Quote from optioncoach:
As volatility increases it will push the higher VEGA positions up more than the lower VEGA positions. There is also a delta difference. I do not have the ES greeks in front of me right now but for illustrative purposes lets look at SPX options of similar strikes and their greeks:
SEP SPX 1200 Put
Vega 1.39
Delta -.20
Gamma -.18
AUG SPX 1225 Put
Vega 1.10
Delta -.24
Theta -.27
As the market goes down and IV increases, the SEP puts have a bigger increase in price due to Vega. Moreover, if the drop in price happens closer to expiration, the theta differential also favors the long puts. Both of these hep against the delta differential between the two which can grow as the market moves lower since the AUG puts have higher gamma.
Murray can explain better from his actual trades
Just imagine the index went down 1 point after one day with a 1% rise in IV to see how the position would react![]()
I used the diagonal and calendar spread in the past. One thing I didn't like was the initial debit. As the market continues to go down, even a rise in IV might not give u any profit. I will try to find a past trade to illustrate it in my next post.

