Marathon Petroleum Corporation

The full register, from 13F filings

The Register tab above is hand research: a dozen holders, each traced to the filing it came from. This asks the same question of the whole market for the quarter ended 31-mar-2026, where 1,865 managers reported a position. Broad where the research is deep, and shallow in the ways a 13F always is.

Built from 13F filings, which report US listed, long, US custodied positions only. A register from this source is a floor rather than a level: a holder's true position can be far larger, as BlackRock's ASML stake shows at 1.28m shares in a 13F against 26.3m in its 13G/A. Holdings held through derivatives, outside US custody, or below a manager's reporting obligation do not appear. Where a holder is marked as a family, its total sums several separate filing entities and describes something no single filing describes; the constituent entities and their share counts are listed so the total can be checked. That roll-up can legitimately exceed the family's own Schedule 13G, because a 13G is filed by one legal entity: Vanguard reports Alphabet through ten advisory entities, and The Vanguard Group Inc itself reported zero after its January 2026 disaggregation.

What a reader needs to know to read these numbers

• MPC consolidates MPLX LP (NYSE: MPLX) in its financial statements because it controls MPLX through ownership of MPLX's general partner, MPLX GP LLC, and holds a large majority (approximately 64 percent as of 30 June 2026 and as of 31 December 2025) of MPLX's outstanding common units. This is recorded as a holding, sized in MPLX COMMON UNITS (not MPC shares, not a share class of MPC), because MPLX is a separately listed, separately SEC-registered entity. The public float of MPLX common units (roughly 36 percent) shows up on MPC's own consolidated balance sheet as 'Noncontrolling interests' ($6,643 million at 30 June 2026, $6,772 million at 31 December 2025); that noncontrolling-interest balance belongs to MPLX's public unitholders, is the OPPOSITE direction of an MPC holding, and is deliberately excluded from the holdings list.
• MPC's FY2025 Form 10-K contains a fully itemized equity method investments note (not a single combined balance) giving both an ownership percentage and a carrying value for each named investee at 31 December 2025 and 31 December 2024, split across Refining & Marketing, Midstream (further split between entities held through MPLX and entities MPC retains directly), and Renewable Diesel. The 13 named investees recorded as holdings here sum to exactly $5,471 million of the note's $6,795 million total equity-method balance at 31 December 2025, which itself ties to the 'Equity method investments' line on MPC's consolidated balance sheet.
• The remaining $1,324 million of the 31 December 2025 equity-method balance is reported only inside three combined 'Other' lines (Midstream/MPLX Other $1,123 million, Midstream/MPC-Retained Other $113 million, Renewable Diesel Other $88 million) that are not broken out by counterparty in the note fetched; per the brief's rule for combined balances, none of that $1,324 million is assigned to any named holding.
• Two prior equity-method positions were excluded because they are no longer equity-method holdings as of the most recent filings: MPC sold its 49.9 percent interest in The Andersons Marathon Holdings LLC (TAMH) on 31 July 2025 for $427 million cash and derecognized a $173 million carrying value; and MPLX purchased the remaining 55 percent of BANGL, LLC on 1 July 2025 for $703 million cash plus a contingent earnout, taking MPLX's ownership to 100 percent, so BANGL is now a wholly owned, consolidated subsidiary rather than a holding.
• MPC's Q2 2026 Form 10-Q reports a higher combined equity method investments balance of $7,197 million at 30 June 2026 (versus $6,795 million at 31 December 2025), but the 10-Q text fetched does not repeat the itemized per-investee breakdown that appears in the 10-K; the individual holdings above are therefore dated 31 December 2025 (the most recent date at which a per-investee split was found), not restated to the newer combined total.
• MPC has a single class of common stock; no dual-class structure and no founder control block. Maryann T. Mannen, President, CEO and Chairman, beneficially owns approximately 0.034 percent of MPC common stock; the full 18-person current directors and executive officers group owns approximately 0.166 percent in total.
• Register coverage: the 7 institutional 13F rows sum to 105,164,302 shares, approximately 37.5 percent of the 280,824,763 shares outstanding used as the denominator throughout this file (self-gate check, excluding the insider rows which use the proxy's own 295,184,752 denominator and excluding the aggregate/member insider rows per the overlap rule).
• Vanguard filed Form 13F-NT (notice, no holdings) under CIK 0000102909 for the quarters ended 31 March 2026 and 30 June 2026, so its most recent Form 13F-HR under that CIK is for the quarter ended 31 December 2025 (38,291,917 shares); that is the figure used in the register, consistent with the project's Vanguard-substitution rule following its January 2026 reporting reorganisation into multiple filers.
• The DEF 14A proxy's own 'Security Ownership of Certain Beneficial Owners' (5%-owner) table, as of 1 February 2026, reports different and generally staler figures sourced to each holder's own Schedule 13G/A: Vanguard 38,865,857 shares (13.2%, from a 13G/A filed 29 July 2025 as of 30 June 2025); State Street 25,127,390 shares (8.5%, from a 13G/A filed 30 January 2024 as of 31 December 2023, over two years stale); BlackRock 21,060,653 shares (7.1%, from a 13G/A filed 23 April 2025 as of 31 March 2025). The register above uses each manager's own, more current Form 13F-HR instead and does not separately reproduce these proxy-table rows, to avoid duplicate, conflicting entries for the same three holders. The Vanguard figures in particular disagree (38,291,917 per 13F vs 38,865,857 per the stale 13G/A); both are recorded here rather than one overwriting the other.
• No fresh Schedule 13D or 13G filed directly against MPC's own CIK (0001510295) was found for 2025 or 2026; the EDGAR filing-history feed for 'SC 13' forms under this CIK shows the most recent entries dated 10 September 2024 (13G/A) and 10 May 2024 (13D/A), both pre-dating this file's time window, so no activist or sovereign strategic holder is recorded in the register beyond the 13F-based institutions and the proxy-based insiders.
• 13F share and value figures use each filer's own titleOfClass 'COM'/'COMMON' lines under CUSIP 56585A102 (issuer name abbreviated by filers as 'MARATHON PETE CORP'); JPMorgan's filing additionally reports one 30,000-unit 'MARATHON PETE CORP OPTION' derivative line under CUSIP 56585A902, which is excluded from JPMorgan's share and value totals as a derivative, not an equity position.