Mach Natural Resources LP美股招股说明书(2026-04-06版)

Filed Pursuant to Rule 424(b)(3)Registration No. 333-291166 The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectussupplement and the accompanying prospectus are part of an effective registration statement filed with the Securities andExchange Commission. This preliminary prospectus supplement and the accompanying prospectus are not offers to sell norsolicitations of offers to buy these securities in any jurisdiction where such offer or sale is not permitted. SUBJECT TO COMPLETION, DATED APRIL 6, 2026 PROSPECTUS SUPPLEMENT TO PROSPECTUS DATED DECEMBER 12, 2025 Mach Natural Resources LP 9,000,000 Common UnitsRepresenting Limited Partner Interests The selling unitholders identified in this prospectus supplement are offering 9,000,000 common units representing limitedpartner interests in Mach Natural Resources LP. We will not receive any of the proceeds from the sale of our common units by theselling unitholders. Our common units are listed on the New York Stock Exchange (the “NYSE”) under the symbol “MNR”. On April 2, 2026,the last reported sale price of our common units on the NYSE was $14.06 per unit. Tom L. Ward, our Chief Executive Officer, through the Tom L. Ward 1992 Revocable Trust and the Tom L. Ward FamilyFoundation and certain other entities affiliated with Mr. Ward, which are not controlled by Mr. Ward (the “Ward Affiliated Entities”),have indicated an interest in purchasing up to $2.0 million of the common units being offered hereby in this offering at the publicoffering price, or approximately 142,248 common units (assuming an offering price equal to the last reported sale price of ourcommon units on the NYSE on April 2, 2026 of $14.06 per unit). However, because indications of interest are not binding agreementsor commitments to purchase, the underwriter could determine to sell to Mr. Ward or the Ward Affiliated Entities (or Mr. Ward and theWard Affiliated Entities could determine to purchase) fewer or no shares in this offering. Investing in our common units involves risks. Limited partnerships are inherently different from corporations. Pleaseread “Risk Factors” beginning on page S-6 of this prospectus supplement and under similar headings in the other documentsincorporated by reference into this prospectus supplement. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminaloffense. Per UnitTotalPrice to Public(1)(2)$$Underwriting Discounts and Commissions(2)$$Proceeds to the Selling Unitholders, Before Expenses$$ (1)Mr. Ward and the Ward Affiliated Entities have indicated an interest in purchasing up to $2.0 million of the common unitsbeing offered hereby in this offering at the public offering price, or approximately 142,248 common units (assuming anoffering price equal to the last reported sale price of our common units on the NYSE on April 2, 2026 of $14.06 per unit).However, because indications of interest are not binding agreements or commitments to purchase, the underwriter coulddetermine to sell to Mr. Ward or the Ward Affiliated Entities (or Mr. Ward and the Ward Affiliated Entities could determine topurchase) fewer or no shares in this offering. (2)See “Underwriting” for additional information regarding underwriting compensation. The selling unitholders have granted the underwriter a 30-day option to purchase up to an additional 1,350,000 common unitson the same terms and conditions as set forth above. The underwriter expects to deliver the common units on or about, 2026. Morgan Stanley TABLE OF CONTENTS Prospectus Supplement BASIS OF PRESENTATIONS-iiABOUT THIS PROSPECTUS SUPPLEMENTS-iiiINDUSTRY AND MARKET DATAS-ivCAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSS-vSUMMARYS-1RISK FACTORSS-6USE OF PROCEEDSS-8SELLING UNITHOLDERSS-9MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCESS-10UNDERWRITINGS-11LEGAL MATTERSS-17EXPERTSS-18WHERE YOU CAN FIND MORE INFORMATIONS-19INFORMATION WE INCORPORATE BY REFERENCES-20 Prospectus PageABOUT THIS PROSPECTUS1WHERE YOU CAN FIND MORE INFORMATION2INFORMATION WE INCORPORATE BY REFERENCE3CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS4ABOUT MACH NATURAL RESOURCES LP7RISK FACTORS8USE OF PROCEEDS9SELLING UNITHOLDERS10DESCRIPTION OF THE COMMON UNITS12CASH DISTRIBUTION POLICY14THE PARTNERSHIP AGREEMENT15MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES28INVESTMENT IN MACH NATURAL RESOURCES LP BY EMPLOYEE BENEFIT PLANS48PLAN OF DISTRIBUTION50LEGAL MATTERS54EXPERTS54 BASIS OF PRESENTATION On September 16, 2025, we acquired (i) certain rights, title and interests in oil and gas properties, rights and related assetslocated in certain designated lands in the San Juan Basin of New Mexico and Colorado from VEPU Inc. and Simlog Inc. (the “IKAVAssets”) and (ii) certain rights, title and interests in oil