Quote from acen1975:
just use a calculator.
last week,with the fall of S&P from 1011 to 980 within couple days,volatility rose from 24 to 29,which is 20%.
so put the numbers in the calculator-a drop of 30 ticks,and change the volatility-once 24,once 29.......
and use let say 900 strike of the spread......you will be surprised.....
as you know time spreads are also volatility spreads-when the spread is ITM there's almost no extrinsic value-the deltas are close to 1,so IV almost doesnt make any good or damage to the spread.........but if the spread is OTM with 100% extinsic.....is totally different story.
IV kicks in strong.
notice that i am talking if the move is small,and IV rises.....if the move goes all the way to the strikes,it really doesnt matter-than it will be the same,but not during the move,when the spread is still away-in that case the value of the spreads will be slightly different,and this difference will be accounted for,from the change in IV
I suggest you read up on Put-Call Parity before continuing your argument.
