I don't have a problem with big business. Dense urban populations are more efficient than scattered rural ones and big conglomerate farms and distributors are more efficient than small ones. That's carbon efficient too. If we want a sustainable economic structure without genocidal elements, big is beautiful.
As long as the workers get their fair share of the profits, the companies pay their taxes, and non-profit worker-owned competitors get a fair shot at setting up, and smaller local shops are supported to make sure that all sections of the population have access to good value food, where's the problem.
We have a maximum wage and a tax system which covers all forms of income generation and wealth accrual. There won't be any loopholes, come the revolution.