Quote from Profitaker:
Need a bit more meet on the bones maverick. What are you on about ?
Take a single die and roll it. You have six numbers that can come up. Let's say you could buy a bet and sell a bet on that die. In other words if I bet $3 and the die came up 6, I would earn $3. If I sold a bet for $4 and a 2 came up, I would make $2. Well, if you calculate the fair value of this bet, you would know that the fair value, or expected return is 3.5. Now obviously you can't roll a 3.5, but that is the number you should bet to breakeven over a large number of rolls. If I was to buy a bet, I would want to bet less then 3.5 and if I were to sell a bet, I would want to sell it for more then 3.5. Doing so over a large number of rolls, would guarantee me a profit. However, if I bet 3.5, no matter if I am the buyer or the seller, I can expect to only breakeven over the long run minus any commissions.
BTW, this is the first thing they ask you in an interview if you ever apply to work for a market making firm trading options. Very basic probability theory.
So what I am saying about a 20 delta option is that over any single event, it's possible for the buyer to make a large return and the seller could suffer a large loss. However, over a large number of turns, eventually the buy and seller of that 20 delta option will have equal returns, which are zero, minus commissions. This of course is assuming neither the buyer or the seller made any further adjustments to the trades. I hope I have made this more clear.
BTW, the expected value of the dice role is (6+5+4+3+2+1)/6=3.5