What Is Behind The Move In Marathon Petroleum Stock

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Marathon Petroleum (MPC) stock fell 7.4% on Tuesday, October 27, 2026, while the S&P 500 gained 0.6%. The company released no announcement, earnings report, or filing around the move. Yet every company on its peer list, including Valero Energy and Phillips 66, fell sharply during the same session. So where does Marathon Petroleum's profit come from, and how much does it swing?

Marathon Petroleum Earns Most Of Its Profit From Refining

On the August 4, 2026 call, management said the refining and marketing segment produced about $6.7 billion of Marathon Petroleum's $8.5 billion in adjusted EBITDA in the second quarter of fiscal 2026. A refiner like Marathon earns the gap between what it pays for crude oil and what it receives for gasoline, diesel, and jet fuel.

Management said the segment's gain from a year earlier came primarily from a stronger margin environment, and Marathon's reported figures highlight how much its profit swings alongside those margins. The company posted a 13.4% operating margin in the second quarter of fiscal 2026, compared with 5.6% in the same quarter a year earlier. In the first quarter, when Marathon had plant turnaround work under way, that margin was 3.0%. Management also called the refining backdrop constructive on that call, with global refining capacity out of service running about 4 million barrels a day above historical norms.

Was Marathon Petroleum Alone In Falling?

No. Valero Energy, Phillips 66, PBF Energy, HF Sinclair, and Delek US, the companies on Marathon's peer list, all fell the same session. They dropped by between 7.0% and 10.4%, with only Phillips 66 falling less than Marathon.

The wider energy sector fell far less, with the sector fund XLE losing 2.1%. This aligns Marathon's drop with its peers, not with energy stocks as a whole, and not with the market, which rose.

Where Marathon Petroleum Stock Stands Now

Marathon Petroleum had not fallen this much in a single session over the previous year. Its largest earlier fall in that time was 6.1%, on November 4, 2025.

The drop followed a long climb. The stock returned 125.9% over the twelve months to October 27, against 15.0% for the S&P 500, and 88.7% over the last six months alone. Tuesday's close of $435.98 was below the stock's highest close of the past year, $484.92 on October 14, 2026. Its lowest close in that year, $162.63, came on December 31, 2025.

At that price, you pay 0.82 times Marathon's sales over the twelve months to June 30, 2026, against 3.2 times for the S&P 500. On earnings, the gap is smaller, at 14.7 times for Marathon against 22.6 for the index.

Management said on the August call that planned maintenance in the third quarter, at a projected cost of about $290 million, would limit its ability to upgrade certain products in the Gulf Coast and MidCon regions. Marathon Petroleum is expected to report its results for the third quarter of fiscal 2026 in November 2026. Its refining and marketing adjusted EBITDA per barrel, which was $24.84 in the second quarter by management's measure, is the figure to watch in that report.

How To Act On MPC?

Not necessarily on Marathon Petroleum alone, if your goal is long-term wealth. Wealth is built by owning the companies that keep outperforming, the leaders of their industries, wherever they are. Marathon Petroleum is one. Over the five years to October 2026, its stock rose 637%, ahead of all 10 other companies in Oil & Gas Refining & Marketing, where the typical company rose 316%.

Finding companies like these takes comparison across industries and sectors, and that is what the Trefis High Quality (HQ) Portfolio does. It holds 30 quality companies in equal weight and, since its inception in September 2020, has returned more than 105%, ahead of a benchmark that combines the S&P 500, S&P Mid-cap and Russell 2000. See how we find the leaders.

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