What is going on with intrade? The percentages add up to over 100 in most states and nationally

[BzaDem]

Does that usually happen? I keep clicking states and so many of them add up to 105-110%. Obviously not a big deal, and I'm not saying it means anything about Obama's chances; I'm just curious what that means in terms of prediction markets.

[tkmorris]

1. I dunno, but I believe you are seeing the "vigorish"

That is to say, the inherent percentage built in by betting sites, bookies, etc that ensures that they see a profit no matter who wins.

[central scrutinizer]

2. It's not a zero sum game - it's gambling

If the odds are long enough, people will lay money on a horse that they really don't think has much chance of winning. And Intrade simply responds to the money coming in and out.