ExxonMobil and Chevron both reported third-quarter profits on Friday that beat analyst estimates by wide margins, as their refineries ran at full capacity to take advantage of diesel prices driven up by attacks on fuel-making plants in Russia and the Middle East. Exxon's profit doubled to $15.4 billion, or $3.72 a share, from $7.5 billion, or $1.76 a share, a year earlier, while Chevron's net income rose nearly 200% to $9.9 billion, or $5.06 a share, from $3.5 billion, or $1.82 a share.

The results capped a second consecutive banner quarter for the largest Western oil companies. Reuters reported that the effective closure of the Strait of Hormuz and attacks on refineries in Saudi Arabia and Russia have knocked out fuel-making capacity, and that Shell, TotalEnergies and BP also beat third-quarter profit estimates this week, with BP reaching a record. For Exxon, the shift is structural: the company is now earning more from refining than from exploration and drilling for the first time in at least six years, according to Reuters.

The diesel price behind the numbers

US diesel stood at a national average of $6.32 a gallon on Friday, an increase of more than 70% compared with the same period last year, according to AAA figures cited by CNBC. Prices reached a record high in September. Importers have increasingly turned to US Gulf Coast refineries for diesel as global capacity has shrunk, which is why American plants are the ones setting records.

"Refining capacity is very tight today," Exxon chief executive Darren Woods told CNBC. "Frankly, diesel is the key crunch point here because it is so critical to economic growth with very inelastic demand." Chevron chief executive Mike Wirth described the same conditions more briefly, saying the system was under stress and that the environment remained fairly fragile.

Where the profit came from

Chevron's refining division generated $4.9 billion in earnings, up from $1.1 billion a year earlier, a rise of more than 300%. Its oil and gas production earned $5.7 billion, up 70% from $3.3 billion. The downstream result is the unusual part: refining is normally the smaller, more cyclical business, and this quarter it approached the upstream segment.

Exxon reported revenue of $113.2 billion against analyst expectations of $103.1 billion, and adjusted earnings of $4.23 a share against a forecast of $4.08. Chevron reported revenue of $67.8 billion against $61.6 billion expected, and adjusted earnings of $5.28 a share against $4.89 expected. Both stocks touched all-time highs on Friday, with Chevron up nearly 2% and Exxon more than 1% higher.

Why the shortages may not ease quickly

Reuters reported that the supply disruption began in March after the United States and Israel attacked Iran, and that attacks on refineries have continued since. Repairing damaged refining capacity is slower than restoring crude production, because the equipment is specialised and the skills are concentrated. That lag is what turns a crude-price move into a diesel-price move.

Exxon is investing more in its refineries, including at its Baytown complex in Texas, and expects distillate production in the United States to grow by another 100,000 barrels a day through those investments, chief financial officer Neil Hansen told Reuters. The company has also leaned on its trading team to route supplies to where they are needed. Those are incremental additions against a disruption measured in millions of barrels a day of lost capacity.

Where the lost capacity sits

The disruption has more than one source. CNBC reported that Ukraine, Iran and Houthi militants have attacked refineries in Russia and the Middle East, reducing global capacity by millions of barrels per day, and that importers have turned to US Gulf Coast refineries for diesel as a result. That is why the record is being set in Texas and Louisiana rather than in the regions where the damage happened.

The same dynamic explains the shape of the beats. Analysts polled by LSEG expected Chevron to earn $4.89 a share and Exxon $4.08; the companies reported $5.28 and $4.23. Revenue also beat on both lines. Reuters described the quarter as the second straight banner period for Big Oil, with downstream earnings at Chevron reaching their highest level in at least six years.

The politics of wartime profit

The quarter is politically awkward. President Donald Trump said in August that Chevron and Exxon "were making too much money based on a shortage", according to CNBC. High profits at the largest oil companies during a war that has raised fuel costs for drivers invite scrutiny, and the two chief executives used their interviews to describe constraints rather than gains.

For readers, the numbers to separate are the profit and the price. The profit is a company result for one quarter; the price is what households and hauliers pay at the pump, and it rose more than 70% year over year. Both statements can be true at once, and the tension between them is the story.

What to watch

Three things would change the picture: whether attacked refineries return to service, whether diesel prices hold above $6 a gallon into the winter heating season, and whether governments respond with measures aimed at fuel exports or margins. None of those is settled by one earnings report.

Related coverage on this site includes Microsoft's cloud growth and Alphabet's AI cash burn, DoorDash's $17 billion purchase of Instacart and the final week of the Senate map. The first explains where technology capital is going; the second shows consolidation in consumer services; the third is the political backdrop against which fuel prices will be debated.