MPLX LP

9. Series A Preferred Units

Private Placement of Preferred Units

On May 13, 2016, MPLX completed the private placement of approximately 30.8 million 6.5 percent Series A Convertible preferred units for a cash purchase price of $32.50 per unit. The aggregate net proceeds of approximately $984 million from the sale of the Series A preferred units were used for capital expenditures, repayment of debt and general business purposes.

Preferred Unit Conversions

The following conversions were executed in accordance with the conversion provisions outlined in our Partnership Agreement. During the years ended December 31, 2024 and 2023, certain Series A preferred unitholders exercised their rights to convert their Series A preferred units into 21 million common units and 2 million common units, respectively. On February 11, 2025,

MPLX exercised its right to convert the remaining 6 million outstanding Series A preferred units into common units. As a result, there were no Series A preferred units outstanding at December 31, 2025.

For a summary of changes in the redeemable preferred balance for the years ended December 31, 2025, 2024 and 2023, see the Consolidated Statements of Equity.

Preferred Unit Distribution Rights

Prior to conversion, the Series A preferred units ranked senior to all common units and pari passu with all Series B preferred units with respect to distributions and rights upon liquidation. The holders of the Series A preferred units were entitled to receive, when and if declared by the board, a quarterly distribution equal to the greater of $0.528125 per unit or the amount of distributions they would have received on an as converted basis, including any supplemental distributions made to common unitholders.

Financial Statement Presentation

Prior to conversion, the Series A preferred units were considered redeemable securities under GAAP due to the existence of redemption provisions upon a deemed liquidation event, which is outside MPLX’s control. Therefore, they are presented as temporary equity in the mezzanine section of the Consolidated Balance Sheets for the year end December 31, 2024. The Series A preferred units were recorded at their issuance date fair value, net of issuance costs. Income allocations increased the carrying value and declared distributions decreased the carrying value of the Series A preferred units.