vertically integrated company

I was told that vertically integrated company is quite common today. Before the turn of 20th century, however, this is a strange model.
More and more companies are looking to earn the profits usually earned by outside companies (their suppliers or distributiors). M&A news bear testimony to this treand.
The DuPont company is the America's first large scale "vertically integrated" company. They have pointed the way back in 1900's. For a business to succeed, we have to look at this model. We cannot rely solely on supplier who doesn't want to give us good price.