I'm not yet familiar with all the terminology, sorry if i name anything incorrectly. I'm considering doing a butterfly call spread on a certain stock. I want to buy 1 contract (yes im only playing with around $1,500) of October calls at a certain strike and simultaneously sell 1 July call at the same strike. The premium I collect is about 24%. I realize of course if the stock tanks I could be out as much as 76% of my investment, but thats a risk I'm willing to take. However I am confused on one part, and honestly I may just be doing my math wrong. I'm trying to simulate a price jump of $30 of the underlying on July 15th and I'm assuming the stock stays there until expy. I multiplied the theta by how many days that is from now for both options, subtracted that from the option's current price and then multiplied the deltas respectively for a $30 price jump and added them together to simulate how much each option would be worth. The theta on the option i bought for myself is 0.078 while the theta on the option i sold is 0.115. Also my delta is 40% higher than his. When I do the calculations and assuming he exercises and I have to pay the difference between the strike and the stock price, I end up losing money. Not very much, about 5%-10%. My question is how can this be? With the deltas and thetas being what they are how does the person I sold the option to get "ahead" of me? Also I with there was some kind of simulator thing, bc all these greeks become a pain to deal with. Any advice is appreciated.