Let's think higher than that. Let's just get rid of megacorporations: let's mandate that any company with more than amount of X employees should be broken down into smaller divisions, with a separate board and CEO, and make it that no one can be on more than one board at the same time.
Make X low enough, 250, and all of this would go away: no more corporatism, no more monopolies, no more special groups interests paying for government lobbying, no more abuse of power from a handful of companies...