Greeks, vols, skew, etc don't mean jack this close to exp. You are approaching the event horizon ha
ceteris paribus, it'll try to pin 40. Micro-structure is the driver now.
No clue which underlying you’re referring to. But let’s say you’re right, why didn’t you sell the 15 DTE put, and buy the 150 DTE? This would result in a long calendar spread for a credit, which happens to violate the arbitrage bounds of BSM.
If trading is zero-sum. Then someone has to win. In the case of the OP, where did your money go?
If someone is selling a strategy, then it doesn’t work. If their strategy had +EV, then they would be better off trading it themselves than giving it away.
-Long the SPX May10 2875/2925/3000 352 iron fly from 37.15 risk.
Since you have to 2x, to reduce to 1-lot risk, it's = -75.75 / 2 = 37.875, 75-wide - 37.875 = 37.125 risk