Marathon Petroleum Corporation
MX ˙ BMV ˙ US56585A1025
SecurityMX:MPC / Marathon Petroleum Corporation
InstitutionBlair William & Co/il
Latest Disclosed Ownership41,132 shares
Latest Disclosed Value $ 10,043,727
Blair William & Co/il ownership in MPC / Marathon Petroleum Corporation

On May 8, 2026 - Blair William & Co/il filed a 13F-HR form disclosing ownership of 41,132 shares of Marathon Petroleum Corporation (MX:MPC) valued at $10,043,727 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 54,349 shares of Marathon Petroleum Corporation. This represents a change in shares of -24.32% during the quarter.

Blair William & Co/il has a history of taking positions in derivatives of the underlying security (MPC) in the form of stock options. The firm currently holds call options representing 0 of underlying shares valued at $0 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

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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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

MX:MPC / Marathon Petroleum Corporation Historical Put/Call Ratio
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)
2026-05-08 2026-03-31 13F MARATHON PETE COM 56585A102 41,132 -13,217 -24.32 10,044 13.63 0.0288
2026-02-17 2025-12-31 13F MARATHON PETE COM 56585A102 54,349 10,039 22.66 8,839 3.49 0.0237
2025-11-12 2025-09-30 13F MARATHON PETE COM 56585A102 44,310 -1,096 -2.41 8,540 13.23 0.0227
2025-07-24 2025-06-30 13F MARATHON PETE COM 56585A102 45,406 -4,763 -9.49 7,542 3.19 0.0209
2025-05-09 2025-03-31 13F MARATHON PETE COM 56585A102 50,169 -2,982 -5.61 7,309 -1.42 0.0220
2025-02-12 2024-12-31 13F MARATHON PETE COM 56585A102 53,151 4,908 10.17 7,415 -5.66 0.0216
2024-11-12 2024-09-30 13F MARATHON PETE COM 56585A102 48,243 -2,783 -5.45 7,859 -11.22 0.0231
2024-08-12 2024-06-30 13F MARATHON PETE COM 56585A102 51,026 -927 -1.78 8,852 -15.44 0.0273
2024-05-09 2024-03-31 13F MARATHON PETE COM 56585A102 51,953 -460 -0.88 10,469 34.64 0.0329
2024-02-12 2023-12-31 13F MARATHON PETE COM 56585A102 52,413 2,033 4.04 7,776 1.98 0.0265
2023-11-09 2023-09-30 13F MARATHON PETE COM 56585A102 50,380 -783 -1.53 7,624 27.81 0.0292
2023-08-11 2023-06-30 13F MARATHON PETE COM 56585A102 51,163 -1,513 -2.87 5,966 -16.01 0.0219
2023-05-12 2023-03-31 13F MARATHON PETE COM 56585A102 52,676 162 0.31 7,102 16.20 0.0284
2023-02-10 2022-12-31 13F MARATHON PETE COM 56585A102 52,514 -132 -0.25 6,112 16.89 0.0266
2022-11-09 2022-09-30 13F MARATHON PETE COM 56585A102 52,646 79 0.15 5,229 20.99 0.0240
2022-08-10 2022-06-30 13F MARATHON PETE COM 56585A102 52,567 -2,324 -4.23 4,322 -7.91 0.0192
2022-05-13 2022-03-31 13F MARATHON PETE COM 56585A102 54,891 -3,006 -5.19 4,693 26.67 0.0164
2022-02-14 2021-12-31 13F MARATHON PETE COM 56585A102 57,897 41,124 245.18 3,705 257.28 0.0116
2021-11-12 2021-09-30 13F MARATHON PETE COM 56585A102 16,773 962 6.08 1,037 8.59 0.0035
2021-08-12 2021-06-30 13F MARATHON PETE COM 56585A102 15,811 -3,373 -17.58 955 -6.92 0.0033
2021-05-13 2021-03-31 13F MARATHON PETE COM 56585A102 19,184 539 2.89 1,026 33.07 0.0039
2021-02-09 2020-12-31 13F MARATHON PETE COM 56585A102 18,645 -1,815 -8.87 771 28.50 0.0028
2020-11-06 2020-09-30 13F MARATHON PETE COM 56585A102 20,460 8,093 65.44 600 29.87 0.0025
2020-08-12 2020-06-30 13F MARATHON PETE COM 56585A102 12,367 -829 -6.28 462 48.08 0.0022
2020-05-11 2020-03-31 13F MARATHON PETE COM 56585A102 13,196 -33,385 -71.67 312 -88.88 0.0020
2020-02-13 2019-12-31 13F MARATHON PETE COM 56585A102 46,581 8,935 23.73 2,807 22.74 0.0144
2019-11-12 2019-09-30 13F MARATHON PETE COM 56585A102 37,646 -192 -0.51 2,287 8.18 0.0132
2019-08-13 2019-06-30 13F MARATHON PETE COM 56585A102 37,838 -9,201 -19.56 2,114 -24.90 0.0121
2019-05-14 2019-03-31 13F MARATHON PETE COM 56585A102 47,039 51 0.11 2,815 1.51 0.0172
2019-02-14 2018-12-31 13F MARATHON PETE COM 56585A102 46,988 10,091 27.35 2,773 -6.03 0.0203
2018-11-13 2018-09-30 13F MARATHON PETE COM 56585A102 36,897 6,440 21.14 2,951 38.09 0.0181
2018-08-13 2018-06-30 13F MARATHON PETE COM 56585A102 30,457 -4,065 -11.78 2,137 -15.33 0.0145
2018-05-15 2018-03-31 13F MARATHON PETE COM 56585A102 34,522 -1,135 -3.18 2,524 7.27 0.0178
2018-02-14 2017-12-31 13F MARATHON PETE COM 56585A102 35,657 89 0.25 2,353 17.94 0.0160
2017-11-13 2017-09-30 13F MARATHON PETROLEUM COM 56585A102 35,568 -1,971 -5.25 1,995 1.58 0.0150
2017-08-04 2017-06-30 13F MARATHON PETROLEUM COM 56585A102 37,539 -3,662 -8.89 1,964 -5.26 0.0147
2017-05-10 2017-03-31 13F MARATHON PETROLEUM COM 56585A102 41,201 29,596 255.03 2,073 254.97 0.0167
2017-02-14 2016-12-31 13F MARATHON PETROLEUM COM 56585A102 11,605 1,935 20.01 584 48.60 0.0052
2016-11-14 2016-09-30 13F MARATHON PETROLEUM COM 56585A102 9,670 -674 -6.52 393 0.00 0.0035
2016-08-08 2016-06-30 13F MARATHON PETROLEUM COM 56585A102 10,344 1,127 12.23 393 14.91 0.0037
2016-05-16 2016-03-31 13F MARATHON PETROLEUM COM 56585A102 9,217 -1,205 -11.56 342 -36.67 0.0032
2016-02-16 2015-12-31 13F MARATHON PETROLEUM COM 56585A102 10,422 823 8.57 540 21.62 0.0051
2015-11-12 2015-09-30 13F MARATHON PETROLEUM COM 56585A102 9,599 1,535 19.04 444 5.46 0.0038
2015-08-03 2015-06-30 13F MARATHON PETROLEUM COM 56585A102 8,064 3,808 89.47 421 -3.44 0.0006
2015-05-11 2015-03-31 13F MARATHON PETROLEUM COM 56585A102 4,256 4,256 0.00 436 0.0007
2015-02-05 2014-12-31 13F MARATHON PETROLEUM COM 56585A102 0 -4,136 -100.00 0 -100.00
2014-11-04 2014-09-30 13F MARATHON PETROLEUM COM 56585A102 4,136 769 22.84 350 19.86 0.0006
2014-05-06 2014-03-31 13F MARATHON PETROLEUM COM 56585A102 3,367 1,007 42.67 292 35.19 0.0005
2014-02-11 2013-12-31 13F MARATHON PETROLEUM COM 56585A102 2,360 2,360 216 0.0004
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2017-08-04 2017-06-30 13F MARATHON PETE CORP COM OPTION Call 0 -100.00 0 -100.00 n/a n/a n/a
2017-05-10 2017-03-31 13F MARATHON PETE CORP COM OPTION Call 1,000 51 n/a n/a n/a
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.