I was wondering something about market makers... Lets say for example that you think that RUT is not going to be below 490 at the august expiration. Its very conservative I know but its just as an example... Well then you could do one of these 2 things: 1) You buy a call spread 480/490 (buy the 480 and sell the 490) for a net debit of 9.75$. So lets say its 100 contracts: Total debit and max risk: 9.75*100*100= 97 500$ Max Gain: 0.25*100*100= 2500$. 2) A short put spread 480/490 (buy the 480 and sell the 490) for a net credit of 0.25$. Max gain and net credit: 0.25*100*100= 2500$ Max loss: (10-0.25)*100*100= 97 500$ As you can see, same strike of 490 for max profit, same max loss, same max gain. Nonewithstanding the carrying cost since its 10 days and the 10 days risk-free rate is minimal and I think it could be discarded (read the next paragraph). In a case like this, would you say that you have better chances of getting filled on either one of them or they would be the same? IMO the market maker would prefer filling the first one considering that he pockets the money up front. If I am right, one could forfeit the 10 days risk free rate to increase the chances of being filled, that would be a fair tradeoff wouldn't it?