Using the most recent example, the NG Nov ’17 contract expired on the 27th of Oct @ ~$2.75 while the Dec ’17 contract was @ ~$2.95 on Oct 27th.
There was basically a $0.20 gap between the spot and the expected delivery price 4 weeks into the future, so that would imply that the spot/Dec contract would eventually converge by Nov 27th.
Based on this, it seems to be really obvious to long the spot price and short the Dec ’17 future, but that’s not the case right? Even if I wanted to long spot…