I read recently that corporate taxes used to be a lot higher on large conglomerated companies, which used to deter monopolization somewhat. Under this automatic-stake idea, it'd be interesting if the government's stake in corporations increased as they got larger? Companies try to avoid this and so don't combine so much?

Of course once the government does have a large stake in the largest monopoly-like companies, it's immensely motivated to keep them large. Hmm. This idea isn't good.