https://www.commondreams.org/news/paramount-merger-settlemen...
Hypothetically California could have done something to prevent the merger. Then they [Paramount] leave California, as threatened, and then complete the merger.
The Federal government is the entity which needs to be the enforcer of antitrust. Otherwise major companies like these WILL pick and and leave the state blocking them. It's a 111 billion deal - this is worth moving states for the parties involved.
Here's the issue: nothing stops them from leaving the state anyway after the deal is made. The concessions lack any weight. California folded potentially for nothing.