Oil shot to nearly $80 a barrel this week after U.S. President Donald Trump walked away from the Iran nuclear deal and the futures market structure shows investors are preparing for a tight supply-demand balance to get even tighter.  Brent crude futures are hovering around $77 a barrel, having risen by around 10 percent in the last six weeks as U.S. rhetoric around Iran grew increasingly hawkish. But it is the widening of the premium of the nearer-dated contracts over those for delivery further in the future that highlights investors’ concern over the already-delicate balance between crude production and consumption. The so-called “Dec/Dec” spread, the difference between the nearest December Brent contract and that for December the following year, is at its widest for five years, […]