A trader rigged a weather bet by heating the single sensor that decided the outcome, a bad sign for trust in fast-growing prediction markets.

• Weather contracts settled off one temperature sensor at an airport, an easy single point of failure.
• A bettor held a hair dryer next to that sensor to push the reading up and win his bet.
• The payoff was small money, but the method shows people will tamper with the physical world to move a market.
• Prediction markets built on thin, unguarded data are wide open to this kind of gaming.

Outlook: Expect pressure on prediction market operators to settle contracts using multiple data sources rather than a single sensor.