A federal judge on Tuesday blocked JetBlue Airways’ proposed $3.8 billion acquisition of budget carrier Spirit Airlines, agreeing with the Justice Department that the deal would hurt the availability of low-cost air travel tickets.

U.S. District Judge William Young wrote that the proposed merger "does violence to the core principle of antitrust law: to protect the United States’ markets – and its market participants – from anticompetitive harm."

Spirit’s stock plunged on the news, falling more than 51% during trading Tuesday afternoon. Dow Jones Market Data group noted that Spirit’s stock neared all-time lows in the wake of the ruling and experienced its largest percentage decrease on record.

JetBlue and Spirit can appeal the judge’s ruling if they still wish to pursue the merger.

This is a developing story. Please check back for updates.

Reuters contributed to this report.