You can't really encourage the creation of big business.
I see venture capitalism as encouraging the formation of big businesses all the time. There's a lot of good ideas that require too much to start off the small.
Google, mentioned early as a small business that became big, started off with a $100,000 angel investment. The Home Depot was also mentioned and, while it was planned and started by a small group of entrepreneurs, it was financed largely by an investment bank.
But venture capital is fairly common when it comes to starting companies in general, no?
My point was rather that whether a company becomes big or not depends mostly on how successful they are, not on government policies.
(Unless you do a China and simply outlaw a bunch of smaller companies)