Volatility Surface

Q: What is the volatility surface?

The volatility surface is the complete set of implied volatilities for one underlying, arranged by strike along one axis and by expiry along the other. Each option on the chain is one point on it. Slicing the surface at a single expiry gives the volatility smile; slicing it at a single strike gives the term structure. It is the market's full statement of how much movement it expects, in which direction, over which horizon.

Q: What does a normal NIFTY volatility surface look like?

In a calm market, implied volatility is lowest near the money, rises steeply toward lower strikes and gently toward higher ones, and that curvature is sharpest on the nearest expiry and flattens for later ones. Along the expiry axis, at-the-money volatility usually rises with time, so the surface tilts upward toward far expiries. Stress inverts the term structure, lifting near expiries above far ones, and steepens the put side everywhere.

Q: Why do I need the whole surface instead of one implied volatility?

Because every strike and expiry has its own number, and any position spanning more than one of them is priced off more than one point. A spread, a calendar, a hedge rolled to a later expiry, or a position whose delta moves it toward a different strike all depend on the surface's shape, not on a single at-the-money figure. Risk measured at one point misses how the surface itself moves.

Q: How does the surface change around an event?

Before a scheduled event such as an RBI decision or the Union Budget, the expiry that contains the event lifts relative to the ones before and after it, producing a bump in the term structure at that date. The put side steepens on that expiry. After the event the bump collapses in a session, which is the implied volatility crush, while expiries further out move much less.

Q: Can the surface be read from the option chain?

Yes, one expiry at a time. The IV column of the chain for a given expiry is one slice of the surface across strikes; switching expiry gives the next slice. Comparing the at-the-money IV across those slices gives the term structure. Platforms that plot the grid as a heat map or a three-dimensional surface are drawing the same numbers.

The smile across strikes and the term structure across expiries are two views of one object. The surface is the whole thing: every implied volatility the market is quoting, laid out so its shape can be read.

In short: the volatility surface is the grid of implied volatility for one underlying across every strike and every expiry. Cut it at one expiry and you get the volatility smile; cut it at one strike and you get the term structure. On NIFTY the surface is normally lowest near the money, steeper on the put side, sharpest on the nearest expiry and gently rising toward later ones. Its shape, and how that shape changes, is the market's most complete expression of what it fears and when.

The intuition

A single implied volatility answers one question: how much movement does the market price for this strike, to this date? The chain asks that question hundreds of times, once per contract. The surface is simply all the answers at once. Its two axes carry different information. Across strikes, the shape says in which direction the market expects the large moves, and how large. Across expiries, it says when. A trader who looks only at the at-the-money IV of the nearest weekly is reading one cell of the grid.

The surface is not flat because the world is not the one the pricing model assumes. If it were, every cell would hold the same number. The departures from flat are the market's corrections: more volatility for puts than calls because indices fall faster than they rise, more for near expiries in stress and for far expiries in calm, a bump at any expiry that contains a known event.

Worked reading (illustrative numbers)

Suppose NIFTY is at 24,000 and the chain shows the following implied volatilities across three expiries, with an RBI policy decision falling inside the 27-day window:

Strike	6 days (weekly)	27 days (monthly)	62 days
23,000	21.0%	19.0%	17.5%
23,500	17.5%	16.5%	15.8%
24,000	13.5%	14.0%	14.5%
24,500	12.0%	12.5%	13.4%
25,000	11.8%	12.0%	12.8%

Read it both ways. Down each column is a smile: steep on the put side, gentle on the call side, and most curved on the 6-day expiry, where the 23,000 put carries 7.5 points more than the at-the-money against 3 points on the 62-day. Across the at-the-money row is the term structure: 13.5%, 14.0%, 14.5%, rising with time, which is the normal calm-market shape. The monthly sits slightly above a straight interpolation between the weekly and the 62-day because the policy decision sits inside it; that half-point bump is the event's price. After the decision, expect the 27-day column to drop toward the line and the other two to barely move.

The surface as a heat map. Darker is higher implied volatility. Each column is a smile; each row is a term structure.

Why it matters to an options trader

Every multi-leg position is priced off it. A calendar trades two points on the same row; a put spread trades two on the same column; a diagonal trades two on neither. Their value depends on the shape between the points.
It shows where the market is paying up. A cell that sits above its neighbours is a contract the market wants; selling it collects that demand, buying it pays for it.
It locates events. A bump at one expiry is a scheduled event; a steepening of the whole put side is unscheduled fear.
It is what moves when "volatility" moves. India VIX summarises the 30-day at-the-money region; the surface shows whether a VIX move came from the near expiry, the far, the wings or everywhere.

Common mistakes

Pricing a far strike or far expiry at the at-the-money weekly IV. It will be wrong by several points in a predictable direction.
Treating the surface as fixed when running a scenario. A 500-point fall does not leave implied volatility where it was; the whole surface rises and the put side steepens. A scenario that moves spot alone understates the loss on short puts.
Reading far-expiry cells as precise. Beyond the next monthly, NIFTY strikes away from the money trade thinly and their IV is often a stale print; the surface there is an interpolation.
Confusing a term-structure inversion with a smile change. Near IV above far IV is a statement about time; a steeper put side is a statement about direction. Stress usually brings both, but they can occur separately.
Forgetting that the surface is quoted in the model's units. Implied volatility is a Black-Scholes input; the surface's shape is a map of where that model's assumptions fail, not an independent fact.

Indian-market specifics

On NIFTY the surface has fine resolution along the expiry axis in the near term, with weekly Tuesday expiries, and coarse resolution beyond, with monthly and quarterly contracts; Bank Nifty, FinNifty and Midcap Select have monthly expiries only since November 2024, so their surfaces have no weekly column.
NSE's chain publishes implied volatility per strike per expiry, computed from the last traded price with Black-Scholes; the published surface therefore has gaps and stale cells wherever a strike has not traded.
Recurring bumps on the Indian surface sit at the expiries containing RBI policy meetings, the Union Budget in February, and quarterly results seasons for the banking-heavy indices.
Expiry-day dynamics affect the nearest column only: on the final Tuesday the weekly's at-the-money IV becomes unstable and is best read as a straddle price rather than an annualised volatility.

FAQ

What is the volatility surface?

The grid of implied volatility by strike and expiry for one underlying; the smile and the term structure are its two slices.

What does a normal NIFTY volatility surface look like?

Lowest near the money, steep on the put side, most curved on the nearest expiry, and gently rising toward far expiries in calm markets.

Why do I need the whole surface instead of one implied volatility?

Because any position spanning strikes or expiries is priced off several points and off how the surface moves.

How does the surface change around an event?

The expiry containing the event lifts and its put side steepens; after the event that column collapses while others barely move.

Can the surface be read from the option chain?

Yes, one expiry at a time from the IV column, switching expiries for the next slice.

One slice at a time

The NIFTY option-chain page shows the implied volatility at every strike for the current expiry, which is one column of the surface. In the app, the option chain can be switched between expiries, giving the other columns, with the Greeks at each strike.

NIFTY option chain Volatility skew guide

Related terms

Volatility Smile, the surface at one expiry
Term Structure, the surface at one strike
Volatility Skew, the tilt of each smile
IV Crush, what happens to the event column afterwards