Banks do make money by making speculative bets with their own funds on whether the dollar, say, will rise or fall against the German mark.

Within these townships many had made speculative bets on future prosperity.

Metallgesellschaft almost went bankrupt after losing an estimated $1.3 billion on speculative bets in oil future markets.

But "it's a pretty speculative bet," he said, noting that the technology "is going to see a lot of conflicting pressures moving forward."

When their speculative bet proved wrong, they had to buy back the securities quickly to limit their losses.

Efforts to fix the bank failed and the bank struggled through the end of the 1970s, suffering from highly speculative bets on interest rates.

Like many investors, these Indonesian concerns made speculative bets in 1993 that interest rates would continue to fall.

But they can also be used as a substitute for direct investments to make speculative bets on the performance of a particular market.

When large, speculative short-sale bets accumulate against a stock or other financial asset, the price can be driven down.

It could still continue to grow and thrive from there, and a speculative bet to that effect might pay off handsomely.