What do futures hold in store?

This Friday, China will start trading CSI 300 index futures, allowing investors to play a derivative, either long or short, with leverage.

In a front-page editorial last week, the China Securities Journal hailed the event as a "milestone" that will create a "stabilizer" and enable the Chinese market to evolve "from prosperity to maturity".

Many people believe index futures will make the world a better place for investors. You can profit either way, the argument goes; if the market swings too far in one direction, investors will hedge, thereby reducing volatility.