# Gamma Exposure for Nifty, Explained: How to Read GEX Source: SquawkFlow URL: https://squawkflow.com/learn/gamma-exposure-nifty-explained Category: Options Greeks Published: 2026-10-07 Type: Explainer > What gamma exposure means for Nifty options, the sign assumption every Nifty GEX number rests on, and how weekly expiry and lot sizes change the reading. --- ## The Short Answer Gamma exposure (GEX) estimates how much of the underlying index the hedging side of the options market would have to buy or sell for a given move. For Nifty, it is usually quoted in ₹ crore per 1% move in the index. A large positive number means hedging tends to lean against moves; a large negative number means hedging tends to push in the direction of the move. The concept is the same one used for the S&P 500, covered in our [complete guide to gamma exposure](/learn/what-is-gamma-exposure-gex). Three things change in India: who is assumed to be on the other side of the open interest, how the expiry calendar is built, and the units. The first one matters most, because every Nifty GEX figure you see depends on an assumption that cannot be observed strike by strike. ## What Gamma Exposure Measures Gamma is the rate at which an option's delta changes as the underlying moves. Someone who sold an option and hedges its delta has to adjust that hedge as the index moves, and gamma tells them how fast. Sum that across every strike and expiry, weight it by open interest and by the size of the index, and you get an estimate of the hedging flow a 1% move would trigger. Two regimes follow from the sign: - **Positive net GEX.** The hedging side is long gamma. When the index rises, their hedge becomes too long and they sell; when it falls, they buy. That flow leans against the move and tends to compress the range. - **Negative net GEX.** The hedging side is short gamma. When the index rises they must buy more, and when it falls they must sell more. That flow runs with the move and tends to widen it. Neither regime is a forecast. GEX describes the positioning that existed when the open interest was recorded. Other flows, news and the session itself can overwhelm it. ## A Worked Example With Synthetic Numbers The numbers below are invented to show the arithmetic. They are not Nifty data. Take a hypothetical index at 10,000 and one strike where the option's gamma is 0.0005 per index point, with 5,00,000 units of open interest (units, not lots). The usual formula is: GEX at a strike = gamma x open interest (units) x spot squared x 1% So: 0.0005 x 5,00,000 x 10,000 x 10,000 x 0.01 = ₹25,00,00,000, which is ₹25 crore per 1% move. In words: if the index moved 1%, the side hedging this one strike would need to trade roughly ₹25 crore of index exposure to stay flat. A full GEX profile repeats this for every strike and every expiry, applies a sign to each one, and adds them up. The sign is where the real judgement sits. ## The Assumption Every Nifty GEX Number Rests On Open interest tells you how many contracts exist. It does not tell you who is long and who is short at each strike. To turn open interest into gamma exposure, you have to assume who is doing the hedging. In the US, the standard convention is that dealers are long the calls the public sells them and short the puts the public buys. Under that reading, call open interest adds positive gamma for dealers and put open interest adds negative gamma, and there is usually an index level where the net total changes sign. That level is the gamma flip, explained in our [GEX flip guide](/learn/gex-flip-price-explained). In India the commonly stated view is different: retail traders are net buyers of index options, and proprietary desks and other writers sell them. If you take that view to its limit, the hedging side is short every option, every strike counts negative, and there is no flip at all. NSE's own participant-wise open interest, which splits index option positions between clients, foreign institutions, domestic institutions and proprietary traders, does not always bear the simple story out. It is also a total across all index options, not a per-strike or per-index breakdown, so it informs the assumption rather than replacing it. The practical consequence: - **Walls barely depend on the assumption.** A call wall or put wall is the strike with the largest gamma concentration. Ranking by size gives the same strikes under either reading. Our [call wall and put wall guide](/learn/call-wall-put-wall-explained) covers how to read them. - **Net GEX and the flip depend on it completely.** The same chain can read as a positive regime with a flip under one convention and as negative everywhere under the other. Any Nifty GEX source that shows a single regime without saying which convention produced it is hiding the most important input. Our [India method page](/india/method) publishes both readings and labels which one is on screen. ## How India's Contract Structure Changes the Reading ### European style, settled in cash NSE index options are European style: they can only be exercised at expiry, and exercise is automatic for in-the-money positions. Final settlement is in cash, credited or debited through clearing banks, as described in NSE Clearing's [settlement mechanism](https://www.nseclearing.in/clearing-settlement/equity-derivatives/settlement-mechanism). Nobody can exercise early to change the open interest picture, and nobody delivers the index. For GEX, this keeps the arithmetic clean: a standard European pricing model fits the contracts, and the open interest you see stays in place until expiry or until someone trades it away. ### One weekly expiry, and it is on Tuesday SEBI's circular of 1 October 2024, [Measures to strengthen Equity Index Derivatives framework](https://www.sebi.gov.in/legal/circulars/oct-2024/measures-to-strengthen-equity-index-derivatives-framework-for-increased-investor-protection-and-market-stability_87208.html), ruled that each exchange may offer weekly expiries on only one of its benchmark indices, effective 20 November 2024. On NSE that index is Nifty 50. Bank Nifty and Fin Nifty kept monthly contracts only. NSE then moved the expiry day. Its circular [NSE/FAOP/68747 of 25 June 2025](https://nsearchives.nseindia.com/content/circulars/FAOP68747.pdf) shifted Nifty weekly contracts from Thursday to Tuesday, and the monthly contracts on Nifty, Bank Nifty and Fin Nifty from the last Thursday to the last Tuesday of the month, for expiries from September 2025 onward. When the expiry day is a trading holiday, the contract expires on the previous trading day, as our [expiry calendar](/india/expiry-calendar) shows for each listed date. Why this matters for GEX: gamma for an at-the-money option grows sharply as expiry approaches. With one weekly Nifty expiry, the front series dominates the total in the final sessions before each Tuesday, and its strikes can outweigh much larger open interest further out. Reading Nifty GEX on a Monday evening is a different exercise from reading it the evening after expiry, when the front series has just rolled off. The sharpest version of this is what Indian traders call a [gamma blast](/india/gamma-blast). ### Lot sizes move, so count units The same SEBI circular requires index derivative lot sizes to be set so that contract value sits within ₹15 lakh to ₹20 lakh on the day of review. As the index level changes, the exchange revises lot sizes, and a revision applies from a given expiry. A GEX calculation should therefore work in units of the index (open interest in units, not lots), and any lot size should be read from the exchange's own file rather than remembered. Old articles quoting a fixed lot size go stale every time the exchange revises it. ## Reading the Levels Once you know which convention you are looking at, the levels read the same way they do for the S&P 500: 1. **Call wall.** The strike with the largest call gamma. Under the dealer-long-calls reading, hedging near it leans against further upside. 2. **Put wall.** The strike with the largest put gamma. Hedging there can accelerate a move through it rather than stop it, depending on the convention. 3. **Gamma flip.** The index level where net GEX changes sign. It exists only under the dealer-long-calls reading, and only if the recalculated profile actually crosses zero. If it does not, the honest answer is that there is no flip. 4. **Net GEX.** The overall size and sign, in ₹ crore per 1%. Compare it with recent sessions rather than reading it in isolation. Max pain is a separate idea: the settlement level at which option buyers would collect the least for one expiry. It is computed from open interest alone, with no gamma involved. Our [max pain explainer](/learn/max-pain-theory-options) covers what it can and cannot tell you. ## What End-of-Day GEX Cannot Tell You Open interest in India is published once a day, after the 15:30 IST close. GEX built from it describes the book traders carried out of the last session. During the next session, especially on a Tuesday expiry, positions open and close by the minute and the profile changes with them. Settlement prices for illiquid strikes are computed by the exchange rather than traded, which makes the implied volatility behind their gamma less reliable. And the sign convention is still an assumption. Treat Nifty GEX as a map of where hedging pressure was concentrated at the close, not a prediction of where the index will go. Heavy near-the-money gamma does not guarantee a large expiry-day move. ## Where SquawkFlow's Levels Stand SquawkFlow publishes US market data in the [terminal](/terminal) through the session, including S&P 500 gamma exposure computed from the full options chain and its daily settled open interest (see [SPX gamma levels](/learn/spx-gamma-levels)). For India, levels are built from the exchanges' end-of-day files and published at the [India hub](/india). Its Nifty page shows the call wall, put wall, flip and max pain for the next session under both sign conventions, and the [method page](/india/method) shows exactly how each number is computed, including the assumptions this article describes. *Educational content, not financial advice. See our [risk disclosure](/risk-disclosure).* --- ## Citation Source: SquawkFlow, https://squawkflow.com/learn/gamma-exposure-nifty-explained Retrieved: 2026-10-08 16:19 ET Attribution: cite the page URL rather than a copied number. Levels are recomputed every session, so a number without its date is wrong within a day. SquawkFlow publishes market-structure data and education. Nothing here is investment advice, a price target or a recommendation, and we have no order execution.