Comment by georgeecollins

But they don't have all the same owners. If I own company 2/3 of company A and it is worth $0, and I own 2/3 of company B I can't force company B to buy company A for $1. The company B shareholders will be upset and could sue.

Maybe this is a good deal for shareholders of SpaceX and xAI. But then maybe it isn't a good deal for one set of shareholders. I have no idea, but I would love to be a shareholder in SpaceX and would not want to be a shareholer in xAI. Totally depends on the price of course.