In the trading game, there are very few things that move the broad market in a predictable direction. Simple correlation and causality get very, very hazy. It's

In the trading game, there are very few things that move the broad market in a predictable direction. Simple correlation and causality get very, very hazy. It's not a simple matter of: * get data a little early * go long on the index * profit! A trader could execute all possible best-practices, and the numbers go the 'wrong' way. Or they go the 'right' way for a while, but then turn around as other traders cash out. Regardless, there's no guaranteed profit just because you have paid for early access. The presence of risk-taking traders on all different time scales in secondary markets means that there's liquidity and accurate price-formation at a range of different time scales. At the very shortest time-scales, all customers are already against each other - it's the nature of a very liquid market, where A's gain is B's loss and vice versa. But all this churning activity means that if you want to cash out your Apple stock, there's going to be a buyer right there on the other side, at all times. Without a deep reserve of risk traders willing to take the other side of every trade, liquidity is lost and capital is less likely to be attracted to the public markets.