The problem was that the two markets acted on each other; as the futures price fell, so did the cash value of shares, forcing institutions to sell more futures and so on.
An increasingly heated takeover battle for the Chicago Board of Trade (CBOT), one of the world's leading futures exchanges, has sent its market value soaring.
In some futures markets, she says, the amount of money in play at any one time can be "35 or 40 times" the value of the entire stocks of that commodity available in the world.