To the investors on Intrade, there was little question who came away from Wednesday night's presidential debate on top: Mitt Romney.
Intrade is a prediction market that allows investors to wager on the outcome of events. In this case: the presidential election. (Watch video: The debate in 99 seconds)
Earlier this week, the site's users placed the odds that President Obama would win re-election as high as 79%. Just before the debate began, the odds were at 74%. But in the minutes after the debate finished, the index showed Obama's numbers had fallen to 68.9%. An hour later, the odds had dropped further, to 67%. And by 10 a.m. Thursday, they were down to 66.1%.
Intrade's odds of Obama's re-election fell nearly 8 percentage points since the open of trading Thursday. That's the biggest daily drop for the Obama during this election cycle. The next biggest decline came on Aug. 20, 2011, but that was only a 2.7-point decline. That drop came two weeks after Standard & Poor's had downgraded the U.S. credit rating, prompting a sharp slide in U.S. stock prices.
The numbers may well change as more trades come in, but the figures suggest Romney improved his chances of capturing the White House. Of course, there is a long way to go, and at least two more presidential debates, before Election Day.
Intrade works by letting users swap contracts on events with a yes or no outcome. President Obama will win reelection, or he won't. A correct prediction moves the value of a contract to $10. A miss leaves you with $0.
But Intrade isn't just about betting. Its users are -- taken together -- shockingly good at correctly forecasting election results. Intrade bettors correctly picked the winner of every single state during the 2004 presidential election. In 2008, they missed two -- wrongly calling Indiana for John McCain and Missouri for Barack Obama.
And that is way, way more accurate than most single polls -- to say nothing of the predictions offered by the professional pundit class.
Related: CNN's full coverage of the debate