Delta Air Lines makes money by flying people and cargo between more than 300 destinations on six continents. Passengers pay for tickets, and Delta collects more when they choose premium seats like Delta One or First Class over a standard main cabin seat. Beyond ticket sales, Delta runs a loyalty program called SkyMiles, sells miles to American Express for its co-branded credit card, repairs aircraft for other airlines through its Delta TechOps business, operates a fuel refinery near Philadelphia called Monroe Energy, and packages vacations through Delta Vacations. That is a lot of moving parts for what most people think of as simply an airline. The diagram below traces where the money goes.

Five years of financial data tell a clear story of recovery and then steady growth. In 2021, revenue was $29.9 billion, still depressed from the effects of the pandemic on travel. By 2022 revenue had jumped to $50.6 billion as passengers came back in large numbers. Growth continued through 2023 at $58.0 billion, 2024 at $61.6 billion, and 2025 at $63.4 billion. That is more than a doubling of revenue in four years.

Cash flow from operations also improved every single year. It went from $3.3 billion in 2021 to $8.3 billion in 2025. That cash is not just sitting still. Delta used it to pay down debt aggressively. Net debt fell from $17.2 billion in 2021 to $8.2 billion in 2025, nearly cut in half in four years. All three major credit rating agencies now rate Delta as investment grade, which means lenders see it as a lower-risk borrower than before.

Not everything in the numbers is straightforward positive. Operating income in 2025 was $5.8 billion, which was actually $173 million lower than in 2024. Revenue grew 3%, but operating expenses also grew 3%, largely because salaries rose as Delta implemented pay increases for employees including a 4% raise for pilots on January 1, 2025, and a 4% raise for eligible staff on June 1, 2025. The business is generating more cash, but expenses are rising at roughly the same pace as revenue, which means the profit margin is not expanding right now.

One of the most important things to understand about Delta is that the SkyMiles loyalty program is not just a perk for frequent flyers. It is a significant revenue engine. American Express paid Delta $8.2 billion in 2025 for the right to give its credit card customers SkyMiles miles. Delta expects that number to grow to $10 billion. This revenue is more predictable than ticket sales, because it comes in monthly based on how much people spend on their credit cards, not on whether planes are full.

Premium travel is another important trend to watch. In 2025, revenue from premium products like Delta One and First Class was $22.1 billion, up 7% from 2024. Main cabin revenue was $23.4 billion, down 5% from 2024. That gap is meaningful. More customers are choosing to pay more for better seats, and Delta has been adding premium seats to new aircraft as it refreshes its fleet. The company noted that industry-wide supply of main cabin seats exceeded demand in an uncertain economic environment, while premium demand stayed strong.

Delta's risks are specific and worth naming clearly. Fuel cost is the biggest operational expense after salaries. Fuel was 17% of total operating expenses in 2025. The problem is that passengers book tickets weeks or months in advance, locking in a price. If jet fuel prices spike after those tickets are sold, Delta absorbs the difference. Owning the Monroe refinery near Philadelphia is meant to reduce that risk, but the refinery brings its own problems. An unexpected mechanical breakdown, a storm, or a strike could cut off fuel supply to Delta's New York operations.

Technology is a real risk too, not just a talking point. In July 2024, a faulty software update from a company called CrowdStrike caused a global IT outage that hit Delta hard. Roughly 7,000 flights were cancelled over five days, costing Delta approximately $380 million in lost revenue and around $170 million in extra costs. Delta relies heavily on the Delta app, electronic ticketing, cloud systems, and artificial intelligence tools for things like baggage routing and gate decisions. Any serious tech failure can cascade quickly into cancellations.

Finally, Delta is rated investment grade by all three major agencies, but the debt load is still substantial. The principal amount of debt and finance leases was $14.1 billion at the end of 2025. Delta has committed to roughly $15.4 billion in future aircraft purchases as of December 31, 2025, plus expected capital spending of approximately $5.5 billion in 2026 alone. The company is simultaneously paying down old debt and taking on new commitments for new planes. That balancing act requires steady, strong cash flow.