Streetwise Professor

November 14, 2018

Return of the Widowmaker–The Theory of Storage in Action

Filed under: Commodities,Derivatives,Economics,Energy — cpirrong @ 7:37 pm

I’m old enough to remember when natural gas futures–and the March-April spread in particular–were known as the widowmakers.  The volatility in the flat price and especially the spread could crush you in an instant if you were caught on the wrong side of one of the big movements.

Then shale happened, and the increase in supply, and in particular the increase in the elasticity of supply, dampened flat price volatility.  The buildup in production and relatively temperate weather encouraged the buildup in inventories, which helped tame the HJ spread.  But the storage build in 2018 was well below historical averages–a 15 year low.  Add in a dash of cold weather, and the widowmaker is back, baby.

To put some numbers to it, today the March flat price was up 76 cents/mmbtu, and the HJ spread spiked 71.1 cents.  The spread settled yesterday at  $.883 and settled today at $1.594.  So for you bull spreaders–life is good.  Bear spreaders–not so much.

The March-April spread is volatile for structural reasons, notably the seasonality of demand combined with relatively inflexible output in the short run.  As I tell my students, the role of storage is to move stuff from when it’s abundant to when it’s scarce–but you can only move one direction, from the present to the future.  You can’t move from the future to the present.  Given the seasonal demand for gas it is scarce in the winter, abundant in the spring, meaning that carrying inventory from winter to spring would be moving supply from when it’s scarce to when it’s abundant.  You don’t want to do that, so the best you can do is limit what you carry over, so you don’t carry it from when it’s scarce to when it’s abundant.

Backwardation is the price signal that gives the incentive to do that: a March price above the April price tells you that you are locking in a loss by carrying inventory from March to April.   Given the seasonality in demand, the HJ spread should therefore be backwardated in most years, and indeed that’s the case.

But this has implications for the volatility in the spread, and its susceptibility to big jumps like experienced today.  Inventory is what connects prices today with prices in the future.  With it being optimal to carry little or no inventory (a “stockout”)  from winter to spring, the last winter month contract price (March) has little to connect it with the first spring contract price (April).  Thus, a transient demand shock–and weather shocks are transient (which is why the world hasn’t burned up or frozen)–during the heating season affects that season’s prices but due to the lack of an inventory connection little of that shock is communicated to spring prices.

And that’s exactly what we saw today.  Virtually all the spread action was driven by the March price move–a 76 cent move–while the April price barely budged, moving up less than a nickel.

That’s the theory of storage in action.  Spreads price constraints.  For example, Canadian crude prices are in the dumper now relative to Cushing because of the constraint on getting crude out of the frozen North.  The March-April natty spread prices the Einstein Constraint, i.e., the impossibility of time travel.  We can’t bring gas from spring 2019 to winter 2019.  Given the seasonality of demand, the best we can do is to NOT bring gas from winter 2019 to spring 2019.  Winter prices must adjust to ration the supply available before the spring (existing inventory and production through March).  The supply is relatively fixed (inventory is definitely fixed, and production is pretty much fixed over that time frame) so an increase in demand due to unexpected cold winter weather can’t be accommodated by an increase in supply, but by an increase in price.  The Einstein Constraint plus relatively inflexible production plus seasonal demand combine to make the inter-seasonal spread an SOB.

There will be a test.  Math will be involved.

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