I have been comparing and contrasting verticals vs diagonals, and I don't really see a major advantage of diagonals over verticals. For example, I was looking at the (ES is the underlying)JAN P675/P500. At the time of the look, the credit was for 5.15. The Greeks for the P765: IV=67.12; delta=.0802; gamma=.0008; vega=.4446; theta=-.4819. The Greeks for the P500: IV=88.45; delta=.0127; gamma=.0001; vega=.0823; theta=-.0984. I also looked at the JAN P675/FEB P375. The credit was for 5.05. The Greeks for the FEB P375: IV=87.96; delta=.0062; gamma=.0001; vega=.0786; theta=-.0436. Correct me if I'm wrong, but the advantages I see with the diagonal are: 1) The FEB long Put delta, vega and theta are lower than the Jan long put. This says to me that the FEB long will not lose its value as quickly as the JAN long, and if the underlying does approach the short strike, the FEB Put may actually gain some value. 2) Volatility appears to be a wash between the two longs, and I am not sure of the significance. 3) Once the front-month expires OTM, and a near-month option can be sold, converting the former diagonal to a vertical spread. Looks like I save commissions here. Other things I have read about diagonals: They benefit if IV rises, and they benefit when the near-month IV is higher than the IV in the deferred month ( I assume that one would compare same strikes in different months to see this). They lose if IV collapses ( I don't see this--usually when IV collapses, the market moves up and a profit is seen (the credit received is the minimum profit), or they lose if the market sharply trends downward--which makes no sense if you want IV to increase..unless you want a steady increase of IV--right). I appreciate your comments.