Key Highlights

  • Marathon Petroleum finished among the eight worst performers in the S&P 500 on Friday, with no company-specific news found, a pullback after a strong Thursday rally driven by reports of Chinese refiners suspending fuel exports.
  • US diesel prices hit a record $6.52 a gallon on September 22 and averaged $6.37 on Friday, reflecting refinery damage in the Gulf and Ukrainian drone strikes on Russian refineries that tightened supply.
  • G7 nations agreed to release 100 million barrels of crude and diesel over four months, with a substantial diesel release front-loaded into the first 20 days; diesel futures fell to about $4.49 a gallon.
  • The broader market rallied on a weak jobs report, with the S&P 500 up 56.27 points to 7,722.72 and the Nasdaq-100 closing at a record, even as refiners including Marathon lagged within an energy sector that finished only slightly higher.

Marathon Petroleum (NYSE:MPC), which runs one of the biggest refining networks in the United States, has ridden this year's diesel squeeze to strong gains. On Friday, it took a breather. Shares slipped and finished among the eight worst performers in the S&P 500, behind fellow refiner Valero and just ahead of Phillips 66. No company-specific news was found. The decline looked like a giveback after a big Thursday, and it came the same day the G7 agreed to tap emergency stockpiles, though no report explicitly linked the two.

Thursday's Run-Up

On Thursday, October 1, refiners were the stars of the energy sector. Marathon Petroleum jumped and Valero climbed too, while oil major Exxon Mobil was roughly flat. Energy was the best-performing S&P 500 sector that day.

Thursday's oil rally was driven by reports that Chinese refiners were suspending fuel exports for October and by US troop deployments to the Middle East. Commentary in September had noted that four refiners had logged six straight weekly gains.

When a stock runs that hard, even a modest shift in the news can prompt traders to lock in profits.

The Diesel Crunch in Context

The real story of the oil market in 2026 is not just crude, but refined products. Refinery damage in the Gulf and Ukrainian drone strikes on Russian refineries have tightened Supply of diesel, the fuel that powers trucks, farm equipment and ships.

US diesel prices hit a record $6.52 a gallon on September 22 and averaged $6.37 on Friday. For refiners like Marathon, that squeeze has supported the margins on turning crude into diesel.

The G7 Response

On Friday, the G7, coordinated through the International Energy Agency, agreed to release 100 million barrels of crude and diesel over four months, with a substantial diesel release front-loaded into the first 20 days. Back in March, IEA members had committed 426 million barrels.

Diesel futures fell to about $4.49 a gallon. WTI crude settled at $91.11, down $1.76, while Brent ended almost unchanged at $102.25, keeping the gap between the two benchmarks around $11.

A Market Moving the Other Way

Marathon's dip stood out on a positive day. A weak September jobs report, showing just 29,000 new jobs, prompted traders to sharply cut the odds of a Federal Reserve rate hike in October. Tech stocks surged and the Nasdaq-100 closed at a record 30,807.93. The S&P 500 rose 56.27 points to 7,722.72, and the Dow added 250.40 points to 51,176.96.

The broader energy sector still ended slightly higher, but within it, refiners lagged while Brent's resilience supported others. Chevron, a Dow component, slipped.

Supply Risks Remain in Play

The key question for Marathon is how quickly the G7's diesel release reaches the market and how much it eases tightness. Officials have indicated the expected relief for consumers is 25 to 50 cents a gallon after several weeks.

Supply risks have not gone away. Refinery damage in the Gulf, attacks on Russian refineries and China's export pause all still matter. President Trump called Iran's latest ceasefire proposal not good enough, and the US is sending about 9,000 troops to the region. The Federal Reserve meets on October 27-28. Earnings season starts with PepsiCo on October 8 and Delta, a big buyer of jet fuel, on October 9.