AT&T just re-merged after the break-up, so it’s a bad example.
See the diagram: https://www.theverge.com/2016/10/24/13389592/att-time-warner...
See the diagram: https://www.theverge.com/2016/10/24/13389592/att-time-warner...
I don’t doubt the break-ups are effective in the short term, but the long-term behavior in this case seems to be less affected.