According to sources familiar with the matter reported by media on July 26, United Airlines (UAL.US) CEO Scott Kirby personally called Delta Air Lines (DAL.US) CEO Ed Bastian in 2025 to explore the possibility of merging the two companies. If realized, this vision would create the world's largest airline, with a market value of nearly $100 billion and controlling approximately 50% of the U.S. air travel market. However, Delta's management decided to abandon the plan after conducting preliminary due diligence, and the two sides never entered formal negotiations.
Billion-Dollar Merger Vision: A "Duopoly" of Profits Joining Forces
United Airlines and Delta Air Lines are the second and third largest U.S. airlines, respectively, contributing more than 90% of the U.S. airline industry's profits in 2025. Based on market capitalization at the time, Delta was valued at approximately $56 billion and United at about $38 billion, with the combined entity approaching $100 billion. The two companies had combined revenues of approximately $120 billion in 2024.
For United, Delta's appeal extended beyond scale—Delta has long been regarded as an industry benchmark for profitability, premium customer experience, and operational reliability. Kirby has publicly praised Delta's strategy of focusing on attracting high-yield passengers rather than competing on price, a philosophy that has deeply influenced United's transformation in recent years. A merger would give United access to Delta's profitable markets in New York and Boston, as well as its transatlantic joint venture partners, including Air France-KLM and Virgin Atlantic.
Antitrust "Iron Curtain": Why the Deal Was Doomed from the Start
However, anyone familiar with the U.S. airline industry's regulatory environment could foresee the outcome of such a transaction. Over the past two decades, the U.S. airline industry has consolidated from 10 major carriers to four—United, Delta, American Airlines, and Southwest Airlines—collectively controlling about 80% of the domestic market. The Department of Justice has become increasingly cautious about further consolidation among major carriers.
Sources indicated that a merger between United and Delta would trigger the most stringent antitrust scrutiny since the DOJ successfully blocked JetBlue's acquisition of Spirit Airlines. Regulatory hurdles include the potential forced divestiture of flight slots at congested airports such as Newark Liberty International Airport and LaGuardia Airport. 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 was these nearly insurmountable regulatory barriers that led both sides to deem the deal "impractical," with initial discussions never reaching the stage of formal negotiations over price or structure.
Unfulfilled Merger Ambitions: A "Two-Pronged" Approach from Delta to American
The disclosure of the Delta approach reveals Kirby's broader ambitions for industry consolidation. Reports indicate that after contacting Delta, Kirby separately proposed to then-President Donald Trump a merger between United and American Airlines (AAL.US). However, American Airlines CEO Robert Isom directly rejected the proposal, criticizing it as "anti-competitive."
This "two-pronged" approach suggests that, despite significant regulatory headwinds, United's management is actively evaluating the potential for reshaping the competitive landscape through large-scale mergers. U.S. Transportation Secretary Sean Duffy said in April that the U.S. airline industry "still has room for consolidation," hinting at a more lenient regulatory environment than under the previous administration. However, antitrust experts caution that even with a more accommodating stance, it is unlikely that regulators would approve a merger between two of the largest U.S. airlines.
Industry Implications: Consolidation Ambitions Remain, but Regulatory Ceiling Is Clear
After being rebuffed by both Delta and American, Kirby stated publicly in June that United would not pursue industry consolidation in the foreseeable future. Speaking at the International Air Transport Association Annual General Meeting, he told media: "I don't think consolidation is likely for United. That doesn't mean we won't continue to buy assets in the market, but the probability of consolidation is very low."
Nevertheless, the disclosure of the Delta approach indicates that the appetite for consolidation within the U.S. airline industry persists. The dominance of the "Big Four" carriers, controlling about 80% of the domestic market, leaves limited room for organic growth at major hubs. Smaller players like JetBlue and Alaska Airlines are seeking growth through acquisitions and partnerships.
For investors, this report highlights the ongoing interest of major U.S. airlines in consolidation, even as regulatory barriers make large-scale mergers increasingly difficult. Any form of merger between United and Delta would face severe antitrust scrutiny, but the underlying drivers of industry consolidation—economies of scale, hub control, and cost synergies—remain intact. When the regulatory environment shows marginal shifts, similar bold ideas could resurface.
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