Margin in Futures: Initial Margin and Exposure Margin

A future is simply a contract to buy or sell something at a fixed price on a future date. In India the "something" is usually an index like the Nifty, or a single share like Reliance.

The puzzle is the money. If one Nifty contract controls ₹18 lakh worth of the index, why does the broker let you in for a fraction of that?

Because you are not buying the ₹18 lakh. You are putting down a deposit against it. That deposit is the margin — and it comes in layers with names like SPAN and exposure that nobody explains to you up front.

This article unpacks all of it, in plain words: what margin really is, the two pieces that make up the money you block to open a trade, the rupee math on one real Nifty lot, the SEBI rule that changed everything in 2021, and why your margin keeps moving even when you do nothing.

Here is the trap to fix in your head before anything else. You rarely blow up because you don't know the word SPAN. You blow up because the screen shows ₹2 lakh — and your mind quietly forgets that the trade is riding on ₹18 lakh.

Margin is a deposit, not a price

Here is the single idea everything else hangs on. Margin is not what the position costs. It is a security deposit you leave with the exchange to prove you can cover your losses.

Think about renting a flat. The flat might be worth ₹1 crore, but you do not pay ₹1 crore to move in.

You pay a security deposit — say two months' rent — that the owner holds in case you cause damage. You get it back when you leave, less any damage you caused.

Futures margin works exactly the same way.

The fact that a small deposit controls a large position is called leverage — using a little of your own money to take a much bigger exposure to the market.

Leverage cuts both ways, and this is the part that trips up almost everyone. The profit and loss are calculated on the full ₹18 lakh, not on the ₹2 lakh you put down.

If the Nifty moves 2%, that is about ₹36,000 on one lot — a swing of roughly 16% on your ₹2 lakh deposit, in a single day. The deposit is small; the consequences are not.

Initial margin = SPAN + exposure

The total deposit blocked when you open a position has a name: the initial margin. It is the money that must be sitting in your account before the trade goes through.

That initial margin is built from two parts, stacked on top of each other. Let's meet them one at a time.

Part one — SPAN margin (the worst-day estimate)

SPAN stands for Standard Portfolio Analysis of Risk. It is a risk-calculating system the exchange runs — you never see the maths, only the number it produces.

What SPAN does is simple to describe. It asks: if tomorrow goes badly, what is the worst one-day loss this position could reasonably suffer? That estimated worst-case loss is the SPAN margin.

"Reasonably" has a precise meaning here. SPAN is set to cover the loss on 99 days out of 100 — what risk people call 99% confidence — over a one-day horizon, which the exchange stretches to two days for some contracts where a loss cannot be collected before the next trading morning. It is the larger of the two layers.

Part two — exposure margin, or ELM (the extra cushion)

SPAN covers the expected bad day. But markets occasionally do something wilder than any model expects — a gap-down on bad news, a crash, a frozen, one-way session.

The exposure margin is a second, smaller cushion stacked on top of SPAN to absorb exactly those surprises. "Exposure margin" is the everyday trader's term; in NSE's own documents it now has an official name — the Extreme Loss Margin, or ELM.

For index futures, NSE currently sets the ELM at a fixed 2% of the contract value. For single-stock futures it is higher — 3.5% — because one company can swing far more violently than a whole index.

Add the two together and you have the initial margin:

So on a contract worth roughly ₹18 lakh, you block roughly ₹2.16 lakh — a little over 12% — to open one lot. SPAN is the big block; the ELM is the thin slice on top.

That 12% is not a fixed law. Across Indian equity futures the all-in initial margin usually lands somewhere around 12 to 15% of the contract value, and it rises when markets get jumpy.

Four margin words, sorted out

Once you start reading about futures, four similar-sounding words show up and blur together. Here they are, side by side.

The key split: initial margin is a deposit blocked once, when you enter. Mark-to-market is a daily cash settlement that happens every evening you hold the trade.

If the market goes against you and your deposit gets eaten into, the broker asks you to top it back up. That request is the dreaded margin call — and ignoring it means your position can be squared off — closed out by the broker, whether you like it or not — automatically.

Why you can't "pay margin later" anymore

There used to be a loophole. Brokers would let you take a position first and arrange the margin later in the day, which meant traders routinely held positions far larger than the money they actually had.

SEBI — the Securities and Exchange Board of India, the market regulator — closed that door. Since 1 September 2021, the full margin must be available in your account before the trade is placed. This is the "100% upfront margin" or "peak margin" rule.

It did not arrive all at once. SEBI phased it in gradually — 25% of the peak margin at first, then 50%, then 75%, and finally the full 100% by that September date.

The "peak" part matters. Through the trading day, the clearing corporation takes at least four randomly timed snapshots of how much margin your positions need. The highest of those readings is your peak margin — and you must have had it covered.

For a beginner this rule is a feature, not a bug. It quietly stops you from taking a position you cannot actually afford — the exact mistake that wipes out new F&O (futures and options) accounts.

One related point worth knowing: at least half of your margin must be kept as cash or cash-equivalent funds. You cannot fund the entire deposit with pledged shares — a real chunk of it has to be actual money.

Why one lot now needs ₹2 lakh, not ₹50,000

If you read older articles, you will see much smaller margin figures — and there is a reason the numbers jumped.

Through 2024, SEBI worried that too many small retail traders were being drawn into F&O and losing money. So it raised the minimum size of an index derivatives contract.

The minimum contract value went from around ₹5 lakh up to ₹15 lakh, for new contracts from late November 2024. To hit that, the exchanges increased lot sizes — the Nifty lot, for example, went from 25 units to 75.

A bigger lot means a bigger contract value, which means a bigger margin. The percentage didn't change; the base it applies to did. One lot that once needed well under ₹1 lakh now needs over ₹2 lakh.

Three ways margin quietly hurts beginners

None of these are about getting the market direction wrong. They are about misreading the deposit.

One. Treating the full margin as your trading budget. If you have ₹2.5 lakh and one lot needs ₹2.16 lakh, you can open it — but you have almost no buffer left for a bad day. A small move against you triggers a margin call you cannot meet.

The fix is to keep a cushion. Experienced traders rarely deploy their whole balance into margin; they leave room for the position to breathe and for the inevitable top-up.

Two. Forgetting that margin rises in a storm. The day you most want to hold your position — a sharp, scary fall — is the exact day the exchange raises SPAN margin. Your required deposit goes up just as your account is hurting.

Plan for it. The margin you saw on a calm afternoon is not the margin you will face in a crash.

Three. Confusing leverage with affordability. Being allowed to control ₹18 lakh with ₹2 lakh does not mean you should. The loss is calculated on the full ₹18 lakh, and it can exceed the deposit you put down.

Unlike buying a share — where the worst case is the share going to zero — a leveraged futures position can lose more than you deposited, leaving you owing the broker.

This is not a rare edge case. A SEBI study covering the three years to March 2024 found that about 93% of individual traders in equity derivatives lost money, giving up well over ₹1.8 lakh crore between them.

Most of that pain begins exactly here — sizing a position off the margin on the screen instead of the real exposure behind it.