I'm investigating calendars and diagonals. So I'm at the point of watching prices. I have a mildly bullish bias on CEPH this morning, so I give it a look. I build a call calendar spread with a strike price @ 80. (Bullish calendar). And then for grins, I looked at a put calendar spread to see the price difference, because they're equivalent, correct? I see a pretty significant price difference. Let's say for grins, I can get filled at the mid. The price of the call calendar is .75 and the put calendar is .50. I've attached a screen shot to help someone help me figure out where I'm going wrong. I know I've asked this question about vertical spreads, but the spread difference was usually a nickel. This seems much more substantial. Thank you.