MPLX LP - Limited Partnership
US ˙ NYSE ˙ US55336V1008

SecurityMPLX / MPLX LP - Limited Partnership
InstitutionNorthern Trust Corp
Latest Disclosed Ownership28,953 shares
Latest Disclosed Value $ 1,652,348
Northern Trust Corp reports 9.36% increase in ownership of MPLX / MPLX LP - Limited Partnership

On May 14, 2026 - Northern Trust Corp filed a 13F-HR form disclosing ownership of 28,953 shares of MPLX LP - Limited Partnership (US:MPLX) valued at $1,652,348 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 26,476 shares of MPLX LP - Limited Partnership. This represents a change in shares of 9.36% during the quarter. The current value of the position is $1,635,265 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-14 2026-03-31 13F MPLX COM UNIT REP LTD 55336V100 28,953 2,477 9.36 1,652 16.91 0.0000
2026-02-17 2025-12-31 13F MPLX COM UNIT REP LTD 55336V100 26,476 609 2.35 1,413 9.37 0.0000
2025-11-14 2025-09-30 13F MPLX COM UNIT REP LTD 55336V100 25,867 -8,118 -23.89 1,292 -26.17 0.0000
2025-08-13 2025-06-30 13F MPLX COM UNIT REP LTD 55336V100 33,985 -282,126 -89.25 1,751 -89.66 0.0002
2025-05-13 2025-03-31 13F MPLX COM UNIT REP LTD 55336V100 316,111 279,693 768.01 16,918 871.18 0.0025
2025-02-14 2024-12-31 13F MPLX COM UNIT REP LTD 55336V100 36,418 -18,378 -33.54 1,743 -28.49 0.0002
2024-11-13 2024-09-30 13F MPLX COM 55336V100 54,796 3,339 6.49 2,436 11.18 0.0004
2024-08-14 2024-06-30 13F MPLX COM 55336V100 51,457 -9,988 -16.26 2,192 -14.18 0.0004
2024-05-14 2024-03-31 13F MPLX COM 55336V100 61,445 -1,186 -1.89 2,554 11.05 0.0004
2024-02-13 2023-12-31 13F MPLX COM 55336V100 62,631 1,111 1.81 2,300 5.07 0.0004
2023-11-13 2023-09-30 13F MPLX COM 55336V100 61,520 -2,708 -4.22 2,188 0.41 0.0004
2023-08-11 2023-06-30 13F MPLX COM 55336V100 64,228 -21,795 -25.34 2,180 -26.46 0.0004
2023-05-15 2023-03-31 13F MPLX COM 55336V100 86,023 6,098 7.63 2,963 12.92 0.0006
2023-02-13 2022-12-31 13F MPLX COM 55336V100 79,925 22,922 40.21 2,625 53.36 0.0006
2022-11-14 2022-09-30 13F MPLX COM 55336V100 57,003 -11 -0.02 1,711 2.95 0.0004
2022-08-12 2022-06-30 13F MPLX COM 55336V100 57,014 -16,763 -22.72 1,662 -32.08 0.0004
2022-05-13 2022-03-31 13F MPLX COM 55336V100 73,777 -100,184 -57.59 2,447 -52.46 0.0004
2022-02-08 2021-12-31 13F MPLX COM UNIT REP LTD 55336V100 173,961 -28,474 -14.07 5,147 -10.69 0.0008
2021-11-15 2021-09-30 13F MPLX COM UNIT REP LTD 55336V100 202,435 -92,330 -31.32 5,763 -33.97 0.0010
2021-08-13 2021-06-30 13F MPLX COM UNIT REP LTD 55336V100 294,765 -160,662 -35.28 8,728 -25.23 0.0015
2021-05-12 2021-03-31 13F MPLX COM UNIT REP LTD 55336V100 455,427 11,839 2.67 11,673 21.54 0.0022
2021-02-11 2020-12-31 13F MPLX COM UNIT REP LTD 55336V100 443,588 -22,860 -4.90 9,604 30.81 0.0019
2020-11-16 2020-09-30 13F MPLX COM UNIT REP LTD 55336V100 466,448 4,283 0.93 7,342 -8.06 0.0016
2020-08-14 2020-06-30 13F MPLX COM 55336V100 462,165 -11,895 -2.51 7,986 44.96 0.0019
2020-05-14 2020-03-31 13F MPLX COM UNIT REP LTD 55336V100 474,060 -34,036 -6.70 5,509 -57.41 0.0016
2020-02-14 2019-12-31 13F MPLX COM UNIT REP LTD 55336V100 508,096 -7,399 -1.44 12,936 -10.40 0.0029
2019-11-13 2019-09-30 13F MPLX COM 55336V100 515,495 150,345 41.17 14,438 22.82 0.0035
2019-08-13 2019-06-30 13F MPLX COM UNIT REP LTD 55336V100 365,150 -67,582 -15.62 11,755 -17.41 0.0028
2019-05-13 2019-03-31 13F MPLX COM UNIT REP LTD 55336V100 432,732 -34,997 -7.48 14,233 0.43 0.0035
2019-02-12 2018-12-31 13F MPLX COM UNIT REP LTD 55336V100 467,729 5,037 1.09 14,172 -11.68 0.0040
2018-11-14 2018-09-30 13F MPLX COM UNIT REP LTD 55336V100 462,692 76,218 19.72 16,046 21.63 0.0039
2018-09-18 2018-06-30 13F/A-1 MPLX COM UNIT REP LTD 55336V100 386,474 170,158 78.66 13,193 84.59 0.0034
2018-08-14 2018-06-30 13F MPLX COM UNIT REP LTD 55336V100 438,345 222,029 14,964
2018-05-09 2018-03-31 13F MPLX COM UNIT REP LTD 55336V100 216,316 4,866 2.30 7,147 -4.72 0.0019
2018-02-14 2017-12-31 13F MPLX COM UNIT REP LTD 55336V100 211,450 13,087 6.60 7,501 8.01 0.0019
2017-11-13 2017-09-30 13F MPLX COM UNIT REP LTD 55336V100 198,363 -56,512 -22.17 6,945 -18.42 0.0018
2017-08-11 2017-06-30 13F MPLX COM 55336V100 254,875 -68,765 -21.25 8,513 -27.10 0.0024
2017-05-12 2017-03-31 13F MPLX COM 55336V100 323,640 6,378 2.01 11,678 6.32 0.0034
2017-02-13 2016-12-31 13F MPLX COM 55336V100 317,262 101,212 46.85 10,984 50.16 0.0034
2016-11-09 2016-09-30 13F MPLX COM 55336V100 216,050 39,319 22.25 7,315 23.09 0.0023
2016-08-12 2016-06-30 13F MPLX COM UNIT REP LTD 55336V100 176,731 3,406 1.97 5,943 7.62 0.0019
2016-08-19 2016-03-31 13F/A-1 MPLX COM UNIT REP LTD 55336V100 173,325 1,258 0.73 5,522 -18.40 0.0018
2016-05-13 2016-03-31 13F Mplx COMM 55336V100 173,308 5,146
2016-02-12 2015-12-31 13F Mplx COMM 55336V100 172,067 159,858 1,309.35 6,767 1,352.15 0.0022
2015-11-12 2015-09-30 13F MPLX COM 55336V100 12,209 12,209 0.00 466 0.0002
2015-08-13 2015-06-30 13F MPLX COM 55336V100 0 -17,948 -100.00 0 -100.00
2015-05-14 2015-03-31 13F MPLX COM 55336V100 17,948 -9,028 -33.47 1,315 -33.65 0.0004
2015-02-12 2014-12-31 13F MPLX COM 55336V100 26,976 -28,746 -51.59 1,982 -39.67 0.0006
2014-11-13 2014-09-30 13F MPLX COM 55336V100 55,722 -428 -0.76 3,285 -9.30 0.0010
2014-08-14 2014-06-30 13F MPLX COM 55336V100 56,150 -12,981 -18.78 3,622 6.97 0.0011
2014-05-14 2014-03-31 13F MPLX COMM 55336V100 69,131 50,597 273.00 3,386 309.93 0.0011
2014-02-21 2013-12-31 13F/A-1 MPLX COM 55336V100 18,534 -4,872 -20.82 826 -3.17 0.0003
2014-02-12 2013-12-31 13F MPLX COM 55336V100 18,534 826
2013-11-13 2013-09-30 13F MPLX COM 55336V100 23,406 877 3.89 853 2.90 0.0003
2013-08-09 2013-06-30 13F MPLX COM 55336V100 22,529 22,529 829 0.0003
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.