Contango and Backwardation

Pull up the futures prices for any commodity and you get a little ladder: a price for delivery next month, one for the month after, one for next December. That ladder almost never sits flat. Either the far months cost more than the near ones, or they cost less, and those two shapes have names. Contango is when later delivery is more expensive. Backwardation is when later delivery is cheaper.

The plain-language reason is scarcity today versus rent tomorrow. Think of bottled water. In a normal week, water for delivery in six months costs slightly more than water today, because whoever holds it for you has to warehouse it and finance it. Now a hurricane hits and the shelves empty. Water right now becomes worth far more than water in six months, when everyone agrees the trucks will be running again. The curve has flipped: today's price is above the future's. Contango is the rent-charging world; backwardation is the hurricane world.

Why a curve picks a side

The shape is decided by the tug-of-war in the Cost of Carry and Storage equation. Financing and storage push the far months up; the convenience yield, the value of having the physical goods in hand today, pushes them down. When inventories are ample, nobody pays extra to hold real barrels, the convenience yield is small, and carry wins: contango. When inventories are thin and a factory could genuinely run out, the convenience yield spikes above carry and the curve inverts: backwardation.

That is why the shape is one of the most watched inventory signals in commodities. Deep contango usually means tanks are filling. Steep backwardation usually means they are draining.

Traders rarely say "the curve is in contango" and leave it there; they quote a number. The usual one is the calendar spread, the first contract minus the second, so a negative spread is contango and a positive one is backwardation. Curves also do not have to pick a single side for their whole length: natural gas is routinely backwardated into winter and in contango through the shoulder months, because the scarcity is seasonal rather than permanent.

The part that costs real money: roll yield

Futures expire. If you want continuous exposure you must keep selling the expiring contract and buying a later one, month after month. That is rolling, and the price gap you cross each time is Roll Yield. It is where the curve shape stops being a diagram and starts showing up in your account.

Contango, worked through. Crude for next month trades at $70.00, the month after at $71.40. You are long the near contract. At the roll you sell at $70.00 and buy at $71.40, so you now own a contract that costs $2\%$ more. Suppose spot goes absolutely nowhere: a month later, that contract has become the front month and converges back to about $70.00. You have lost $1.40 per barrel, $2\%$, on a flat market. Repeat it twelve times and $0.98^{12} = 0.785$, a drag of about $21.5\%$ a year purely from the shape of the curve.

Backwardation, worked through. Now the near contract is $82.00 and the next is $80.36. You sell at $82.00 and buy at $80.36, which is $2\%$ cheaper. Spot again goes nowhere, so that contract converges up to $82.00 and you gain $1.64 per barrel. Twelve rolls of that and $1.0204^{12} = 1.274$, a tailwind of about $27\%$ a year. Same flat spot price, same trade, opposite result, and nothing about it involved predicting anything.

What this means in practice

This is why commodity index funds and exchange-traded commodity products can track spot prices so badly. A fund holding front-month oil in persistent contango grinds lower even when oil is flat, which is exactly what happened to retail oil trackers through 2015 and again in 2020, so index designers spend real effort on Commodity Index Roll Mechanics to spread rolls across the curve. It is also why "long backwardated commodities, short contangoed ones" is a genuine systematic strategy: you are harvesting roll yield rather than forecasting prices. Volatility markets play the same game, since VIX futures sit in contango most of the time and invert violently in a crash.

Key terms

• Contango — futures priced above spot, an upward-sloping curve.
• Backwardation — futures priced below spot, a downward-sloping curve.
• Roll — closing an expiring contract and reopening in a later one.
• Roll yield — the gain or loss from crossing the curve at each roll.
• Normal backwardation — Keynes's separate idea that futures sit below expected future spot because hedgers pay speculators to take price risk.