No it's most likely just overconfidence in the market by a few individuals. Intrade actually checked for manipulation themselves: "We checked this out for pot

No it's most likely just overconfidence in the market by a few individuals. Intrade actually checked for manipulation themselves: "We checked this out for potential manipulation - it certainly fit the pattern at first glance. However, during the period you reference above 40 individuals bought Romney shares and no individual bought more than 15% of the shares traded during that period. A look at those 40 accounts shows nothing suspicious. So we don't believe this was manipulation but more a run on Romney when the market was unusually thin." http://www.theatlantic.com/business/archive/2012/10/should-presidential-campaigns-spend-more-money-manipulating-intrade/264000/#comment-690223587 http://www.theatlantic.com/business/archive/2012/10/should-p... However, even without this spike the Intrade market was misaligned for more than 24 hours. A few of our arbitrage customers made huge amounts of money (outside our software) trading 5-10% arbs between Intrade and Matchbook. This is extremely uncommon. Disclaimer: I'm one of the developers behind sports arbitrage software RebelBetting (http://www.rebelbetting.com http://www.rebelbetting.com)