The Idea of Hedging with Futures

Every day, a corporate treasurer somewhere is worried about a price. An airline doesn't know what it will pay for jet fuel next quarter. A farmer doesn't know what corn will fetch at harvest. A fund manager doesn't know what a foreign currency will be worth when a dividend comes home. All three can walk onto an exchange and trade a standardized futures contract that locks in today's price for a transaction that won't happen until later. That, far more often than speculation, is what a futures market is for: it is an insurance market for prices.

The mechanics reduce to one question: will you be a buyer or a seller of the underlying asset at the future date?

Long hedge. You will need to buy the asset later (a manufacturer who needs raw material, an airline that needs fuel). You go long futures now — buy the contract — so a rise in the spot price is offset by a gain on the futures.
Short hedge. You will need to sell the asset later (a farmer with a crop still in the ground, a miner with ore still underground, an exporter awaiting a foreign-currency payment). You go short futures now — sell the contract — so a fall in the spot price is offset by a gain on the futures.

In both cases the logic is identical: whichever way the spot price moves, the futures position moves the opposite way by (approximately) the same amount, and the two legs cancel. What's left is a price close to the one you locked in today — chosen in advance, not left to chance.

Worked example — a long hedge: the airline and jet fuel

SkyHigh Airlines will need Q = 5{,}000{,}000 gallons of jet fuel in three months. Today's spot price is \$2.20/gal, and the three-month futures price is F_0 = \$2.15/gal. The treasurer buys futures on 5,000,000 gallons today. Three months later she closes the futures position (sells it back) and buys the physical fuel at whatever the spot price then is. Two scenarios:

Outcome at expiry	Spot rises to $2.60	Spot falls to $1.90
Unhedged fuel cost = Q \times S_T	\$13{,}000{,}000	\$9{,}500{,}000
Futures P&L = Q \times (S_T - F_0)	+\$2{,}250{,}000	-\$1{,}250{,}000
Net cost	\$10{,}750{,}000	\$10{,}750{,}000

Both scenarios land on the same number: Q \times F_0 = 5{,}000{,}000 \times 2.15 = \$10{,}750{,}000. Whichever way the market moved, the long futures position exactly cancelled the change in the fuel bill, leaving the airline paying the price it locked in three months earlier — not the highest price it could have paid, not the lowest, but a known one, fixed while the budget was still being drawn up.

Worked example — a short hedge: the farmer and corn

A corn farmer expects to harvest Q = 50{,}000 bushels in six months and wants to lock in today's futures price, F_0 = \$4.50 per bushel, rather than gamble on where the market will be at harvest. She sells 50,000 bushels of futures today. At harvest she closes the futures position and sells the physical corn at the spot price.

\text{Net revenue} = \underbrace{Q\,S_T}_{\text{sell the corn}} + \underbrace{Q\,(F_0 - S_T)}_{\text{short futures P\&L}} = Q\,F_0.

If corn crashes to \$3.80 at harvest, the futures gain (50{,}000 \times (4.50 - 3.80) = \$35{,}000) tops up the lower sale proceeds. If corn instead rallies to \$5.20, the futures position loses \$35{,}000, exactly clawing back the extra she'd have made selling unhedged. Either way, net revenue is 50{,}000 \times 4.50 = \$225{,}000 — the price she wanted from the start.

The farmer who hedges gives up the chance of a windfall if corn prices spike. So why do it? Because a business isn't in the business of forecasting corn prices — it's in the business of growing corn, or flying planes, or whatever its actual trade is. A hedge doesn't try to make money on the price move; it tries to make the price move irrelevant, so the firm can budget, borrow, and plan around a number it can rely on instead of one it has to guess.

This is exactly the logic of buying fire insurance on a warehouse: you accept a certain small cost (the premium, or here, whatever gap opens between the locked-in futures price and where the market happens to land) in exchange for eliminating a large uncertain one. Shareholders who want pure commodity-price exposure can always buy the commodity, or an unhedged airline stock, directly — they don't need the airline's operations team to make that bet for them with the fuel budget.

Seeing it: the hedge flattens the price line

Plot the price you actually end up paying (a long hedge, buying the asset later) against the spot price that happens to prevail at expiry. Unhedged, that's the 45° line — you pay whatever the market charges. Hedged, it's flat: whatever S_T turns out to be, the futures P&L absorbs the difference and you always land on F_0. Drag the slider to move the locked-in price and watch the flat line track it, indifferent to the diagonal underneath.

The single most common misunderstanding about hedging: "if I hedge, I'll do better." Look again at the airline example — if fuel had fallen to $1.90 instead of risen, the unhedged airline would have paid only $9.5m, a full $1.25m less than the hedged outcome of $10.75m. Judged after the fact, the hedge looks like a bad trade in that scenario.

That's not a flaw in the logic — it's the whole point. A hedge doesn't improve your expected outcome (in a fair market it's close to a wash, before transaction and margin costs); it reduces the variance of the outcome. You are trading away the chance of a lucky low price in exchange for removing the risk of an unlucky high one. Anyone who hedges and then complains "the market moved in our favor and we missed out" has misunderstood what they bought. And in reality it isn't even perfectly free of risk: the contract you can trade rarely matches your exact exposure exactly — a mismatch called basis risk, next up.