Marathon Petroleum Corporation
MX ˙ BMV ˙ US56585A1025
SecurityMX:MPC / Marathon Petroleum Corporation
InstitutionMariner, LLC
Latest Disclosed Ownership553,551 shares
Latest Disclosed Value $ 135,227,916
Mariner, LLC reports 0.27% increase in ownership of MPC / Marathon Petroleum Corporation

On May 13, 2026 - Mariner, LLC filed a 13F-HR form disclosing ownership of 553,551 shares of Marathon Petroleum Corporation (MX:MPC) valued at $135,227,916 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 552,074 shares of Marathon Petroleum Corporation. This represents a change in shares of 0.27% during the quarter.

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)
2026-05-13 2026-03-31 13F MARATHON PETE COM 56585A102 553,551 1,477 0.27 135,228 50.61 0.1302
2026-02-13 2025-12-31 13F MARATHON PETE COM 56585A102 552,074 3,677 0.67 89,789 -15.67 0.1069
2025-11-14 2025-09-30 13F MARATHON PETE COM 56585A102 548,397 -28,540 -4.95 106,469 10.85 0.1376
2025-08-14 2025-06-30 13F MARATHON PETE COM 56585A102 576,937 -16,288 -2.75 96,051 11.94 0.1386
2025-05-15 2025-03-31 13F MARATHON PETE COM 56585A102 593,225 -27,488 -4.43 85,804 0.07 0.1428
2025-02-13 2024-12-31 13F MARATHON PETE COM 56585A102 620,713 -90,692 -12.75 85,743 -26.18 0.1440
2024-11-13 2024-09-30 13F MARATHON PETE COM 56585A102 711,405 -3,069 -0.43 116,150 -6.29 0.2061
2024-08-13 2024-06-30 13F MARATHON PETE COM 56585A102 714,474 143,674 25.17 123,947 7.77 0.2403
2024-05-15 2024-03-31 13F MARATHON PETE COM 56585A102 570,800 229,753 67.37 115,016 127.32 0.2378
2024-02-14 2023-12-31 13F MARATHON PETE COM 56585A102 341,047 29,408 9.44 50,598 7.28 0.1200
2023-11-13 2023-09-30 13F MARATHON PETE COM 56585A102 311,639 -25,455 -7.55 47,163 19.99 0.1265
2023-08-11 2023-06-30 13F MARATHON PETE COM 56585A102 337,094 -60,233 -15.16 39,305 74,060.38 0.1050
2023-05-15 2023-03-31 13F MARATHON PETE COM 56585A102 397,327 -3,742 -0.93 54 -99.89 0.1556
2023-02-14 2022-12-31 13F MARATHON PETE COM 56585A102 401,069 -140,939 -26.00 46,681 -13.29 0.1500
2022-11-10 2022-09-30 13F MARATHON PETE COM 56585A102 542,008 241,554 80.40 53,837 117.95 0.2152
2022-08-15 2022-06-30 13F MARATHON PETE COM 56585A102 300,454 1,918 0.64 24,701 -3.23 0.1014
2022-05-13 2022-03-31 13F MARATHON PETE COM 56585A102 298,536 17,632 6.28 25,525 42.00 0.0963
2022-02-14 2021-12-31 13F MARATHON PETE COM 56585A102 280,904 -4,680 -1.64 17,975 1.83 0.0760
2021-11-15 2021-09-30 13F MARATHON PETE COM 56585A102 285,584 19,367 7.27 17,652 9.74 0.0921
2021-08-24 2021-06-30 13F MARATHON PETE COM 56585A102 266,217 18,600 7.51 16,085 21.44 0.0998
2021-05-07 2021-03-31 13F MARATHON PETE COM 56585A102 247,617 -1,933 -0.77 13,245 28.33 0.0924
2021-02-16 2020-12-31 13F MARATHON PETE COM 56585A102 249,550 -410,750 -62.21 10,321 -46.72 0.0792
2020-11-13 2020-09-30 13F MARATHON PETE COM 56585A102 660,300 -6,133 -0.92 19,373 -22.23 0.1824
2020-08-14 2020-06-30 13F MARATHON PETE COM 56585A102 666,433 480,632 258.68 24,911 467.58 0.2497
2020-05-14 2020-03-31 13F MARATHON PETE COM 56585A102 185,801 100,587 118.04 4,389 -14.51 0.0548
2020-02-13 2019-12-31 13F MARATHON PETE COM 56585A102 85,214 1,709 2.05 5,134 1.20 0.0533
2019-11-13 2019-09-30 13F MARATHON PETE COM 56585A102 83,505 55,162 194.62 5,073 220.27 0.0607
2019-08-14 2019-06-30 13F MARATHON PETE COM 56585A102 28,343 -15,820 -35.82 1,584 -10.71 0.0189
2019-05-15 2019-03-31 13F MARATHON PETE COM 56585A102 44,163 18,769 73.91 1,774 18.35 0.0253
2019-02-13 2018-12-31 13F MARATHON PETE COM 56585A102 25,394 -2,866 -10.14 1,499 -33.67 0.0267
2018-11-14 2018-09-30 13F MARATHON PETE COM 56585A102 28,260 -405 -1.41 2,260 12.38 0.0581
2018-08-14 2018-06-30 13F MARATHON PETE COM 56585A102 28,665 24,187 540.13 2,011 514.98 0.0570
2018-05-15 2018-03-31 13F MARATHON PETE COM 56585A102 4,478 4,478 327 0.0117
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.