MPLX LP

5. Related Party Agreements and Transactions

MPLX engages in transactions with both MPC and certain of its equity method investments as part of its normal business; however, transactions with MPC make up the majority of MPLX’s related party transactions. Transactions with related parties are further described below.

Commercial Agreements

MPLX has various long-term, fee-based commercial agreements with MPC. Under these agreements, MPLX provides transportation, gathering, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum quarterly throughput volumes on crude oil and refined products and other fees for storage capacity; operating and management fees; and reimbursements for certain direct and indirect costs. MPC has also committed to provide a fixed fee for 100 percent of available capacity for boats, barges and third-party chartered equipment under a marine transportation services agreement. In addition, MPLX has obligations to MPC for services provided to MPLX by MPC under omnibus and employee services agreements as well as various other agreements.

During the second quarter of 2026, a refining logistics agreement between MPLX and MPC was renewed, which required reassessment of the agreement under ASC 842. As a result of the reassessment, the lease was reclassified from sales-type to operating lease (see Note 16).

Related Party Loan

MPLX is party to a loan agreement with MPC (the “MPC Loan Agreement”). Under the terms of the MPC Loan Agreement, MPC extends loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC. The borrowing capacity of the MPC Loan Agreement is $1.5 billion aggregate principal amount of all loans outstanding at any one time. The MPC Loan Agreement is scheduled to expire, and any borrowings under the loan agreement are scheduled to mature and become due and payable, on July 31, 2029, provided that MPC may demand payment of all or any portion of the outstanding principal amount of the loan, together with all accrued and unpaid interest and other amounts (if any), at any time prior to maturity. Borrowings under the MPC Loan Agreement bear interest atone-month term SOFR plus 1.25 percent or such lower rate as would be applicable to such loans under MPLX’s bank revolving credit facility as discussed in Note 12. On October 30, 2026, MPLX and MPC amended and restated the MPC Loan Agreement to increase the borrowing capacity from $1.5 billion to $2.5 billion and to extend the term of the intercompany loan agreement from July 31, 2029, to October 30, 2031.

Activity on the MPC Loan Agreement for the nine months ended September 30, 2026 and September 30, 2025 is summarized below.

Related Party Revenue and Other Income

Related party revenue consists primarily of revenue recognized from commercial agreements with MPC as well as fees charged under operating agreements with MPC and our equity affiliates as discussed above.

Certain product sales to MPC and other related parties net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three and nine months ended September 30, 2026, these sales totaled $436 million and $993 million, respectively. For the three and nine months ended September 30, 2025, these sales totaled $151 million and $476 million, respectively.

See Note 11 for additional details regarding related party derivative activity with MPC.

Related Party Expenses

MPC charges MPLX for executive management services and certain general and administrative services provided to MPLX under the terms of our omnibus agreements (“Omnibus charges”), for certain employee services provided to MPLX under employee services agreements (“ESA charges”) and fees paid under co-location agreements and ground lease agreements. Omnibus charges and ESA charges are classified as Rental cost of sales - related parties, Purchases - related parties, or General and administrative expenses depending on the nature of the asset or activity with which the costs are associated. Additionally, we incur costs under agreements for transportation and processing services with certain of our unconsolidated affiliates.

In addition to these agreements, MPLX purchases products from MPC, makes payments to MPC in its capacity as general contractor to MPLX, and has certain rent and lease agreements with MPC.

For the three and nine months ended September 30, 2026, General and administrative expenses incurred from MPC totaled $104 million and $274 million, respectively. For the three and nine months ended September 30, 2025, General and administrative expenses incurred from MPC totaled $80 million and $236 million, respectively.

Some charges incurred under the omnibus and employee service agreements are related to engineering services and are associated with assets under construction. These charges are added to Property, plant and equipment, net on the Consolidated Balance Sheets. For the three and nine months ended September 30, 2026, these charges totaled $73 million and $190 million, respectively. For the three and nine months ended September 30, 2025, these charges totaled $64 million and $159 million, respectively.

Related Party Assets and Liabilities

Assets and liabilities with related parties appearing in the Consolidated Balance Sheets are detailed in the table below. This table identifies the various components of related party assets and liabilities, including those associated with leases and deferred revenue.

(1)There wereno borrowings outstanding on the MPC Loan Agreement as of September 30, 2026 or December 31, 2025.