Delta Just Cut Its Profit Forecast Over Fuel. Here's Who Wins When Diesel Breaks.
Delta expects to pay about 18% more per gallon this quarter and cut its 2026 forecast by more than $1 a share. Oil bounced back above $104 and diesel is near its record. The shortage is in refining, and it decides who pays and who collects.
Delta expects to pay about 18% more per gallon of fuel this quarter than last. Oil slipped under $100 for a day last week, then jumped back above $104. Diesel eased but is still near its record. The reason is a refining bottleneck, and it decides which side of your portfolio pays and which side collects.
HeyTheo Research · Monday, October 12, 2026
Quick Read
Delta reported on Friday, Oct 9. It cut its 2026 earnings forecast to $5.10 to $5.60 a share, from $6.50 to $7.50, and expects about $6 billion of extra fuel cost this year.
Delta paid $3.61 a gallon for fuel in the third quarter. It assumes about $4.25 for the fourth, roughly 18% more.
Brent crude dipped to about $97 on Tue, Oct 6, then jumped above $104 on Thu, Oct 8 on tanker attacks near the Strait of Hormuz and Hurricane Isaias. US diesel was $6.20 a gallon on Oct 5, about 5% below its late-September record.
The shortage is in refining, not crude. If it eases, money moves from companies that make fuel to companies that burn it. Delta just showed both sides of that trade.
What Delta told investors on Friday
Airlines are the clearest window into fuel costs, because fuel is their second-largest bill and they report it in detail. Delta reports first.
Line | Third quarter | What changed |
|---|---|---|
Fuel price per gallon | $3.61 | About $4.25 assumed for the fourth quarter |
Fuel expense | $4.1 billion | Up 62% from a year earlier |
Revenue (adjusted) | $17.6 billion | Up 16%. About 20% growth guided for the fourth quarter |
Earnings per share (adjusted) | $1.72 | Analysts had expected about $1.85 |
2026 earnings guidance | $5.10 to $5.60 | Cut from $6.50 to $7.50 |
Source: Delta Air Lines third-quarter 2026 results and earnings call, Oct 9. Analyst estimate from pre-report previews. The 18% rise in fuel price is a desk calculation.
Two things are true at once. Demand is strong: Delta said it is "not discounting fares," its fourth quarter is already more than 60% booked, and revenue is growing at its fastest pace in years. And fuel is eating the gain. Fuel expense rose about four times faster than revenue.
Delta also owns a refinery, which softens the blow. It counts about 40 cents a gallon of refinery benefit in its fourth-quarter number. Most airlines, truckers and shippers have no such cushion.
Why fuel got dearer even when oil got cheaper
Last week showed the problem in miniature.
Marker | Level | Date |
|---|---|---|
Brent crude | About $97 a barrel | Tue, Oct 6 |
Brent crude | Above $104 a barrel | Thu, Oct 8 |
US diesel, national average | $6.20 a gallon, down 18 cents in a week | Mon, Oct 5 |
US diesel, record | About $6.53 a gallon | Late September |
US Strategic Petroleum Reserve | 283 million barrels, lowest since 1982 | Early October |
Source: ICE, US Energy Information Administration, AAA, US Department of Energy
Crude has bounced around with the headlines. Diesel has drifted down slowly from its record but stays far above anything seen before this year, because diesel does not come out of the ground. It comes out of a refinery.
Think of a bakery. There can be plenty of wheat, but if half the ovens are off, bread stays expensive.
More than 7 million barrels a day of fuel supply from the Middle East and Russia is offline. Refineries worldwide are processing about 4.2 million barrels a day less than a year ago. US diesel stocks are at their lowest for this time of year since government records began in 1982.
The gap between what a refiner pays for crude and what it sells fuel for is called the crack spread. It hit record levels this summer. That is where the profit has gone: Valero, Marathon Petroleum and Phillips 66 have been among the best-performing large stocks of 2026, trading near all-time highs.
Research cue · try it in HeyTheo
Ask Theo for the bull case, bear case and what to watch on a refiner you follow, and add: "what happens to earnings if the gap between crude and diesel prices narrows by a third?" After a run this long, the bear case deserves equal time. Open HeyTheo
Two shocks in one week
Crude's bounce on Thursday had two causes.
The first was shipping. Attacks on tankers in and around the Strait of Hormuz reached their highest level since the conflict began, and tanker traffic fell to its lowest since late July.
The second was weather. Hurricane Isaias forced operators to shut in about a quarter of US Gulf of Mexico oil output before it made landfall on the Alabama and northwest Florida coast on Friday night. Close to 500,000 barrels a day of refining sat near its path, including Chevron's Pascagoula plant in Mississippi. The storm's track stayed east of the large Louisiana refineries.
Gulf Coast refineries hold just over half of US refining capacity, and they were running near 95% before the storm. There is almost no spare capacity to cover an outage. Whether any refinery near the track stays offline this week is the first thing to check.
What the reserve release can and cannot do
On Oct 2 the G7 agreed to release up to 100 million barrels from emergency reserves over about four months, roughly half diesel and half crude.
Flow | Million barrels a day |
|---|---|
Fuel supply offline (Middle East and Russia) | More than 7.0 |
Refinery processing below a year ago | 4.2 |
G7 release, averaged over four months | About 0.83 |
Source: International Energy Agency, industry estimates. The release rate is a desk calculation: 100 million barrels over about 120 days.
The release is real relief, and it probably helped diesel ease last week. But it covers a fraction of what is missing, and markets were disappointed to learn the barrels come from volumes already pledged earlier this year. What ends the squeeze is refineries coming back, and industry executives have said tight conditions could last into 2027.
Who gains and who gives back
Because the shortage sits in refining, a fall in diesel would not help or hurt "energy" as one block. It would move money between groups.
Group | How fuel reaches them | What to check |
|---|---|---|
Airlines | Jet fuel comes from the same part of the barrel as diesel | Fuel price assumption for next quarter |
Truckers, railroads, parcel carriers | Diesel is a top running cost. Surcharges lag the price | Margins in the quarter after fuel turns |
Retailers and food makers | Freight is built into the cost of every product | Commentary on shipping costs |
Refiners | They earn the gap between crude and fuel | The crack spread |
Oil producers | They sell crude, which swings with headlines | Brent, not diesel |
Source: HeyTheo Research
Delta is the useful case study. It raised fares and still lost about a quarter of its expected annual profit to fuel. A company with less pricing power, such as a trucker on fixed contracts, has even less room. That is why fuel users have the most to gain when diesel finally breaks, and why their reports this month are worth reading for one line: the fuel price they assume next.
Research cue · try it in HeyTheo
Build two baskets: fuel users (airlines, truckers, cruise lines) and fuel makers (refiners). Track one against the other. If users start to outpace makers, the market is pricing in cheaper fuel before the pump shows it. Open HeyTheo
Why this reaches every portfolio
Fuel is in the price of nearly everything, which makes diesel an inflation story.
September inflation data arrives on Wednesday, Oct 14, at 8:30 AM ET. As we laid out in our note on jobs, bonds and the Nasdaq, that number decides whether long-term interest rates keep climbing. A sustained fall in diesel is one of the few things that could cool inflation without the job market weakening further.
The same morning, Bank of America and Morgan Stanley report. Banks see fuel costs too, in whether truckers and households keep paying their loans. Our bank earnings preview covers what to read in those reports.
Research cue · try it in HeyTheo
Open the money-flow view and check where money moved within energy and transportation last week. Then set a trigger on any refiner you hold: "tell me if this stock falls more than 5% in a day." A stock near its record can move fast when its margin story changes. Open HeyTheo
Research it yourself: rules HeyTheo tracks
Fuel users vs fuel makers. Two baskets tracked against each other. The gap between them is a market-based read on where diesel is heading.
Diesel trigger. Flags when the national average diesel price falls more than 10% from its record. From about $6.53, that line is about $5.88. It is already about 5% below.
Fuel-cost trigger. During earnings, flags any holding that changes its fuel price assumption for the next quarter.
Ask Theo. Try: "Which of my holdings have the largest fuel bills?" or "Give me the bear case for refiners if diesel inventories start to rebuild."
Check the rule behind any trigger before acting on it. You trade through your own broker; HeyTheo helps you decide.
The Receipt at the Pump
Crude oil gets the headlines, and last week it went from under $100 to above $104 and back toward $105. The receipt at the truck stop moved far less, and it is closer to the real economy.
Until refineries catch up, the price that matters is the gap between crude and fuel. It explains why refiners trade near records, why Delta lost a quarter of its expected profit despite record revenue, and why a 100-million-barrel release can help for weeks without fixing anything for good.
When that gap closes, money moves from the companies that make fuel to the companies that burn it. The useful work now is knowing which side each of your holdings sits on.
Start your own first pass. Download HeyTheo, add the airlines, carriers and refiners you follow, and run the three cues above before Wednesday's inflation report. Get the app
Sources
Delta Air Lines, US Energy Information Administration, AAA, International Energy Agency, US Department of Energy, ICE, Kpler, Reuters, Bloomberg, CNN, OilPrice.com, Insurance Business, Fortune, Live and Let's Fly, The Motley Fool, Bureau of Labor Statistics
Disclaimer
Disclaimer: HeyTheo is a research and education platform, not an investment adviser or broker-dealer. Nothing here is advice to buy, sell, or hold any security. You trade through your own broker; HeyTheo helps you decide. Backtested results are hypothetical and do not guarantee future returns. References to governments, officials, or policies are for market context only and are not political endorsements. All investing involves risk, including loss of principal. Data is as of the dates noted.