As a modern example: look at luxotica for an example of a monopoly. They own large shares of the manufacturing and retail for eyeglasses, and they charge exorbitant prices.

They own Oakley, Ray-Ban, LensCrafters, Pearle Vision and Sunglass Hut. They also operate Sears Optical and Target Optical.

They also produce eyewear under license for names such as Coach, Anne Klein, Bulgari, Prada, Polo, Versace, Ralph Lauren, and Tiffany.

http://online.wsj.com/article/SB1000142405274870451890457536...

Making manufacturers divest of retail operations is a way to break up their monopoly.