MPLX director updates 2026 equity unit grant

Peiffer Garry L. reported acquisition or exercise transactions in this Form 4 filing.

Accepted by SEC EDGAR 08/05/2026 - 04:15 PM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Peiffer Garry L. reported acquisition or exercise transactions in this Form 4 filing.

MPLX LP director Garry L. Peiffer received an annual 2026 equity retainer award of 2,696.3870 common units of limited partner interests on April 30, 2026, at a grant price of $0.0000 per unit. Following this award, he beneficially owned 66,768.7300 common units as of that date. This amendment corrects the amount of the 2026 equity retainer award and the reported holdings.

Insider Trade Summary

Grant/Award: 2,696.387 shares

Grant/Award 1 txn

Insider Peiffer Garry L.

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Common Units (Limited Partner Interests) F1, F2, F3	2,696.387	$0.00	$0.00

Holdings After Transaction: Common Units (Limited Partner Interests) — 66,768.73 shares (Direct)

Footnotes (3)

1. F1. Represents the reporting person's annual 2026 equity retainer award.
2. F2. This Form 4 is being amended to reflect the correct amount of the annual 2026 equity retainer award.
3. F3. This amount reflects the correct balance of securities beneficially owned as of April 30, 2026. This balance does not include any transactions that occurred after April 30, 2026.

Key Figures

Equity retainer award units: 2,696.3870 common units Grant price per unit: $0.0000 Post-award holdings: 66,768.7300 common units

3 metrics

Equity retainer award units 2,696.3870 common units Annual 2026 equity retainer award granted April 30, 2026

Grant price per unit $0.0000 Stated transaction price per MPLX LP common unit

Post-award holdings 66,768.7300 common units Beneficially owned as of April 30, 2026 following the award

Key Terms

annual 2026 equity retainer award, beneficially owned, Common Units (Limited Partner Interests)

3 terms

annual 2026 equity retainer award financial

"Represents the reporting person's annual 2026 equity retainer award."

beneficially owned regulatory

"reflects the correct balance of securities beneficially owned as of April 30, 2026"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Common Units (Limited Partner Interests) financial

"Security title: Common Units (Limited Partner Interests) of MPLX LP"

FAQ

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

What insider transaction did MPLX (MPLX) report for Garry L. Peiffer?

MPLX LP reported that director Garry L. Peiffer received an annual 2026 equity retainer award of 2,696.3870 common units on April 30, 2026. The units are common units representing limited partner interests, granted as part of his director compensation.

How many MPLX (MPLX) units does Garry L. Peiffer hold after this amendment?

After the corrected 2026 equity retainer award, Garry L. Peiffer beneficially owned 66,768.7300 common units of MPLX LP. This balance is reported as of April 30, 2026 and excludes any transactions that occurred after that date.

Why was the MPLX (MPLX) Form 4 amended for Garry L. Peiffer?

The Form 4 was amended to reflect the correct amount of Garry L. Peiffer’s annual 2026 equity retainer award. The amendment also updates the balance of securities beneficially owned as of April 30, 2026, based on this corrected award amount.

What price per unit was reported for Garry L. Peiffer’s MPLX (MPLX) equity award?

The annual 2026 equity retainer award for Garry L. Peiffer was reported at a grant price of $0.0000 per common unit. This reflects a compensation-related equity grant rather than an open-market purchase of MPLX LP common units.

What type of security did Garry L. Peiffer receive from MPLX (MPLX)?

Garry L. Peiffer received Common Units (Limited Partner Interests) of MPLX LP as his 2026 equity retainer award. These units represent limited partner interests in the partnership and are part of his annual director equity compensation.

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

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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^*

Peiffer Garry L.

(Last) (First) (Middle)

C/O MPLX LP

200 E. HARDIN STREET

(Street)

FINDLAY OHIO 45840

(City) (State) (Zip)

UNITED STATES

(Country)

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)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/30/2026

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

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

4. If Amendment, Date of Original Filed (Month/Day/Year)
05/04/2026

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)	04/30/2026		A		2,696.387(1)(2)	A	$0	66,768.73(3)	D

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:

1. Represents the reporting person's annual 2026 equity retainer award.

2. This Form 4 is being amended to reflect the correct amount of the annual 2026 equity retainer award.

3. This amount reflects the correct balance of securities beneficially owned as of April 30, 2026. This balance does not include any transactions that occurred after April 30, 2026.

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 Garry L. Peiffer	08/05/2026
	** 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)