Marathon Petroleum Corporation
MX ˙ BMV ˙ US56585A1025
SecurityMX:MPC / Marathon Petroleum Corporation
InstitutionFlagship Harbor Advisors, Llc
Latest Disclosed Ownership4,186 shares
Latest Disclosed Value $ 1,022,014
Flagship Harbor Advisors, Llc reports 2.50% increase in ownership of MPC / Marathon Petroleum Corporation

On April 28, 2026 - Flagship Harbor Advisors, Llc filed a 13F-HR form disclosing ownership of 4,186 shares of Marathon Petroleum Corporation (MX:MPC) valued at $1,022,014 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 21, 2026 disclosing 4,084 shares of Marathon Petroleum Corporation. This represents a change in shares of 2.50% 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)
2026-04-28 2026-03-31 13F MARATHON PETE COM 56585A102 4,186 102 2.50 1,022 53.92 0.0449
2026-01-21 2025-12-31 13F MARATHON PETROLEUM Common Stock 56585A102 4,084 -1,459 -26.32 664 -37.83 0.0313
2025-11-05 2025-09-30 13F MARATHON PETE COM 56585A102 5,543 -19 -0.34 1,068 15.71 0.0465
2025-08-04 2025-06-30 13F MARATHON PETE COM 56585A102 5,562 -75 -1.33 924 12.42 0.0438
2025-04-22 2025-03-31 13F MARATHON PETE COM 56585A102 5,637 -78 -1.36 821 3.01 0.0432
2025-01-21 2024-12-31 13F MARATHON PETE COM 56585A102 5,715 -660 -10.35 797 -23.22 0.0419
2024-10-21 2024-09-30 13F MARATHON PETE COM 56585A102 6,375 -793 -11.06 1,039 -16.49 0.0570
2025-12-02 2024-06-30 13F MARATHON PETE COM 56585A102 7,168 2,610 57.26 1,244 35.40 0.0747
2024-04-16 2024-03-31 13F MARATHON PETE COM 56585A102 4,558 46 1.02 918 37.22 0.0590
2024-01-10 2023-12-31 13F MARATHON PETE COM 56585A102 4,512 151 3.46 669 1.36 0.0487
2023-10-17 2023-09-30 13F MARATHON PETE COM 56585A102 4,361 303 7.47 660 39.53 0.0549
2023-07-11 2023-06-30 13F MARATHON PETE COM 56585A102 4,058 1,086 36.54 473 18.25 0.0391
2023-04-12 2023-03-31 13F MARATHON PETE COM 56585A102 2,972 672 29.22 401 49.81 0.0377
2023-01-13 2022-12-31 13F MARATHON PETE COM 56585A102 2,300 36 1.59 268 18.67 0.0274
2022-10-13 2022-09-30 13F MARATHON PETE COM 56585A102 2,264 -2,047 -47.48 225 -36.44 0.0261
2022-07-13 2022-06-30 13F MARATHON PETE COM 56585A102 4,311 108 2.57 354 -1.39 0.0398
2022-04-13 2022-03-31 13F MARATHON PETE COM 56585A102 4,203 -111 -2.57 359 30.07 0.0346
2022-02-17 2021-12-31 13F/A-1 MARATHON PETE COM 56585A102 4,314 718 19.97 276 27.19 0.0261
2022-02-10 2021-12-31 13F MARATHON PETE COM 56585A102 4,314 718 276 0.0261
2021-11-01 2021-09-30 13F MARATHON PETE COM 56585A102 3,596 0 0.00 217 0.00 0.0233
2021-07-26 2021-06-30 13F MARATHON PETE COM 56585A102 3,596 3,596 217 0.0233
2021-02-08 2020-12-31 13F MARATHON PETROLEUM Common Stock 56585A102 0 -11,685 -100.00 0 -100.00
2020-10-13 2020-09-30 13F MARATHON PETROLEUM Common Stock 56585A102 11,685 -4,575 -28.14 342 -43.66 0.0462
2020-07-31 2020-06-30 13F MARATHON PETROLEUM Common Stock 56585A102 16,260 8,391 106.63 607 226.34 0.0891
2020-05-12 2020-03-31 13F MARATHON PETROLEUM Common Stock 56585A102 7,869 6,102 345.33 186 75.47 0.0372
2020-02-14 2019-12-31 13F MARATHON PETROLEUM Common Stock 56585A102 1,767 5 0.28 106 -0.93 0.0186
2019-10-22 2019-09-30 13F MARATHON PETROLEUM Common Stock 56585A102 1,762 -208 -10.56 107 -2.73 0.0210
2019-07-22 2019-06-30 13F MARATHON PETROLEUM Common Stock 56585A102 1,970 -353 -15.20 110 -20.86 0.0228
2019-04-15 2019-03-31 13F MARATHON PETROLEUM Common Stock 56585A102 2,323 10 0.43 139 2.21 0.0286
2019-01-26 2018-12-31 13F MARATHON PETROLEUM COM 56585A102 2,313 813 54.20 136 9.68 0.0331
2018-11-05 2018-09-30 13F MARATHON PETROLEUM Common Stock 56585A102 1,500 101 7.22 124 26.53 0.0230
2018-08-14 2018-06-30 13F MARATHON PETROLEUM Common Stock 56585A102 1,399 1,399 98 0.0196
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.