Calamos Advisors LLC reports 1.90% increase in ownership of MPC / Marathon Petroleum Corporation

Marathon Petroleum Corporation

MX ˙ BMV ˙ US56585A1025

Security	MX:MPC / Marathon Petroleum Corporation
Institution	Calamos Advisors LLC
Latest Disclosed Ownership	319,159 shares
Latest Disclosed Value	$ 77,932,244

On May 4, 2026 - Calamos Advisors LLC filed a 13F-HR form disclosing ownership of 319,159 shares of Marathon Petroleum Corporation (MX:MPC) valued at $77,932,244 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 29, 2026 disclosing 313,204 shares of Marathon Petroleum Corporation. This represents a change in shares of 1.90% 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	Reported Shares	ΔShares	ΔShares (%)	Reported Value (x1000)	ΔValue (%)	Alloc (%)
2026-05-04	2026-03-31	13F	MARATHON PETE	COM	56585A102	319,159	5,955	1.90	77,932	53.00	0.2749
2026-01-29	2025-12-31	13F	MARATHON PETE	COM	56585A102	313,204	-23,002	-6.84	50,936	-21.40	0.1913
2025-10-20	2025-09-30	13F	MARATHON PETE	COM	56585A102	336,206	974	0.29	64,800	16.37	0.2393
2025-08-08	2025-06-30	13F	MARATHON PETE	COM	56585A102	335,232	59,238	21.46	55,685	38.49	0.2192
2025-04-29	2025-03-31	13F	MARATHON PETE	COM	56585A102	275,994	2,208	0.81	40,210	5.28	0.1750
2025-01-24	2024-12-31	13F	MARATHON PETE	COM	56585A102	273,786	626	0.23	38,193	-14.17	0.1597
2024-11-07	2024-09-30	13F	MARATHON PETE	COM	56585A102	273,160	32,423	13.47	44,500	6.55	0.1924
2024-07-25	2024-06-30	13F	MARATHON PETE	COM	56585A102	240,737	-5,041	-2.05	41,763	-15.67	0.1855
2024-05-08	2024-03-31	13F	MARATHON PETE	COM	56585A102	245,778	-127,166	-34.10	49,524	-10.49	0.2346
2024-01-31	2023-12-31	13F	MARATHON PETE	COM	56585A102	372,944	-3,218	-0.86	55,330	-2.81	0.2684
2023-10-26	2023-09-30	13F	MARATHON PETE	COM	56585A102	376,162	533	0.14	56,928	29.98	0.2958
2023-07-28	2023-06-30	13F	MARATHON PETE	COM	56585A102	375,629	-122,369	-24.57	43,798	-34.77	0.2167
2023-05-04	2023-03-31	13F	MARATHON PETE	COM	56585A102	497,998	-65,977	-11.70	67,145	2.29	0.3279
2023-01-26	2022-12-31	13F	MARATHON PETE	COM	56585A102	563,975	-74,835	-11.71	65,641	3.45	0.3079
2022-10-24	2022-09-30	13F	MARATHON PETE	COM	56585A102	638,810	-58,335	-8.37	63,453	10.72	0.2902
2022-08-01	2022-06-30	13F	MARATHON PETE	COM	56585A102	697,145	123,494	21.53	57,312	16.85	0.2472
2022-05-03	2022-03-31	13F	MARATHON PETE	COM	56585A102	573,651	62,987	12.33	49,047	50.10	0.1841
2022-02-01	2021-12-31	13F	MARATHON PETE	COM	56585A102	510,664	-38,522	-7.01	32,677	-3.74	0.1222
2021-10-26	2021-09-30	13F	MARATHON PETE	COM	56585A102	549,186	39,540	7.76	33,945	10.24	0.1483
2021-07-22	2021-06-30	13F	MARATHON PETE	COM	56585A102	509,646	92,876	22.28	30,793	38.13	0.1407
2021-04-12	2021-03-31	13F	MARATHON PETE	COM	56585A102	416,770	-47,446	-10.22	22,293	16.11	0.1216
2021-01-27	2020-12-31	13F	MARATHON PETE	COM	56585A102	464,216	-155,006	-25.03	19,200	5.68	0.1114
2020-10-26	2020-09-30	13F	MARATHON PETE	COM	56585A102	619,222	-96,512	-13.48	18,168	-32.09	0.1169
2020-07-27	2020-06-30	13F	MARATHON PETE	COM	56585A102	715,734	-430,122	-37.54	26,754	-1.15	0.1891
2020-04-28	2020-03-31	13F	MARATHON PETE	COM	56585A102	1,145,856	575,690	100.97	27,065	-21.21	0.2124
2020-01-15	2019-12-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	570,166	113,637	24.89	34,352	23.86	0.1699
2019-10-21	2019-09-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	456,529	17,756	4.05	27,734	13.11	0.1511
2019-08-07	2019-06-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	438,773	-34,975	-7.38	24,519	-13.53	0.1361
2019-04-12	2019-03-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	473,748	-675	-0.14	28,354	1.28	0.1769
2019-01-24	2018-12-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	474,423	21,961	4.85	27,996	-22.63	0.1848
2018-10-22	2018-09-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	452,462	186,241	69.96	36,183	93.72	0.1990
2018-07-17	2018-06-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	266,221	-19,391	-6.79	18,678	-10.55	0.1142
2018-04-13	2018-03-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	285,612	4,498	1.60	20,882	12.58	0.1359
2018-02-13	2017-12-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	281,114	-2,598	-0.92	18,548	16.57	0.0945
2017-10-25	2017-09-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	283,712	200,027	239.02	15,911	263.35	0.1230
2017-08-09	2017-06-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	83,685	-7,346	-8.07	4,379	-4.83	0.0324
2017-04-20	2017-03-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	91,031	-407	-0.45	4,601	-0.07	0.0362
2017-02-06	2016-12-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	91,438	-19,230	-17.38	4,604	2.49	0.0366
2016-11-14	2016-09-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	110,668	209	0.19	4,492	7.13	0.0321
2016-07-26	2016-06-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	110,459	41	0.04	4,193	2.14	0.0294
2016-04-25	2016-03-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	110,418	6,657	6.42	4,105	-23.68	0.0272
2016-02-05	2015-12-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	103,761	2,200	2.17	5,379	14.33	0.0342
2015-11-10	2015-09-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	101,561	3,689	3.77	4,705	-8.11	0.0324
2015-08-14	2015-06-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	97,872	46,375	90.05	5,120	-2.90	0.0316
2015-05-13	2015-03-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	51,497	30	0.06	5,273	13.52	0.0331
2015-02-13	2014-12-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	51,467	267	0.52	4,645	7.15	0.0307
2014-11-14	2014-09-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	51,200	0	0.00	4,335	8.46	0.0289
2014-08-14	2014-06-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	51,200	23,700	86.18	3,997	66.96	0.0253
2014-05-16	2014-03-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	27,500	0	0.00	2,394	-5.11	0.0153
2014-02-14	2013-12-31	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	27,500	0	0.00	2,523	42.62	0.0160
2013-11-14	2013-09-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	27,500	0	0.00	1,769	-9.47	0.0111
2013-08-12	2013-06-30	13F	MARATHON PETROLEUM	COMMON STOCK	56585A102	27,500	27,500		1,954		0.0128

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.