That would be somewhat OK, IMHO. The power of big companies comes from the fact that they can throw money around. Breaking them up would limit it, and make these flows publicly visible.

A $10b company is pocket change to the beomouths that run the world.

Sure $10b seems like a lot to you and me, but to split Apple, Microsoft, Google to just $10b would require hundreds of different companies to form from their split. To go to $1b companies would make that thousands of companies.

You could split apple into 3000 companies and still need to split further. The CEO would be able to spend less than 1 minute a week on each company.

If that really is a problem we can just still count it as a single company for the tax office. Or make it illegal for companies to own other companies. That would even encourage competition and break down monopolies! All things capitalism thinks are good things.