Quote from falconview:
"You are right in that the bear call vertical benefits from vol drops on a positive print, but only when vols are >30 is that benefit going to outweigh the delta loss."
Been re-reading the debate. Excellent when you get two experienced money making professionals on here. The above comment left me puzzled. Read it three or four times but the VIX at 30 or greater outweighing the delta loss left me stumped as to what was meant by it?
Let me see if I can explain it simply. The basis of the problem is both Delta and Gamma as the two are related.
Delta = the amount that a certain option contract changes proportionate to the move in the underlying. i.e. if the underlying gains $1 and the option gains $0.5 then the delta is 50.
Gamma = the amount that Delta moves with a given move in the underlying.
IOW, delta is not static. The front strike on the vertical spreads you are selling might have a delta of 10 or less because they are far OTM. If the underlying moves against you hard, that strike might then have a delta of 40. But it is not the delta that kills you, it is the gamma. Because, as the underlying moves against you, the front strike is going to move faster then the back strike, because it has higher gamma. This higher gamma means that it is only going to get worse as the underlying moves closer to your front strike.
Now we get to the point I was trying to make before. The other main factor in option pricing is IV, which is currently @ about 18. Since the vol floor is right around 12-14, the most you can expect for is a 200bp IV drop on a +40 print. That will not be close to enough to offset the delta losses. Your vertical that you sold for 0.10 might be worth 1.00 now.
OTOH, if vols were >30 when you sold the spread, then a +40 print would maybe get you >500bp vol drop. That's a lot better in offsetting those delta losses.
The point is, buy low, sell high. It applies to volty as much as price.