[Form 4] MPLX LP Insider Trading Activity

Rhea-AI Filing Summary

Frank M. Semple, a director of MPLX GP LLC, reported a transaction in MPLX common units on 08/15/2025. The filing shows an acquisition of 1,050.574 common units at a reported price of $0, and indicates 55,968.214 common units beneficially owned following the transaction as direct holdings. Additional indirect holdings are reported: 333,337 units through Frank M Semple Revocable Trust, 111,180 through Robin Y Semple 2012 Dynasty Trust, and 48,777 through EK Holdings LLC. The form is signed by an attorney-in-fact on behalf of Mr. Semple.

Insights

Securities Analyst

TL;DR: Insider reported a small acquisition of MPLX units, with clear direct and several indirect holdings disclosed.

The Form 4 documents an in-scope Section 16 reporting event: on 08/15/2025 the reporting person recorded an acquisition of 1,050.574 common units and lists 55,968.214 units as directly owned after the transaction. The filing also itemizes indirect beneficial ownership through three trusts/entities totaling 493,294 units (sum of 333,337; 111,180; 48,777). The transaction price is reported as $0, and the form is executed by an attorney-in-fact. For investors and compliance reviewers, the filing provides transparent ownership breakdown but contains no operational or financial performance information.

Corporate Governance Expert

TL;DR: Director disclosed ownership changes and multiple indirect holdings; disclosure aligns with Section 16 requirements.

The report identifies the reporting person as a director of the issuer's general partner and discloses both direct and indirect holdings across trusts and an LLC. The signature is by an authorized attorney-in-fact, which is acceptable for Form 4 execution. The filing does not include additional context about the nature of the transfer beyond the reported quantities and the $0 price; it therefore fulfills disclosure of beneficial ownership changes without further operational detail.

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
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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^*

SEMPLE FRANK M

(Last) (First) (Middle)

C/O MPLX LP

200 E. HARDIN STREET

(Street)

FINDLAY OH 45840

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
MPLX LP [ MPLX ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
08/15/2025

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

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

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

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 (Limited Partner Interests)	08/15/2025		A		1,050.574	A	$0	55,968.214	D
Common Units (Limited Partner Interests)								333,337	I	Frank M Semple Revocable Trust
Common Units (Limited Partner Interests)								111,180	I	Robin Y Semple 2012 Dynasty Trust
Common Units (Limited Partner Interests)								48,777	I	EK Holdings LLC

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

Explanation of Responses:

Remarks:

The Reporting Person is a Director of MPLX GP LLC, the general partner of the Issuer. The Issuer is managed by the directors and executive officers of MPLX GP LLC.

	/s/ Molly R. Benson, Attorney-in-Fact for Frank M. Semple	08/19/2025
	** 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.

FAQ

What transaction did Frank M. Semple report on Form 4 for MPLX (MPLX)?

The Form 4 reports an acquisition of 1,050.574 common units on 08/15/2025, with a reported price of $0.

How many MPLX common units does Frank M. Semple beneficially own after the reported transaction?

The filing shows 55,968.214 common units beneficially owned following the reported transaction as direct holdings.

Does the Form 4 disclose any indirect holdings for Frank M. Semple in MPLX?

Yes. Indirect holdings reported are 333,337 units via Frank M Semple Revocable Trust, 111,180 via Robin Y Semple 2012 Dynasty Trust, and 48,777 via EK Holdings LLC.

Who signed the Form 4 for Frank M. Semple?

The Form 4 is signed by Molly R. Benson, Attorney-in-Fact for Frank M. Semple, dated 08/19/2025.

What is the reporting person's relationship to the issuer?

The reporting person is disclosed as a Director of MPLX GP LLC, the issuer's general partner.