What a futures contract is

Strip away the jargon and a futures contract is one of the oldest, simplest ideas in commerce: a promise, made today, about a trade that will happen later. I agree to buy this from you in a month, and we fix the price now. A farmer and a mill have struck that bargain for centuries — the farmer locks in a price for a harvest not yet cut, the mill locks in its cost. Both know today what will happen in a month. That certainty is the whole point of the instrument.

The stock-market version keeps the shape and changes the purpose. Almost no one trading a stock future intends to deliver or receive shares. They are there for the price move in between — and, above all, for the leverage, because a future lets you control a large amount of stock while posting only a small deposit. That is where the ancient, sensible promise turns into something a beginner can be ruined by.

This module does just one thing: make the contract itself completely clear — what you are promising, how much you are really promising, and why the promise cuts both ways. Everything later in this Part — margins, cost of carry, rollover — sits on top of this. Get the contract right and the rest has somewhere to stand.

Futures were invented to remove uncertainty for people with something real at stake. A jeweller who will need gold in three months does not want to gamble on the price; a future lets her fix it today and sleep. This is hedging, and it is the one genuinely defensible use of derivatives — the subject of a whole later module. For the hedger, the future is insurance: it trades away an unknown for a known.

The reason a future can do this is that it is standardised and exchange-traded. Rather than two parties negotiating a private deal and each hoping the other honours it, the exchange defines a uniform contract — a fixed quantity, a fixed expiry — and stands in the middle through its clearing corporation, guaranteeing that the winning side gets paid even if the losing side vanishes. That guarantee is what makes futures liquid and safe to transact. Note the careful word: safe to transact is not the same as safe to hold. The clearing house protects the market from your default; it does nothing to protect you from a bad price.

For most retail traders, though, the contract exists for a different reason than hedging, and it is worth being honest about it: leverage. A future lets you take on ₹5,00,000 of stock exposure for a deposit of perhaps ₹75,000. You do not have to own the shares, borrow explicitly, or pay for them in full. The instrument delivers the amplification of margin with the tidiness of a single trade — which is exactly why it is so easy to take on far more size than you can survive without noticing you have done it.

Three ideas make up the contract. Take them in turn.

The contract is standardised, so you trade it in lots. You cannot buy "one share's worth" of a future. Each future has a fixed lot size — the quantity of the underlying (the stock or index the contract is based on) that one contract controls — and you trade in whole lots only. If the lot size is 500 shares, the smallest position you can take is 500 shares' worth, whether you like it or not. The exchange sets and revises these sizes; for stock futures they are set so one lot is a substantial amount of money, which is the first quiet reason futures are not a small-stakes instrument.

Your real size is the notional, not the margin. Multiply the price by the lot size and you get the notional value — the full economic size of what you control. A ₹1,000 stock with a 500-share lot is a notional of ₹5,00,000. illustrative You might enter that contract by posting only ~₹75,000 of margin, but your profit and loss move with the whole ₹5,00,000. This gap — small deposit, large exposure — is leverage wearing a contract's clothing, and it is the number that matters. A 5% move in the stock is ₹25,000: a third of your margin, gained or lost, from a position that felt like ₹75,000.

There are two sides, and they mirror each other exactly. Every future has a buyer and a seller. To go long is to agree to buy at the fixed price — you profit if the price rises. To go short is to agree to sell at the fixed price — you profit if the price falls. And here is the fact this module exists to plant: the two sides are symmetric. Whatever the long gains, the short loses, rupee for rupee, and vice versa. A future is a zero-sum agreement between two people about the same move (before costs, which make it negative-sum overall).

Look at the shape and read what it says. Both lines are straight — they do not bend or flatten. That means the loss on each side keeps growing with the move, with no built-in floor. This is the crucial difference from an option, which you will meet later: an option buyer can lose only the premium, a curve that flattens. A future has no such mercy on either side. The line just keeps going.

Sit with one contract. illustrative

Two traders take opposite sides of the same stock future. The stock is ₹1,000, the lot is 500 shares, so the notional is ₹5,00,000 and each posts about ₹75,000 of margin. Priya goes long — she agrees to buy at ₹1,000, betting the stock rises. Vikram goes short — he agrees to sell at ₹1,000, betting it falls. Neither owns any shares; both have simply put up a deposit against a promise.

The stock rises to ₹1,100 by expiry — a 10% move, unremarkable for a single stock over a month. Priya's long gains ₹100 a share × 500 = ₹50,000, on her ₹75,000 margin: a 67% return on her deposit from a 10% move in the stock. That is leverage flattering her. Vikram's short loses ₹100 a share × 500 = ₹50,000 — two-thirds of his margin gone, from the same ordinary move. His gain and her loss are the same number with opposite signs. Reverse the move — stock falls to ₹900 — and the mirror flips exactly: Vikram makes ₹50,000, Priya loses it.

Now push the unpleasant case. Suppose news breaks and the stock jumps to ₹1,400. Priya's long is up ₹200,000 — wonderful for her. Vikram's short is down ₹200,000, on ₹75,000 of margin. His loss is far larger than the deposit he put up; he will face margin calls long before this, and if he cannot meet them, his position is closed at a loss that exceeds what he staked. And notice: there is no natural ceiling on how high the stock can go, so there is no natural limit to the short's loss. The line just keeps climbing.

The neat, symmetric payoff diagram tells you what happens to your money at each price. It cannot, on its own, tell you the two things that decide whether you survive holding it.

First, it hides how little the market has to move to hurt you, because the picture is drawn against the notional while your money is the margin. A payoff line that looks gently sloped in stock-price terms is steep in margin terms: the leverage multiplies the slope. A 5% move — a quiet day — can take a third of your deposit. The diagram's calm geometry disguises how twitchy the position is relative to what you actually put up. A straight payoff line with no floor is a line that can reach zero capital before your view has a chance to be right.

Second, and more dangerous: the symmetry seduces people into thinking there is a safe side. There is not. Because the long and short are mirror images, whatever open-ended risk one faces, so does the other, in the opposite direction. Shorting feels conservative — "I'm betting on a fall, prices can only go to zero" — but a short's loss grows as the price rises, and a price has no upper limit. A stock that jumps on a takeover or a result can gap far past any level you imagined, and the short wears every rupee of it. The move that ruins a leveraged future is exactly the sudden jump that ordinary intuition treats as impossible. Neither side is the safe side. Both hold a line that does not bend.

The contract is simple, which is exactly why the errors are consistent.

1. Mistaking margin for the trade size. The deposit feels like the bet, so a ₹75,000 margin feels like a ₹75,000 risk. The real size is the ₹5,00,000 notional, and every gain, loss and margin call scales with it. This one misreading is behind most futures blow-ups.

2. Thinking one lot is "just a small position." Lot sizes are set so one contract is a large sum. "Only one lot" can still be ₹5,00,000 of exposure — there is no small position available, which is why futures are not a place to learn with pocket change.

3. Believing shorting is the cautious side. Selling feels defensive and prices "can only fall to zero", so shorting seems safer. But a short loses as the price rises, and prices have no ceiling — the short side carries the more open-ended risk, not the less.

4. Reading the straight line as if it flattened. Beginners who have half-heard about options assume a future also caps the loss somewhere. It does not. Neither side's payoff bends; the loss grows with the move, without a floor.

5. Confusing 'safe to transact' with 'safe to hold'. The clearing house guarantees you get paid and the market keeps working. It does not protect you from a bad price. The central guarantee is for the market's integrity, never for your capital.