A federal judge has issued an injunction blocking the merger between television station operators Nexstar Media Group and Tegna Inc., ordering the companies to immediately cease integration efforts after the Federal Communications Commission allowed them to exceed broadcast ownership limits.

The ruling requires the defendants to "immediately cease" all actions to integrate and consolidate their operations, effectively halting the merger process that had been moving forward despite regulatory concerns about market concentration.

The case centers on federal broadcast ownership rules that limit how many television stations a single company can control in local markets. The FCC had previously allowed the companies to proceed with their merger plans despite these ownership thresholds being exceeded.

Nexstar, one of the largest television station operators in the United States, had been working to acquire Tegna's portfolio of broadcast television stations across multiple markets. The combined entity would have created significant market concentration in several regions.

The injunction represents a significant setback for the proposed merger, which would have reshaped the landscape of local television ownership. The companies will need to address the court's concerns about ownership limits before they can proceed with any integration activities.

Both Nexstar and Tegna have not immediately responded to requests for comment regarding the court's decision and their plans moving forward.