Subsidiaries would count as part of the company, so that wouldn't be viable a loop-hole and separate companies colluding to set prices is already illegal so the

Subsidiaries would count as part of the company, so that wouldn't be viable a loop-hole and separate companies colluding to set prices is already illegal so they couldn't do that either. The IP leaseback thing may require other rules but would only really affect some market areas. But in those cases other metrics could be used like numbers of products sold or active users or whatever is appropriate. Company size and market share may be hard to define, but people are capable of accomplishing difficult things, when they really want to.