X0202 SCHEDULE 13G 0002153177 XXXXXXXX LIVE Class A Common Stock, par value $0.0001 09/10/2026 0001698990 Magnolia Oil & Gas Corp 559663109 Nine Greenway Plaza, Suite 1300 Houston TX 77046 Rule 13d-1(c) WildFire Energy I LLC b DE 0.00 32203000.00 0.00 32203000.00 32203000.00 N 11.96 OO The reported percentage is calculated based on 236,968,592 shares of Class A common stock ("Common Stock") outstanding as of August 3, 2026, as reported in the Issuer's Form 10-Q filed with the Securities and Exchange Commission ("SEC") on August 6, 2026, as increased by 32,203,000 shares of Common Stock issued to the Reporting Person on September 10, 2026. Hawkwood HoldCo, L.P. b DE 0.00 32203000.00 0.00 32203000.00 32203000.00 N 11.96 PN The reported percentage is calculated based on 236,968,592 shares of Common Stock outstanding as of August 3, 2026, as reported in the Issuer's Form 10-Q filed with the SEC on August 6, 2026, as increased by 32,203,000 shares of Common Stock issued to WildFire Energy I LLC on September 10, 2026. Hawkwood HoldCo GP, LLC b DE 0.00 32203000.00 0.00 32203000.00 32203000.00 N 11.96 OO The reported percentage is calculated based on 236,968,592 shares of Common Stock outstanding as of August 3, 2026, as reported in the Issuer's Form 10-Q filed with the SEC on August 6, 2026, as increased by 32,203,000 shares of Common Stock issued to WildFire Energy I LLC on September 10, 2026. Warburg Pincus & Company US, LLC b DE 0.00 32203000.00 0.00 32203000.00 32203000.00 N 11.96 OO The reported percentage is calculated based on 236,968,592 shares of Common Stock outstanding as of August 3, 2026, as reported in the Issuer's Form 10-Q filed with the SEC on August 6, 2026, as increased by 32,203,000 shares of Common Stock issued to WildFire Energy I LLC on September 10, 2026. Kayne Anderson Capital Advisors, L.P. b DE 0.00 32203000.00 0.00 32203000.00 32203000.00 N 11.96 IA The reported percentage is calculated based on 236,968,592 shares of Common Stock outstanding as of August 3, 2026, as reported in the Issuer's Form 10-Q filed with the SEC on August 6, 2026, as increased by 32,203,000 shares of Common Stock issued to WildFire Energy I LLC on September 10, 2026. Magnolia Oil & Gas Corp Nine Greenway Plaza, Suite 1300, Houston, Texas 77046 This statement is being jointly filed by each of the persons below pursuant to Rule 13d-1(k) promulgated by the SEC pursuant to Section 13 of the Act, all of whom together are referred to herein as the "Reporting Persons": (i) WildFire Energy I LLC; (ii) Hawkwood HoldCo, L.P.; (iii) Hawkwood HoldCo GP, LLC; (iv) Warburg Pincus & Company US, LLC; and (v) Kayne Anderson Capital Advisors, L.P. (i) The address of WildFire Energy I LLC is 920 Memorial City Way, Suite 1400, Houston, TX 77024. (ii) The address of Hawkwood HoldCo, L.P., Hawkwood HoldCo GP, LLC and Warburg Pincus & Company US, LLC is c/o Warburg Pincus LLC, 450 Lexington Ave, New York, NY 10017. (iii) The address of Kayne Anderson Capital Advisors, L.P. is 2121 Avenue of the Stars, 9th Floor, Los Angeles, CA 90067. See response to row 4 on each cover page hereto. Y See response to row 9 on each cover page hereto. The reported securities are directly held by WildFire Energy I LLC. Hawkwood HoldCo, L.P., Kayne Private Energy Income Fund II, L.P., Kayne Private Energy Income Fund II-B, L.P., Kayne Anderson Energy Fund VIII, L.P. and certain management individuals hold 100% of the equity interests in WildFire Energy I LLC. Warburg Pincus & Company US, LLC ("Warburg Pincus") is the general partner of Warburg Pincus Partners II (US), L.P., which is the managing member of Warburg Pincus Partners (E&P) XI LLC, which is the sole member of Warburg Pincus (E&P) XI LLC, which is the general partner of Warburg Pincus (E&P) XI, L.P., which is the general partner of Warburg Pincus Private Equity (E&P) XI - A, L.P., which is the managing member of Hawkwood HoldCo GP, LLC, which is the general partner of Hawkwood HoldCo, L.P., which holds the securities on behalf of various funds and accounts indirectly managed by Warburg Pincus (collectively, the "Warburg Entities"). Kayne Private Energy Income Fund II, L.P., Kayne Private Energy Income Fund II-B, L.P. and Kayne Anderson Energy Fund VIII, L.P. are managed, with discretion to purchase or sell securities, by Kayne Anderson Capital Advisors, L.P. (or controlled affiliates thereof) (collectively, the "Kayne Entities"), as a registered investment adviser. The Warburg Entities and Kayne Entities jointly control WildFire Energy I LLC. Accordingly, the Warburg Entities and the Kayne Entities may be deemed to share voting and dispositive power with respect to the reported securities. The filing of this Statement shall not be deemed an admission of beneficial ownership by any of the Reporting Persons for purposes of Section 13(d) or 13(g), or for any other purpose. See response to row 11 on each cover page hereto. See response to row 5 on each cover page hereto. See response to row 6 on each cover page hereto. See response to row 7 on each cover page hereto. See response to row 8 on each cover page hereto. 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 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 99.1 Joint Filing Agreement, dated September 16, 2026, by and among the Reporting Persons. WildFire Energy I LLC /s/ Anthony F. Bahr 09/16/2026 Hawkwood HoldCo, L.P. /s/ Hawkwood HoldCo GP, LLC 09/16/2026 /s/ Warburg Pincus Private Equity (E&P) XI - A, L.P. 09/16/2026 /s/ Warburg Pincus (E&P) XI, L.P. 09/16/2026 /s/ Warburg Pincus (E&P) XI LLC 09/16/2026 /s/ Warburg Pincus Partners (E&P) XI LLC 09/16/2026 /s/ Warburg Pincus Partners II (US), L.P. 09/16/2026 /s/ Warburg Pincus & Company US, LLC 09/16/2026 /s/ Harsha Marti 09/16/2026 Hawkwood HoldCo GP, LLC /s/ Warburg Pincus Private Equity (E&P) XI - A, L.P. 09/16/2026 /s/ Warburg Pincus (E&P) XI, L.P. 09/16/2026 /s/ Warburg Pincus (E&P) XI LLC 09/16/2026 /s/ Warburg Pincus Partners (E&P) XI LLC 09/16/2026 /s/ Warburg Pincus Partners II (US), L.P. 09/16/2026 /s/ Warburg Pincus & Company US, LLC 09/16/2026 /s/ Harsha Marti 09/16/2026 Warburg Pincus & Company US, LLC /s/ Harsha Marti 09/16/2026 Kayne Anderson Capital Advisors, L.P. /s/ Daniel Weingeist 09/16/2026