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The US airline sector is caught between two forces pulling in opposite directions. Oil prices are falling fast, giving stocks a short-term lift. But the industry's structural ceiling on mergers, on fares, and on long-term growth hasn't moved.
Brent crude fell as much as 7.4% in early Monday trading after a pause in US-Iran military hostilities. Delta Air Lines, United Airlines, and American Airlines each jumped on the news.
The US Global Jets ETF had already fallen 9.4% in July through Friday, so the relief was welcome but it didn't erase the month's damage.
Jet fuel is one of the airline industry's largest expenses. When crude falls sharply, airlines' cost outlook improves almost immediately in theory. But the physical picture is more complicated.
The Strait of Hormuz remains largely closed to commercial tanker traffic. Only 15 vessels transited the strait daily as of mid-July, against a pre-crisis baseline of 88 per day.
Jet fuel pricing lags crude by weeks or months because refinery contracts and inventories adjust more slowly than futures markets.
The International Air Transport Association projected jet fuel to average $152 per barrel for full-year 2026, which is 68.8% above the 2025 average, and that forecast hasn't been revised downward.
Traders repriced airline stocks on the oil drop, but travelers shouldn't expect ticket prices to follow. Average domestic fares rose 26.5% year over year through June, the second consecutive month at that level, even as an earlier ceasefire framework sent Brent crude down roughly 20% in a single month.
Four carriers control ~73% of domestic US passenger traffic, according to Jefferies. When all four face the same fuel shock and none has an incentive to cut fares and lose market share, prices hold even as costs retreat.
"Do not watch for a plunge in airfares like what's happening in gasoline prices."
Michael Boyd, Aviation Consultant
Delta grew capacity just 1% in the second quarter but revenue grew 14%. Its fuel bill hit $4.41B, the highest in company history, yet it still posted $1.4B in adjusted pretax profit because fare increases more than offset the fuel shock. United raised the floor of its full-year earnings guidance for the same reason.
The closure of Spirit Airlines, which ceased all operations in May after rising fuel costs made its ultra-low-cost model untenable, removed one of the few structural forces that had previously pushed legacy carriers toward cheaper fares on leisure routes.
The merger narrative grabbed headlines over the weekend. United CEO Scott Kirby approached Delta's CEO Ed Bastian last year about combining the two carriers. Those talks didn't progress. Kirby later approached American Airlines earlier this year and was rejected outright.
The failed attempts highlight a real problem for the sector. United and Delta together accounted for over 90% of the industry's profits last year, but industry officials have long believed a merger between those two would be blocked on antitrust grounds.
A judge blocked JetBlue Airways from acquiring Spirit in early 2024 after the Justice Department sued. Spirit subsequently collapsed anyway.
Kirby said in May that United won't participate in industry consolidation in the foreseeable future without a willing partner. That leaves organic growth as the only path, and the industry's largest carriers are already dominant.
The JETS ETF recovered from pandemic-era losses in June for the first time since 2018, briefly outpacing the S&P 500's year-to-date gain. But since the end of 2019, JETS has gained only ~4.7% while the S&P 500 is up 128% over the same period.
Demand remains genuinely strong. American Express reported that airline spending on its network rose 10% year over year in the second quarter, and US consumer travel spending grew 13%. That demand signal tells carriers there's no financial pressure to discount.
Oil is the single biggest lever for airline stocks, mergers are blocked, and fare pricing power is holding. A sustained drop in crude, not just a single morning's move, is what would structurally shift the sector's earnings picture.
Until the Strait of Hormuz reopens and jet fuel inventories rebuild, one day's geopolitical optimism is noise, not signal.
