Mach Natural director buys 34.5K units at $11

Director and ten percent owner–affiliated entities added Mach Natural Resources common units through open-market purchases, increasing already large indirect holdings.

Rhea-AI Filing Summary

Mach Natural Resources LP (MNR) reported that director and ten percent owner William W. McMullen and affiliated entity Bayou City Energy Management LLC (BCEM) purchased a total of 34,514 Common Units on September 15, 2026 in open-market or private transactions. McMullen acquired 22,124 units at $11.25 per unit directly, and BCEM acquired 12,390 units at a weighted average price between $11.28 and $11.30 per unit. Following the reported indirect transaction, 74,872,307 Common Units are reported as directly held in the aggregate by BCE Mach Aggregator LLC and BCEM, which McMullen may be deemed to beneficially own but for which he disclaims beneficial ownership except to the extent of his pecuniary interest. No Rule 10b5-1 trading plan is reported for these purchases.

Insider Trade Summary

Net Buyer: 34,514 shares

Net Buy 2 txns

Insider McMullen William Wallace, BAYOU CITY ENERGY MANAGEMENT LLC

Role Director, 10% Owner | 10% Owner

Bought 34,514 shs ($389K)

Type	Security	Shares	Price	Value
Purchase	Common Units	22,124	$11.25	$249K
Purchase	Common Units F1, F2	12,390	$11.30	$140K

Holdings After Transaction: Common Units — 22,124 shares (Direct); Common Units — 74,872,307 shares (Indirect, See footnote)

Footnotes (2)

1. F1. The price reported in Column 4 is a weighted average price. These common units were purchased by Bayou City Energy Management LLC ("BCEM") in multiple transactions at prices ranging from $11.28 to $11.30, inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of common units purchased at each separate price within the ranges set forth in this footnote (1) to this Form 4.
2. F2. The reported common units are directly held 74,835,939 by BCE Mach Aggregator LLC ("BCE Aggregator") and 36,368 by BCEM. BCE Aggregator is indirectly managed by BCEM. William W. McMullen is the Managing Partner of BCEM. Accordingly, William W. McMullen may be deemed to beneficially own the securities directly held by BCE Aggregator and BCEM, as applicable, but disclaims beneficial ownership of such common units except to the extent of his pecuniary interest therein.

Key Figures

Direct units purchased: 22,124 Common Units Direct purchase price: $11.25 per unit Indirect units purchased: 12,390 Common Units +5 more

8 metrics

Direct units purchased 22,124 Common Units Purchased directly by William W. McMullen on September 15, 2026

Direct purchase price $11.25 per unit Price paid for 22,124 Common Units by McMullen on September 15, 2026

Indirect units purchased 12,390 Common Units Purchased by Bayou City Energy Management LLC on September 15, 2026

Indirect weighted average price range $11.28–$11.30 per unit Weighted average purchase range for 12,390 units bought by BCEM

Total units purchased in filing 34,514 Common Units Aggregate of direct and indirect purchases reported for September 15, 2026

Units held by BCE Mach Aggregator LLC 74,835,939 Common Units Directly held by BCE Mach Aggregator LLC after the reported transactions

Units held by Bayou City Energy Management LLC 36,368 Common Units Directly held by Bayou City Energy Management LLC after the reported transactions

Total units held by BCE Mach Aggregator and BCEM 74,872,307 Common Units Combined holdings directly at BCE Mach Aggregator LLC and BCEM

Key Terms

weighted average price, beneficially own, pecuniary interest, indirectly managed, +1 more

5 terms

weighted average price financial

"These common units were purchased by BCEM in multiple transactions at prices ranging from $11.28 to $11.30, inclusive."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

beneficially own financial

"Accordingly, William W. McMullen may be deemed to beneficially own the securities directly held by BCE Aggregator and BCEM."

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

pecuniary interest financial

"but disclaims beneficial ownership of such common units except to the extent of his pecuniary interest therein."

indirectly managed financial

"The reported common units are directly held 74,835,939 by BCE Mach Aggregator LLC and 36,368 by BCEM. BCE Aggregator is indirectly managed by BCEM."

ten percent owner regulatory

"McMullen William Wallace is indicated as a director and ten percent owner of the issuer."

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider purchases of MNR units were reported on September 15, 2026?

On September 15, 2026, 34,514 Mach Natural Resources LP Common Units were purchased in total: 22,124 units at $11.25 per unit directly by William W. McMullen and 12,390 units indirectly through Bayou City Energy Management LLC at a weighted average price between $11.28 and $11.30.

How many MNR units are indirectly held by entities associated with William W. McMullen after these transactions?

After the reported indirect transaction, a total of 74,872,307 Common Units are directly held by 74,835,939 units at BCE Mach Aggregator LLC and 36,368 units at Bayou City Energy Management LLC. McMullen may be deemed to beneficially own these but disclaims ownership except for his pecuniary interest.

Did the MNR insider trades on September 15, 2026 use a Rule 10b5-1 trading plan?

No. The filing indicates that the Rule 10b5-1 checkbox is not marked, and there is no footnote stating that the September 15, 2026 transactions were made pursuant to a Rule 10b5-1 or other pre-arranged trading plan.

What prices were paid for the MNR Common Units in the reported insider transactions?

William W. McMullen bought 22,124 Common Units at $11.25 per unit. Bayou City Energy Management LLC bought 12,390 Common Units at a weighted average price, with individual trades occurring in a range from $11.28 to $11.30 per unit.

Who executed the indirect purchases of MNR units related to William W. McMullen?

The indirect purchase of 12,390 Common Units was made by Bayou City Energy Management LLC (BCEM). A related entity, BCE Mach Aggregator LLC, directly holds an additional 74,835,939 Common Units, both entities being associated with McMullen through management relationships described in the filing.

Does William W. McMullen fully own all MNR units held by BCE Mach Aggregator and BCEM?

No. The filing states that McMullen may be deemed to beneficially own the units held by BCE Mach Aggregator and BCEM, but he disclaims beneficial ownership of those units except to the extent of his pecuniary interest in them.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/17/2026 - 05:11 PM Accepted by SEC EDGAR 09/17/2026 - 05:11 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

McMullen William Wallace

(Last) (First) (Middle)

14201 WIRELESS WAY

SUITE 300

(Street)

OKLAHOMA CITY OKLAHOMA 73134

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
MACH NATURAL RESOURCES LP [ MNR ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	X	10% Owner
	Officer (give title below)	X	Other (specify below)
			See Remarks

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/15/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Units	09/15/2026		P		22,124	A	$11.25	22,124	D
Common Units	09/15/2026		P		12,390	A	$11.3(1)	74,872,307	I	See footnote(1)(2)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person^*

McMullen William Wallace

(Last) (First) (Middle)

14201 WIRELESS WAY

SUITE 300

(Street)

OKLAHOMA CITY OKLAHOMA 73134

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)	X	Other (specify below)
			See Remarks

1. Name and Address of Reporting Person^*

BAYOU CITY ENERGY MANAGEMENT LLC

(Last) (First) (Middle)

C/O BAYOU CITY ENERGY, L.P.

2229 SAN FELIPE STREET, SUITE 1075

(Street)

HOUSTON TEXAS 77019

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. The price reported in Column 4 is a weighted average price. These common units were purchased by Bayou City Energy Management LLC ("BCEM") in multiple transactions at prices ranging from $11.28 to $11.30, inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of common units purchased at each separate price within the ranges set forth in this footnote (1) to this Form 4.

2. The reported common units are directly held 74,835,939 by BCE Mach Aggregator LLC ("BCE Aggregator") and 36,368 by BCEM. BCE Aggregator is indirectly managed by BCEM. William W. McMullen is the Managing Partner of BCEM. Accordingly, William W. McMullen may be deemed to beneficially own the securities directly held by BCE Aggregator and BCEM, as applicable, but disclaims beneficial ownership of such common units except to the extent of his pecuniary interest therein.

Remarks:

William W. McMullen is a Director of Mach Natural Resources GP LLC, the general partner of the Issuer (the "General Partner"). The Issuer is managed by the directors and executive officers of the General Partner.

	William W. McMullen, By: /s/ William W. McMullen	09/17/2026
	Bayou City Energy Management LLC, By: /s/ William W. McMullen, Name: William W. McMullen, Title: Managing Partner	09/17/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)