For a market to function properly, information pertinent to traded value has to flow freely. The more you stifle that, the more rigged the market. Essentially, you sustain a monopoly that way.
Of course, people in possession of such "insider information" believe themselves in the right to profit from it. But that perspective is obviously biased and reveals a fundamental conflict between public good and private ownership. From the public perspective, the market works best when monopolies are dissolved quickly.
