Unions may not be the ideal solution for economists and capitalists, but they are one of the best ways to control executive compensation. At least that is the argument presented by Rafael Gomez and Konstantinos Tzioumis of the London School of Economics. A study conducted by the two found that union presence lowered CEO compensation by 10 percent, and the number rose when it was a CEO whose pay was in the top 10 percent.

The compensation is kept in check through the collective bargaining process that acts as a counterbalance - that is, when executives get a raise, the union sees it as a sign that the company is healthy and they deserve a raise. Also, Wall Street tends not to prefer unionized companies and therefore, lower stock prices mean less value for stock options granted to the CEO.