But the most basic premise of a fair market is that it's not "stacked" at all -- that everyone has an equal chance to react to market moves and price changes.

For example, a business cannot possibly get one cent more than the purchasers of their stock offer in the marketplace, and because of transaction fees, somewhat less. And an investor has the same experience -- he can't possibly get more than the market value of his shares on the day of sale.

Brokerage houses are in competition to offer the lowest transaction costs and the most reliable environment for trading. That competition reduces transaction prices for everyone.

Conclusion? Not stacked in general. Insider trading is a crime, betting against your own customers is a crime, and these things happen, but they're prosecuted.