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Why do inverse items (Buy No/Buy Yes) have probabilities that add up to >100%

I am sorry if this is a dumb question, I am new to this site, if anyone could help me understand this I would greatly appreciate it. It seems to me that "Buy Yes" and "Buy No" are the two sides of a particular market - with "Sell No" and "Sell Yes" being equal to the two options, respectively. For instance, it would make sense to me that if the market price for a particular "Buy Yes" is $.90, then the "Buy No" market price should be $.10, correct? Why is this not the case? What am I missing here?

Not a dumb question! The "Buy Yes" and "Sell No" sides add up to 100%, as do the "Buy No" and "Sell Yes" sides. Basically, those are the two sides to each share. Let's say I buy 100 "No" shares, then later decide that I'm on the wrong side and want to buy "Yes" shares. If I am selling "No" shares to then buy "Yes", I sell "No" at 10c and buy "Yes" at 90c, since those are saying the same thing: "Yes" is correct, "No" is not. Put another way, since both "Sell No" and "Buy Yes" mean the same thing, they add up to a full market share of 100%.

Buying and selling the opposite side isn't really relevant, though. People who disagree and believe that "Buy No" is the right answer don't really care whether I buy "Yes" or not - they believe the opposite. Their market isn't influenced by the "Yes" buys.

It's a bit convoluted, but I hope that makes sense!

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helpful, thanks, and this 'quirk' is what I find interesting about this Casino....let's be honest, this, and the stock market are just variations on the dollar game.  Kudos for making this a nice diversion, even if some-as in Casinos- are making bank and take it seriously.  My takeaway is being able to gauge the mood of the wonks and the analysts and the number crunchers, all in a single glance!

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Your logic is right, but you just have the two mixed up. BuyYes =  SellNo and BuyNo = SellYes.

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