In more extreme cases, look at John D. Rockefeller's Standard Oil. Rockefeller used to be the wealthiest person in the world (according to some, if you inflation adjust his money, he may have been the wealthiest person in the last 200 years). His company was broken into parts in order to promote competition.
John D. Rockefeller actually ended up being a lot richer because the courts broke up Standard Oil[1]. He went from having a controlling stake in the most powerful company in oil, to having a controlling stake in most of the powerful companies in the whole oil industry (ExxonMobil, Chevron, BP, Shell). I just wanted to clarify that point because the order in which your statement was crafted kind of made it seem like the courts broke up his wealth when they actually expanded it.
1.Rockefeller, who had rarely sold shares, held over 25% of Standard’s stock at the time of the breakup. He, as well as all stockholders, received proportionate shares in each of the 34 companies...The companies’ combined net worth rose fivefold and Rockefeller’s personal wealth jumped to $900,000,000.http://en.wikipedia.org/wiki/John_D._Rockefeller