United Airlines (UAL.US) secretly negotiated with Delta Air Lines (DAL.US) last year to create a "super airline," but the century-defining merger plan was ultimately halted due to antitrust concerns

According to a report on July 26 citing sources from English Financial News, United Airlines (UAL.US) CEO Scott Kirby personally called Delta Air Lines (DAL.US) CEO Ed Bastian in 2025 to explore the possibility of a merger between the two companies. If realized, this concept would create the world’s largest airline, with a market value close to $100 billion and control over about 50% of the U.S. air travel market. However, after an initial due diligence process, Delta’s management decided not to proceed further, and the two parties never entered formal negotiations.

A Multi-Billion Dollar Merger Concept: The Powerhouse Alliance of “Dual Oligopolists”

United Airlines and Delta Air Lines are the second and third largest airlines in the U.S., respectively, accounting for over 90% of the U.S. aviation industry’s profits in 2025. Based on their market values at the time, Delta Air Lines was valued at around $56 billion and United Airlines at about $38 billion, bringing the combined entity's scale close to $100 billion. In 2024, the two companies’ combined revenue was about $120 billion.

For United Airlines, Delta’s appeal is not just its size—Delta has long been regarded as the industry benchmark for profitability, premium customer experience, and operational reliability. Kirby has repeatedly praised Delta’s strategy of focusing on attracting high-yield passengers rather than competing on price, a philosophy that has deeply influenced United’s recent transformation. The merger would allow United to access Delta’s lucrative markets in New York and Boston, as well as its joint venture resources across the Atlantic (including Air France-KLM and Virgin Atlantic).

The “Iron Curtain” of Antitrust: Why the Deal Was Doomed from the Start

However, anyone familiar with the regulatory landscape of the U.S. aviation industry could foresee the outcome. Over the past two decades, the industry has consolidated from ten major airlines into just four—United, Delta, American Airlines, and Southwest Airlines—together controlling about 80% of the domestic market. The Department of Justice has taken an increasingly cautious stance toward further consolidation among major carriers.

Sources noted that a merger between United and Delta would trigger the toughest antitrust review since the DOJ successfully blocked JetBlue’s acquisition of Spirit Airlines. Regulatory hurdles include the possible forced divestment of slots at congested airports like Newark Liberty International and LaGuardia. Any formal merger proposal would require approval from the DOJ’s Antitrust Division and the Department of Transportation, a process that could take 12 to 18 months.

It is precisely these nearly insurmountable regulatory barriers that convinced both sides the deal was “unrealistic”; initial discussions never progressed to formal negotiations on price or structure.

Unquenched M&A Ambitions: “Two-Pronged Probe” from Delta to American Airlines

The revelation of talks with Delta exposes Kirby’s broader ambitions for industry consolidation. According to reports, after reaching out to Delta, Kirby also privately suggested to then-President Trump a merger between United and American Airlines (AAL.US). However, American Airlines CEO Robert Isom rejected the proposal outright, criticizing it as “anti-competitive.”

This “two-pronged probe” indicates that despite major regulatory obstacles, United’s management continues to evaluate the potential for reshaping competition through large-scale mergers and acquisitions. U.S. Secretary of Transportation Sean Duffy stated in April this year that there is “still room for mergers” in the U.S. airline industry, implying the regulatory environment may be more lenient than under previous administrations. Nevertheless, antitrust experts point out that even with a more relaxed regulatory stance, approval for a merger between the two largest U.S. airlines is highly unlikely.

Industry Implications: Willingness for Integration Remains, but Regulatory Ceiling Is Clear

After being successively rejected by Delta and American Airlines, Kirby publicly stated in June that United would not pursue industry consolidation in the foreseeable future. At the International Air Transport Association’s annual meeting, he candidly told the media, “I think consolidation is unlikely for United. That doesn’t mean we won’t continue to buy assets in the market, but the probability of consolidation is low.”

However, the disclosure of United’s outreach to Delta demonstrates that the desire for consolidation among U.S. airlines persists. With the four major carriers controlling about 80% of the domestic market, major hubs have extremely limited room for growth through organic expansion. Smaller players like JetBlue and Alaska Airlines are seeking growth through acquisitions and partnerships.

For investors, this report highlights the ongoing interest from major U.S. airlines in consolidation, despite increasing regulatory difficulty for large-scale deals. Any form of merger between United and Delta would face intense antitrust scrutiny, but the fundamental drivers of industry consolidation—scale effects, hub control, and cost synergies—have not disappeared. Should the regulatory environment shift even marginally, bold ideas like these may resurface.