Delta & Aeromexico Lose Antitrust Immunity, Scale Back Partnership

Delta and Aeromexico both belong to SkyTeam, and Delta also owns a stake in Aeromexico. Not only that, but the two airlines have antitrust immunity for transborder flights between the United States and Mexico.

Unfortunately for the airlines, that won’t be the case for long. A couple of months ago, I wrote about how US regulators tentatively announced plans to restrict their partnership going forward. There’s an update, as this order has been finalized, and will be implemented as of the beginning of 2026.

US DOT blocks Delta & Aeromexico joint venture

In July 2025, the United States Department of Transportation (DOT) announced a slate of “America First actions to combat Mexico’s abuse of bilateral aviation agreements.” As you’d expect, this was being politicized quite a bit, with Transportation Secretary Sean Duffy saying the following:

“Joe Biden and Pete Buttigieg deliberately allowed Mexico to break our bilateral aviation agreement. That ends today. Let these actions serve as a warning to any country who thinks it can take advantage of the U.S., our carriers, and our market. America First means fighting for the fundamental principle of fairness.”

While there were several aspects to this, the most significant development was the proposal that Delta and Aeromexico lose antitrust immunity for transborder flights, which they’ve had since 2016. While that was only a proposal at the time, the order has now been finalized, and this restriction will be implemented as of January 1, 2026.

To be clear, when this new restriction is implemented, the airlines can still partner — there’s nothing preventing the airlines from offering reciprocal perks for loyalty program members, for example — but they just can’t act as one entity between the United States and Mexico in terms of pricing and scheduling.

Why is the DOT blocking this close partnership? The DOT is blaming this on actions taken by the government of Mexico in relation to Mexico City Benito Juárez International Airport (MEX), which is Mexico’s largest and most important airport.

Now, it’s important to note that the DOT made a similar announcement in early 2024, under the Biden administration. However, the DOT didn’t actually follow through in finalizing the order. Now under the Trump administration, they’re actually following through on the order. I’m surprised there weren’t more negotiations or concessions.

How Mexico City Airport is at the center of this drama

The DOT has claimed that Mexico’s process of awarding slots at Mexico City Airport has long been opaque and anticompetitive, and that Aeromexico (as the largest airline there), was the primary beneficiary. The DOT claims that due to anticompetitive rules and insufficient enforcement, Aeromexico has been able to underutilize its slot portfolio, while simultaneously keeping slots out of the hands of competitors.

While the government of Mexico committed to adopting regulatory changes to improve the predictability and transparency of its slot allocation process, that hasn’t happened.

It gets even worse than that, though. More recently, the government of Mexico has banned all cargo operations from Mexico City Airport, and has also reduced capacity at the airport over the last four IATA traffic seasons, to the detriment of both current air carriers and potential new entrants.

The government has justified these flight reductions by claiming that they’re needed for the airport to undergo a significant renovation. However, the government has also conceded that no such work has taken place, yet it still won’t allow additional capacity at the airport, meaning existing airlines can’t add service, and new entrants can’t enter the market.

It sure seems to me like the primary motive of the government of Mexico is to continue pushing operations to the less desirable Mexico City Felipe Angeles International Airport (NLU). But that airport hasn’t been gaining traction in the same way the government has hoped, which is why it’s also important that competitors maintain access to the city’s main airport.

Bottom line

As of January 1, 2026, US regulators are taking away antitrust immunity from Delta and Aeromexico. This was proposed back in July, but after a public commenting period, has been finalized, so this is really happening. This is because of Mexico’s baseless restrictions at Mexico City Airport, which disproportionately help Aeromexico, while hurting other airlines.

Ultimately these kinds of close partnerships between airlines need to be renewed on an ongoing basis, and regulators can consider if they’re still good for consumers. I think the DOT is right here, in terms of the arrangement between the two carriers not necessarily being good for consumers anymore.

As I said above, this doesn’t mean that Delta and Aeromexico have to end their partnership. Rather, they just can’t coordinate schedules and fares, and will have to act as competitors in the market.

What do you make of Delta and Aeromexico losing antitrust immunity?