v3.26.1
Debt
 3 Months Ended
Mar. 31, 2026
Debt Disclosure [Abstract]  
Debt Debt
MPLX’s outstanding borrowings consist of the following:
(In millions)March 31,
2026		December 31,
2025
MPLX LP:
Fixed rate senior notes$25,969 $25,969 
Consolidated subsidiaries:
ANDX31 31 
Finance lease obligations6 6 
Total26,006 26,006 
Unamortized debt issuance costs(185)(174)
Unamortized discount(187)(179)
Amounts due within one year(1,251)(1,502)
Total long-term debt due after one year$24,383 $24,151 
Credit Agreement
MPLX’s credit agreement (the “MPLX Credit Agreement”) provides for a $2.0 billion unsecured revolving credit facility and letter of credit issuing capacity under the facility of up to $150 million. Letter of credit issuing capacity is included in, not in addition to, the $2.0 billion borrowing capacity. Borrowings under the MPLX Credit Agreement bear interest, at MPLX’s election, at either the Adjusted Term SOFR or the Alternate Base Rate, both as defined in the MPLX Credit Agreement, plus an applicable margin.
On April 7, 2026, MPLX entered into a new revolving credit facility to replace the previously existing MPLX Credit Agreement, which was scheduled to expire July 2027. The new MPLX revolving credit facility is for a five-year term which will expire April 2031. MPLX’s total capacity under the new revolving credit facility agreement increased from $2.0 billion to $2.5 billion and includes sub-facilities for swing-line loans of up to $150 million and letters of credit of up to $150 million.
At March 31, 2026, MPLX had no outstanding borrowings and less than $1 million in letters of credit outstanding under this facility, resulting in total availability of approximately $2.0 billion or approximately 100 percent of the borrowing capacity.
Fixed Rate Senior Notes
MPLX’s senior notes, including those issued by consolidated subsidiaries, consist of various series of senior notes maturing between 2027 and 2058 with interest rates ranging from 2.650 percent to 6.200 percent. Interest on each series of notes is payable semi-annually in arrears on various dates depending on the series of the notes.
On February 12, 2026, MPLX issued $1 billion aggregate principal amount of 5.300 percent senior notes due 2036 (the “2036 Senior Notes”) and $500 million aggregate principal amount of 6.100 percent senior notes due 2056 (the “2056 Senior Notes”) in an underwritten public offering. The 2036 Senior Notes were offered at a price to the public of 99.678 percent of par, with interest payable semi-annually in arrears, commencing on October 1, 2026. The 2056 Senior Notes were offered at a price to the public of 98.453 percent of par, with interest payable semi-annually in arrears, commencing on October 1, 2026.
In March 2026, MPLX used the proceeds from the 2036 Senior Notes and the 2056 Senior Notes to repay all of MPLX’s outstanding $1.5 billion aggregate principal amount of 1.750 percent senior notes at maturity.