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