Extreme Loss Margin: The Extra Cushion on Every F&O Position

Every F&O trader has seen the margin number on the order screen and wondered why it is higher than the SPAN figure people quote. A big part of that gap is the extreme loss margin, or ELM. It is a flat percentage that the clearing corporation adds on top of the risk-model margin, and it exists for one reason: models miss things.

This guide walks through what ELM is, the exact rates NSE Clearing applies today, the special cases that trip people up, and what it means for how you size a position. All the rates below come from NSE Clearing’s equity derivatives margins page. The rupee examples are hypothetical and only there to show the arithmetic.

What the extreme loss margin actually covers

Start with the main margin. NSE Clearing uses SPAN (Standard Portfolio Analysis of Risk), a portfolio-based system, and it collects initial margin up front on every open position. According to NSE Clearing, that initial margin is based on a 99% value at risk over a one-day horizon. For futures, where mark-to-market money may not be collected before trading opens the next day, the horizon is stretched to two days.

Ninety-nine percent sounds safe. It isn’t the whole story. A 99% one-day VaR, by design, says nothing about the remaining 1% of days, and those are the days that blow up accounts and, occasionally, brokers. A crash on a surprise policy move, a stock that gaps 20% on a fraud allegation, an index that whipsaws on expiry afternoon. That is the tail.

ELM is the buffer for that tail. It is not computed from a volatility model. It is a fixed slice of the position’s notional value, charged on top of SPAN. When NSE Clearing raised it for expiry day in 2024, its circular of October 21, 2024 said the purpose was to increase tail risk coverage.

SPAN prices the risk a model can see. Extreme loss margin is the clearing house admitting that the model will sometimes be wrong, and charging you in advance for that possibility.

Current extreme loss margin rates on NSE

Here is the schedule as NSE Clearing publishes it for futures and options on indices and stocks:

• Index derivatives: 2% of notional value.
• Stock derivatives: 3.5% of notional value.
• Short index options, deep out of the money (strike more than 10% away from the previous day’s closing underlying price): 3%.
• Short index options with more than nine months to expiry: 5%.
• Short single-stock options, deep out of the money (strike more than 30% away from the previous close): 5.25%.
• Expiry day: an additional 2% on short index options that expire that day.

Two things stand out. Stocks carry a higher rate than indices, which makes sense because a single company can fall off a cliff in a way a 50-stock index rarely does. And the deep out-of-the-money option seller pays more, not less. That surprises people, so we will come back to it.

What “notional value” means here

ELM is a percentage, so the base matters. NSE Clearing defines notional value differently for futures and for short options:

• For a futures contract, it is the contract value at the last traded price or closing price.
• For a short options contract, it is the value of the underlying index, or of an equivalent number of underlying shares, based on the last available closing price.

Read the second line again. For an option seller, ELM is charged on the full value of the underlying the contract represents, not on the premium collected. Sell an option for a few rupees of premium and the ELM is still worked out on the entire underlying exposure. That is why option selling ties up so much more capital than option buying.

Worked examples with hypothetical numbers

The figures below are made up for illustration. Lot sizes and prices are assumptions, not current contract specifications. Check your broker’s margin calculator for live numbers.

1. Long index futures

Say an index future trades at 25,000 and one contract covers 75 units. Notional value is 25,000 × 75 = ₹18,75,000. At the 2% index rate, ELM is ₹37,500. That sits on top of whatever SPAN asks for.

2. Short stock futures

A stock future at ₹1,200 with a contract of 500 shares has a notional value of ₹6,00,000. At 3.5%, ELM is ₹21,000. Same rupee exposure as an index position would cost noticeably more in ELM, because the stock rate is 1.75 times the index rate.

3. Selling a deep out-of-the-money index put

Take the same index, previous close 25,000, and a put at the 22,000 strike. That strike is 12% below the close, so it counts as deep out of the money under the more-than-10% rule. The notional value is the underlying value: 25,000 × 75 = ₹18,75,000. At 3%, ELM is ₹56,250, even if the premium received is tiny.

Now say it is expiry day for that contract. The extra 2% kicks in, and NSE Clearing’s circular shows exactly this case: a deep out-of-the-money Nifty option goes from 3% to 5% on its expiry day. In our example, ELM rises to ₹93,750. A near-the-money short index option in the same circular goes from 2% to 4%.

4. A futures calendar spread

Suppose you are long the near-month index future and short the far-month one. NSE Clearing levies ELM on one third of the value of the open far-month position. If the far month trades at 25,200 with 75 units, that position is worth ₹18,90,000. One third is ₹6,30,000, and 2% of that is ₹12,600, a fraction of what two naked futures would attract.

There is a catch on timing. For index futures, calendar spread treatment lasts only until the day before the near-month expiry, so the contract expiring that day is not counted as part of a spread. For stock futures, the treatment runs until the near-month contract expires.

Why deep out-of-the-money sellers pay more

Intuitively, a far-away strike feels safer. It usually is, on most days. The problem is what happens on the rare day it isn’t.

A deep out-of-the-money short option is cheap to sell and often expires worthless, which tempts traders to sell lots of them. When a genuine tail event hits, those far strikes can go from almost nothing to deep in the money in a session, and the losses are a large multiple of the premium collected. A position that looks small on the premium line is enormous on the risk line. The higher ELM, 3% for indices and 5.25% for single stocks, is the clearing corporation pricing in that asymmetry.

Cheap premium is not the same as low risk. The margin system knows this, which is why the furthest strikes carry the heaviest extreme loss margin.

The expiry-day surcharge

The extra 2% on expiry day came in through NSE Clearing’s October 21, 2024 circular, which implemented a SEBI circular dated October 1, 2024 on strengthening the equity index derivatives framework. The change applied from November 20, 2024.

The rule is precise about scope. It covers all short index options open at the start of the expiry day, as well as short index options opened during that day, as long as they expire that day. Options expiring on a later date are untouched. In the circular’s own table, a Nifty option expiring on November 21, 2024 carried 2% ELM on November 20 and 4% on November 21, while a contract expiring on November 28 stayed at 2% on all three days shown.

For anyone who sells options on expiry morning hoping to pocket the last bit of time decay, this is a real cost. The margin for the same trade can be meaningfully higher on expiry day than the day before, so the return on capital shrinks.

How this changes position sizing

Most traders treat margin as a number the broker shows them. It is better to treat it as information.

• Plan for the expiry-day jump. If you carry short index options into expiry, the higher ELM applies to positions open at the start of that day. Keep free cash for it, or you risk a shortfall and a forced square-off at a bad price.
• Compare stock and index trades on margin, not just view. The same rupee exposure in a single stock carries 3.5% ELM against 2% for an index. If your view is really on the market, the index trade is cheaper to hold.
• Use spreads deliberately. Calendar spreads in futures get a large ELM discount, but only while the spread treatment lasts. Watch the dates.
• Do not size by premium. For short options, size by the notional exposure, because that is what both ELM and your real risk are based on.

Margin is only one layer of protection. Daily settlement is another, and our explainer on mark-to-market covers how gains and losses move every day. If you sell straddles or strangles, our guide to the short straddle strategy shows how quickly those positions can turn. For the wider picture of stops, sizing and capital protection, see our pillar on risk management in trading.

A few practical points

NSE Clearing also uses the ELM figure at the broker level. Its margins page says a clearing member’s liquid net worth is worked out by subtracting initial margin and extreme loss margin payable from its effective deposits, and that liquid net worth must not fall below ₹50 lakh. So ELM is not only a client-level charge. It is built into how the whole chain of members keeps enough capital in the system.

Rates do change. The expiry-day surcharge, for instance, only arrived in November 2024. Before you lean on any figure in this article, check the current numbers on NSE Clearing’s margins page or your broker’s calculator. We would rather you see the live number than trust a blog post on the day it matters.

The simple takeaway: the extreme loss margin is the market’s insurance premium against the day nobody modelled. Plan for it in your capital, and it stops being a surprise.

Disclaimer: This article is for information and education only and is not investment advice. Derivatives trading carries a high risk of loss. Please do your own research or consult a SEBI-registered adviser before making any investment decision.