A federal judge has blocked JetBlue Airway’s attempted purchase of Spirit Airlines.

On Tuesday, U.S. District Judge William Young blocked a planned $3.8 billion merger between JetBlue Airways and Spirit Airlines over concerns that the deal was anti-competitive and would harm consumers.

Although Spirit and JetBlue offered ample reasons that the anti-competitive harms of the proposed acquisition would be offset, Judge Young said, “evidence fails to establish that the proposed merger would not substantially lessen competition in at least some of the relevant markets.”

The merger had the potential to bolster JetBlue’s ability to compete against larger airlines for upper-income and business flyers. However, Judge Young determined the deal would eliminate competition between JetBlue and Spirit for budget flyers.

“We disagree with the U.S. District Court’s ruling,” said JetBlue and Spirit in a joint statement provided to CBS MoneyWatch. “We continue to believe that our combination is the best opportunity to increase much-needed competition and choice by bringing low fares and great service to more customers in more markets while enhancing our ability to compete with the dominant U.S. carriers.”

While the two airlines were dissatisfied with the verdict, critics of the merger saw it as a win against an already heavily consolidated industry.

The decision was an enormous triumph for consumers, travelers, and communities, according to William J. McGee, senior fellow for aviation and travel at the American Economic Liberties Project, a nonprofit advocating for corporate accountability,

“For decades, across multiple Administrations, the DOJ offered token protests and rubber-stamped airline merger after airline merger, which has resulted in the most consolidated state the industry has ever been in,” McGee told The Dallas Express.

“We now have the fewest scheduled passenger airlines that we have had since the 1910s, and the Big Four — American, Delta, Southwest, and United — control about 80% of the market. Judge Young’s ruling was a victory for airline passengers, and hopefully, it will be a critical step in restoring real competition in air travel,” he said.

Shares of Spirit Airlines (NYSE: SAVE) were hammered by the unsuccessful merger on Tuesday, with the company’s market cap falling from $1.63 billion to about $660 million by Wednesday. Overall, shares of Spirit have plunged about 60% compared to the roughly 13% decrease in JetBlue’s stock price (NASDAQ: JBLU).

Representatives for Spirit and JetBlue were not immediately available for comment.