Warner Bros. shares gain $4 billion in a single day

Warner Bros. shares jumped 15% to a one-year high, adding $4 billion to its market value in a single day

The gains came after the media company announced plans to separate its ailing television business from its streaming and studio operations.

The company said it would split its business into two separate units, one that includes global television networks such as CNN and TNT, and the other that includes other streaming platforms, such as movie studios and entertainment shows.