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~~the ~~(Date~~Securities ofExchange ~~earliest~~Act ~~event~~of ~~reported) February 3, 2026~~ 1934

Date of Report (Date of earliest event reported): February ~~_____________________________________________~~12, 2026

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.)

Delaware

001-35714

27-0005456

(State or other jurisdictionof incorporation)

(Commission File Number)

(IRS EmployerIdentification 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	Tradingsymbol(s)	Name of each exchange on which registered
Common Units Representing Limited Partnership Interests	MPLX	New York Stock Exchange

☐	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 8.01 Other Events.

~~Item~~MPLX ~~2.02~~LP ~~Results~~(the of“Issuer”) ~~Operations~~is ~~and~~filing ~~Financial~~herewith ~~Condition~~the following exhibits to its Registration Statement on Form S-3 (Registration No. 333-271922):

On1. Underwriting Agreement, dated as of February 3 5, 2026, ~~MPLX~~by LPand ~~issued~~among athe ~~press~~Issuer, ~~release~~MPLX ~~announcing~~GP ~~its~~LLC, ~~financial~~the ~~results~~general ~~for~~partner of the ~~quarter~~Issuer, and ~~year~~each ~~ended~~of ~~December 31,~~Citigroup ~~2025.~~Global ~~The~~Markets ~~press~~Inc., ~~release~~Barclays isCapital ~~furnished~~Inc., asMUFG ~~Exhibit~~Securities 99Americas Inc.1, toand ~~this~~RBC ~~Current~~Capital ~~Report~~Markets, onLLC, ~~Form~~acting ~~8-K~~as ~~and~~representatives isof ~~incorporated~~the ~~herein~~several byunderwriters ~~reference.~~named therein;

~~Information in this Item~~ 2.02 ~~and~~Thirty-Sixth ~~Exhibit~~Supplemental ~~99.1~~Indenture, ofdated ~~Item 9.01~~as ~~below shall not be deemed “filed” for the purposes~~ of ~~Section 18~~February ~~of the Securities Exchange Act of 1934~~12, ~~as amended (the “Exchange Act”)~~2026, orby ~~otherwise~~and ~~incorporated~~between bythe ~~reference~~Issuer ~~into~~and ~~any~~The ~~filing~~Bank ~~pursuant~~of toNew ~~the~~York ~~Securities~~Mellon ~~Act~~Trust ~~of 1933~~Company, ~~as amended~~N.A., ~~or the Exchange Act except~~ as ~~otherwise~~Trustee ~~expressly~~(including ~~stated~~Form inof ~~such a filing.~~Note);

~~Item 9~~3.01 ~~Financial~~Thirty-Seventh ~~Statements~~Supplemental Indenture, dated as of February 12, 2026, by and ~~Exhibits~~between the Issuer and The Bank of New York Mellon Trust Company, N.A., as Trustee (including Form of Note); and

Opinion of Jones Day.

Item 9.01

Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number		Description
ExhibitNumber	Description
99.1		Press Release issued by MPLX LP on February 3, 2026
1.1	Underwriting Agreement, dated as of February 5, 2026, by and among the Issuer, MPLX GP LLC, the general partner of the Issuer, and each of Citigroup Global Markets Inc., Barclays Capital Inc., MUFG Securities Americas Inc., and RBC Capital Markets, LLC, acting as representatives of the several underwriters named therein
104		Cover Page Interactive Data File (embedded within the Inline XBRL document)
4.1	Thirty-Sixth Supplemental Indenture, dated as of February 12, 2026, by and between the Issuer and The Bank of New York Mellon Trust Company, N.A., as Trustee (including Form of Note)
4.2	Thirty-Seventh Supplemental Indenture, dated as of February 12, 2026, by and between the Issuer and The Bank of New York Mellon Trust Company, N.A., as Trustee (including Form of Note)
5.1	Opinion of Jones Day
23.1	Consent of Jones Day (included in Exhibit 5.1)
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~~	MPLX LP
	~~By:~~	By:	MPLX GP LLC, its General Partner	~~MPLX GP LLC, its General Partner~~
Date: February 3, 2026	By:			/s/ C. Kristopher Hagedorn
Date: February 12, 2026		By:	/s/ Molly R. Benson
				Name: C. Kristopher Hagedorn
		Name:	Molly R. Benson
				Title: Executive Vice President and Chief Financial Officer
		Title:	Chief Legal Officer and Corporate Secretary

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