Just following up on this.ZM F18/H18 has moved a lot in July because H is becoming the first "brazilian discount" month. Apparently,it is a structural change due to south brazil harbors . So well, in my book, this trade is still a good one because of the low risk but F18/H18 moves won't have much influence on Z17/H18.I went long ZM Z17/F18 this morning @ -1.7:
-Historically low. Low risk.
-F18/H18 went inverse in early July and is currently @ 0. It indicates supply can be tighter in early '18.
-You never know with current drought.