Equity Index Future

Also known as: Index futures, E-mini, Single-stock future

A standardised, exchange-traded promise to buy or sell the market at a set price on a set date.

3 min read · 568 words · Updated

1 · SnapshotThe one idea to remember
Key intuition: futures are the fastest, cheapest way to move big equity exposure — one liquid trade instead of buying 500 stocks.
2 · BeginnerWhat is it, really?

A future is a binding agreement today on a price for a future date. An S&P 500 future struck at 5,000 obliges the buyer to "take delivery" of the index level at expiry: if the index ends at 5,200 the buyer gains 200 points; at 4,800 they lose 200. Unlike an option there is no choice and no premium — just a locked-in price, with symmetric gains and losses.

Futures trade on exchanges in standard sizes and dates, and a clearing house stands between every buyer and seller, so you never worry about the other side defaulting. To trade you post margin — a good-faith deposit of a few percent of the contract's value — which makes futures powerful and dangerous: a 5% margin means 20x leverage.

P&L of a long future at expiry: linear in the index, gains above the traded level F₀, losses below.
F₀Long futureUnderlying price at expiryProfit / loss

Point at a line to pick it out from the others.

No purchase price, and a bill every single day
The buyerlong the futureThe sellershort the future1Nothing is paid2The day's gain, in cash3The day's loss, in cash4Almost nothing is left tosettle

a paymentonly if a condition is metnot a payment

Compare with the forward on the next page: identical economics, settled every day instead of once — and that is a cash-flow difference, not a technicality.

On the trade date

  1. The buyer → The seller A price is agreed and the contract is worth zero to both sides. Nothing is bought and there is no premium.

Every day until expiry

  1. The seller → The buyer If the future rose, the buyer is paid that move before the next session and the seller funds it.
  2. The buyer → The seller Settled, not accrued. A position that has moved against you consumes cash today whatever it will be worth at expiry — which is how a correct hedge can still run a firm out of money.

netted daily: one figure before the next session

At expiry

  1. The seller → The buyer Index futures settle in cash, and by then nearly all of the profit or loss has already changed hands day by day.
Who is really on the other side, and what secures itafter the trade
Your brokera clearing memberClearing houseEither side2Passed up the chain3Variation margin, bothways1Initial margin, a performancebond

a paymentnot a payment

At the trade

  1. Either side → Your broker Sized to a modelled bad day. It is not a down payment and it is not part of the price.
  2. Your broker → Clearing house The broker faces the clearing house; you face the broker. If your broker fails, how well your position is segregated decides what happens to it.

Every day

  1. Clearing house → Your broker The clearing house collects from the losers and pays the winners before the next session opens. It never carries a position of its own.
Asset class
Equity derivatives
Instrument type
Future (linear)
Traded
Exchange, centrally cleared
Typical users
Asset managers, hedge funds, index arbitrageurs

Which risks decide the outcome

Not how risky this is, and not a rating — there is deliberately no total. It says which of five failure modes drives what happens here, in the same order on all 129 products so they can be compared. This publication's own reading; see the notice below.

  • Marketdecides it
  • Creditbarely applies
  • Liquiditybarely applies
  • Fundingdecides it
  • Operationalbarely applies

What decides it here. The market decides the profit, and funding decides whether you are still there to collect it. Daily settlement turns a paper loss into cash owed today.

What the five mean, and which one decides where →

3 · IntermediateHow it works in practice

Daily settlement

Futures are marked to market daily: every evening, gains are credited and losses debited in cash ("variation margin"). Your position economically resets each day — which is why a futures P&L hits your account long before expiry. Index futures are cash-settled: no shares change hands, just the final difference.

Why the future ≠ the index

The future usually trades above or below the spot index. Holding stocks costs money (funding) but earns dividends; the future does neither. Fair value reflects this cost of carry, and the gap ("basis") converges to zero at expiry.

Uses

  • Beta management: a pension fund equitises cash inflows instantly with futures, then buys stocks at leisure.
  • Hedging: shorting futures against a portfolio strips out market risk without selling holdings.
  • Rolling: positions are maintained by selling the expiring contract and buying the next ("the roll"), whose price embeds funding and dividend expectations.
Worked example: E-mini S&P futures have a $50 multiplier. Long one contract at 5,000 = $250,000 exposure for roughly $12,000 margin. A 1% index rise (+50 points) earns 50 × $50 = $2,500 — about 20% on margin posted.
4 · AdvancedPricing & valuation

Cost-of-carry pricing

Cash-and-carry arbitrage (buy the basket with borrowed money, sell the future) enforces, with financing rate \(r\) and dividend yield \(q\):

$$ F_0 \;=\; S_0\, e^{(r - q)T} $$
What the symbols mean
  • Fthe forward or futures price
  • Sthe price of the underlying today
  • rthe interest rate, per year
  • qthe dividend yield, per year
  • Tmaturity, in years

With discrete dividends, \(F_0 = (S_0 - \text{PV(divs)})\,e^{rT}\). If the traded future sits above fair value, arbitrageurs sell futures and buy stock (and vice versa), pinning the basis to funding and dividend expectations.

What the basis tells you

The implied financing rate backed out of the futures roll is a market price of balance-sheet capacity. When dealers' balance sheets are scarce (regulation, year-end), equity futures can trade "rich", meaning longs pay above risk-free funding — measurable as the spread of the implied repo rate over OIS.

Margin and tail risk

Initial margin is set from tail-risk models (historical/filtered VaR, e.g. ~99.5% over a 1–2 day horizon). Leverage means variance drag and forced liquidation risk: a position sized at margin minimum can be stopped out by a move the underlying later recovers from.

Futures vs. forwards

Daily settlement makes futures prices differ slightly from forward prices when rates correlate with the underlying (the convexity adjustment) — negligible for short-dated equity futures, material for long-dated rate futures.

The formulas above are standard textbook formulations, simplified for teaching. They explain the mechanism — they are not a valuation tool, and they will not reproduce a dealer’s price.

5 · Desk notesHow practitioners think about it
Practitioner note: the quarterly roll cost, annualised, is the true price of maintaining synthetic equity exposure — compare it to your own funding before choosing futures over cash or swaps.

Now say it back

Close the page and give Equity Index Future in four sentences. It takes a minute and it is the only way to find out whether reading it was enough.

  1. Who wants what — two parties wanted opposite things badly enough to write it down.
  2. What the contract obliges, and when — not the payoff; the obligation.
  3. Where the money comes from — name the source, or you have described a hope.
  4. What makes it lose — the ordinary way, not the dramatic one.

Do it with a clock → · why these four

Put Equity Index Future beside any other instrument →

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Total Return Swap

One leg pays everything an asset earns — price moves and income — the other pays funding. Ownership economics without ownership.

Where this instrument shows up elsewhere

Information and education only. Every page, figure and calculator on this site exists to explain how financial instruments work. Nothing here is investment, tax or legal advice, a recommendation, or a valuation you can rely on. Full disclaimer