Prediction markets:  These are speculative markets fashioned with the intention of making predictions. Assets which are produced possess an ultimate cash worth bound to a specific event (for example who will win the next election) or situation (such as total sales next quarter). The present market prices can then be explained as forecasts of the likelihood of the event or estimated value of the situation. Prediction markets are consequently planned as betting exchanges, without any kind of compromise for the bookmaker. People who purchase low and sell high are rewarded for improving the market prediction, whereas those who purchase high and sell low are punished for degrading the market prediction. Evidence so far proposes that prediction markets are at least as accurate as other institutions predicting same events with a similar pool of participants. Many prediction markets are open to the public. Betfair is the world's biggest prediction exchange, with around $28 billion traded in 2007. Intrade is a for-profit company with a large range of contracts not including sports. Iowa Electronic Markets is an academic market examining elections where positions are limited to $500. Trade Sports are prediction markets for sporting events.