has estimated that its ticket prices will increase by 30 percent if Spirit is no longer a competitor. came to this conclusion after an internal analysis, . The U.S. Department of Justice cited these findings on the first day of a federal antitrust trial attempting to block of Spirit Airlines.

JetBlue has taken the stance that the merger will allow the carrier to challenge the four largest airlines in the United States: , , and . JetBlue attorney Ryan Shores claimed at trial that the Big Four control 80 percent of the domestic market, a figure that doesn’t align with data from the U.S. Department of Transportation. , the Big Four have a 67.7 market share, still a strong majority.

Shores argued that the federal government allowed previous mergers that allowed the Big 4 to establish market dominance, like United’s 2010 merger with Continental Airlines. However, two wrongs don’t make a right. A JetBlue-Spirit merger would so clearly hurt airline passengers that even itself realized that.

attorney Arianna Markel stated that JetBlue internal analysis discovered that the merger could cost passengers $1 billion per year. Markel said, “JetBlue is counting on the fact that eliminating Spirit and the competition Spirit provides will allow JetBlue to raise fares. That is real harm to real people.”

Throughout this antitrust trial, will portray itself as a minnow trying to take on mammoths, but a merger with Spirit will likely create another monster in the process. No matter what your opinion about Spirit Airlines is, losing the ultra-low-cost carrier from the marketplace will do far more harm than good.