd. and ZP Master MidCap Fund, Ltd. and certain separately managed accounts. The address of the principal business office of each of the Reporting Persons is c/o Zimmer Partners, LP, 9 West 57th Street, 33rd Floor New York, NY 10019. Delaware N IA HC The Reporting Persons may be deemed the beneficial owners of 2,225,900 shares of Common Stock. The Reporting Persons may be deemed the beneficial owners of approximately 4.2% of the outstanding shares of Common Stock. This percentage was determined by dividing 2,225,900 by 53,316,378, which is the number of shares of Common Stock outstanding as of June 30, 2025, as reported in the Issuer's Form 10-Q filed on August 1, 2025 with the Securities and Exchange Commission. The Reporting Persons have the shared power to vote and dispose of the 2,225,900 shares of Common Stock beneficially owned. 4.2% 0 2,225,900 0 2,225,900 N Y Y Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and 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. Zimmer Partners, LP /s/ Jelena Napolitano 08/14/2025 Zimmer Financial Services Group LLC /s/ Stuart J. Zimmer 08/14/2025 Zimmer Partners GP, LLC /s/ Stuart J. Zimmer 08/14/2025 Stuart J. Zimmer /s/ Stuart J. Zimmer 08/14/2025