Well, in this case I'm long the front month (week in this case), so that's not a problem. It is indeed, but because the sold position is much higher in nominal terms, so the IV of the first one would have to increase much more than the second one to win money that way (and I'd have to close the bought put before expiration, to profit from that IV increase).
So, your thinking of doing a Reverse Calendar in the course of a normal market? Not a lot of things beat the efficiency of a butterfly/straddle to just go long vol except maybe for the Vix, but I am not sure about that either.
Here is your spread as a 10x10 (expressed with an SPX 5x5) and volatility shocks are exaggerated for illustration. You can disregard the right side of the blue V and left side of the tan V since these vol scenarios are unlikely. This trade is capital intensive and commission intensive. Theta is miniscule 66 (a week prior to expiration) compared to the potential adverse vol shock. Not a lot of things to like.
You might want to look at old threads by convexx on how he would trade these situationally.
Last edited: