[8-K] MPLX LP Reports Material Event

Rhea-AI Filing Summary

MPLX LP announced a leadership transition. The board elected Maryann T. Mannen, currently President and Chief Executive Officer and a director of MPLX GP LLC, as Chairman of the Board effective January 1, 2026. She will add the Chairman role to her existing responsibilities.

Michael J. Hennigan notified the Partnership of his retirement as Executive Chairman and as a director of MPLX GP, also effective January 1, 2026. With his retirement, the board size will be reduced to 10 directors as of the effective date. The Partnership issued a press release on November 4, 2025, detailing these changes.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

_____________________________________________

FORM 8-K

_____________________________________________

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported) October 29, 2025

 _____________________________________________

MPLX LP

(Exact name of registrant as specified in its charter)

_____________________________________________

Delaware

001-35714

27-0005456

(State or other jurisdiction of incorporation)

(Commission File Number)

(IRS Employer Identification No.)

200 E. Hardin Street, Findlay, Ohio 45840

(Address of principal executive offices) (Zip code)

Registrant’s telephone number, including area code: (419) 422-2121

_____________________________________________

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: 

☐			Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
☐			Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
☐			Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
☐			Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:
Title of each class			Trading symbol(s)			Name of each exchange on which registered
Common Units Representing Limited Partnership Interests			MPLX			New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

☐

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On October 29, 2025, the board of directors of MPLX GP LLC ("MPLX GP"), the general partner of MPLX LP (the “Partnership”), elected Maryann T. Mannen, President and Chief Executive Officer, and member of the board of directors of MPLX GP, as Chairman of the Board, effective as of January 1, 2026 (the “Effective Date”). Ms. Mannen will assume the role of Chairman of the Board in addition to her current responsibilities.

Ms. Mannen will succeed Michael J. Hennigan, who notified the Partnership on October 29, 2025 of his intention to retire as Executive Chairman and as a member of the board of directors of MPLX GP as of the Effective Date.

With the retirement of Mr. Hennigan, the size of the board of directors of MPLX GP will be decreased to 10 directors as of the Effective Date.

Item 8.01 Other Events.

On November 4, 2025, the Partnership issued a press release announcing the changes reported above. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number						Description
99.1						Press release issued by MPLX LP on November 4, 2025
104						Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

			MPLX LP
			By:						MPLX GP LLC, its General Partner
Date: November 4, 2025			By:						/s/ Molly R. Benson
									Name: Molly R. Benson
									Title: Chief Legal Officer and Corporate Secretary

FAQ

What leadership change did MPLX (MPLX) announce?

Maryann T. Mannen was elected Chairman of the Board, effective January 1, 2026, in addition to her roles as President, CEO, and director.

Who is retiring from MPLX’s board and when?

Michael J. Hennigan will retire as Executive Chairman and as a director effective January 1, 2026.

Will Maryann T. Mannen keep her current roles at MPLX?

Yes. She will serve as Chairman while continuing as President and Chief Executive Officer and as a director.

How will MPLX’s board size change?

The board will be reduced to 10 directors as of January 1, 2026.

Did MPLX issue a press release about these changes?

Yes. A press release was issued on November 4, 2025 and is attached as Exhibit 99.1.

Which entity governs MPLX LP?

MPLX LP is governed by its general partner, MPLX GP LLC.