MPLX director receives equity grant of 1,303 units

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

Accepted by SEC EDGAR 05/19/2026 - 04:13 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 reported receiving additional common units as equity compensation and updated his holdings. He was granted 1,303.501 common units of MPLX LP at no cost, bringing his directly held units to 67,622.833. He also reported indirect ownership of 68,497 common units held by the Garry L. Peiffer Revocable Trust.

Insider Trade Summary

Grant/Award: 1,303.501 shares

Grant/Award 1 txn

Insider Peiffer Garry L.

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Common Units (Limited Partner Interests)	1,303.501	$0.00	$0.00
Holding	Common Units (Limited Partner Interests)	--	--	--

Holdings After Transaction: Common Units (Limited Partner Interests) — 67,622.833 shares (Direct); Common Units (Limited Partner Interests) — 68,497 shares (Indirect, By Revocable Trust)

Footnotes (1)

1. F1. By Garry L. Peiffer Revocable Trust.

Key Figures

Equity grant size: 1,303.501 units Grant price: $0.00 per unit Direct holdings after grant: 67,622.833 units +1 more

4 metrics

Equity grant size 1,303.501 units Common units granted on May 15, 2026

Grant price $0.00 per unit Price for awarded common units

Direct holdings after grant 67,622.833 units Direct MPLX common units following transaction

Indirect trust holdings 68,497 units Units held by Garry L. Peiffer Revocable Trust

Key Terms

Common Units (Limited Partner Interests), Grant, award, or other acquisition, Revocable Trust, indirect ownership

4 terms

Common Units (Limited Partner Interests) financial

"security_title: "Common Units (Limited Partner Interests)""

Grant, award, or other acquisition financial

"transaction_code_description: "Grant, award, or other acquisition""

Revocable Trust financial

"nature_of_ownership: "By Revocable Trust""

A revocable trust is a legal arrangement where the person who creates it keeps control and can change or cancel the trust at any time, while naming who will manage and receive the assets later. Think of it like a flexible folder for your investments and property that can be relabeled or reworked as circumstances change; it matters to investors because it determines how ownership is recorded, how easily assets transfer on incapacity or death, and whether holdings bypass public probate proceedings.

indirect ownership financial

"ownership_type: "indirect""

FAQ

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

What insider transaction did MPLX director Garry L. Peiffer report?

MPLX director Garry L. Peiffer reported an equity grant of 1,303.501 common units. These units were acquired at a price of $0.00 per unit as compensation, increasing his directly held MPLX LP common units to 67,622.833 after the transaction.

At what price were the new MPLX LP units granted to Garry L. Peiffer?

The newly granted MPLX LP common units to Garry L. Peiffer had a transaction price of $0.00 per unit. This indicates a compensation-related award rather than an open-market purchase, reflecting additional equity granted by the partnership instead of cash investment.

How many MPLX LP units does Garry L. Peiffer hold directly after this Form 4?

After the reported transaction, Garry L. Peiffer directly holds 67,622.833 MPLX LP common units. This figure reflects his position following the 1,303.501-unit equity grant recorded on May 15, 2026, and represents his direct ownership separate from trust-held units.

What indirect MPLX LP holdings are reported for Garry L. Peiffer?

The Form 4 shows 68,497 MPLX LP common units held indirectly through the Garry L. Peiffer Revocable Trust. This trust-related position is reported as indirect ownership, separate from his directly owned 67,622.833 units following the compensation grant on May 15, 2026.

Was Garry L. Peiffer’s MPLX unit transaction a market buy or compensation grant?

The transaction is classified as a grant or award acquisition, not a market buy. Code “A” indicates a compensation-related grant of 1,303.501 MPLX common units at $0.00 per unit, rather than an open-market purchase on a stock exchange.

Does the MPLX Form 4 show any insider sales by Garry L. Peiffer?

The Form 4 does not report any sales by Garry L. Peiffer. It shows one compensation-related acquisition of 1,303.501 MPLX common units and an entry reflecting 68,497 units held indirectly by his revocable trust, with no dispose or sell transactions listed.

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)
05/15/2026

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)

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)	05/15/2026		A		1,303.501	A	$0	67,622.833	D
Common Units (Limited Partner Interests)								68,497	I	By Revocable Trust(1)

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. By Garry L. Peiffer Revocable Trust.

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	05/19/2026
	** 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)