A federal judge in Massachusetts has squashed JetBlue’s attempted acquisition of Spirit Airlines, citing the court’s fear of continuing a trend that began in the 21st century: the consolidation of the airline industry into an “oligopoly” due to a series of mergers such as the proposed JetBlue-Spirit deal.

The U.S. Department of Justice and several state attorneys general filed a complaint in March to stop the merger after a deal totaling $3.8 billion was struck, which would have created the fifth-largest airline in the nation.