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Expected Move

The one calculation that turns a volatility percentage into a number you can trade around.

Quick answer: Expected move is the one-standard-deviation price range that an option's implied volatility is pricing over a chosen number of days, computed as spot × implied volatility × √(days ÷ 365), and it is a price the market is charging rather than a forecast it is making.

In simple words

Implied volatility is quoted as an annual percentage, which is almost useless at the trading desk — nobody holds a weekly option for a year. Expected move translates that annual figure into the language you actually think in: how many points, over the next few days, is this option pricing? With NIFTY at 24,000, implied volatility at 13% and seven days to expiry, the expected move is 24,000 × 0.13 × √(7 ÷ 365) ≈ 432 points. That single number says the option market is charging as though NIFTY has about a two-in-three chance of finishing the week somewhere between 23,568 and 24,432.

There is a shortcut every floor trader knows. The expected move for an expiry is roughly the at-the-money straddle price multiplied by 1.25. On our seven-day NIFTY, the 24,000 straddle costs about ₹345, and ₹345 × 1.25 ≈ 431 — the same 432 we got the long way. So if you can read a straddle price off the screen, you can read the market's expected move without a calculator. The straddle is the expected move, wearing a rupee sign.

Not to be confused with: Expected profit. The expected move is a range of prices, symmetric around spot, that says nothing about which side is more likely or whether any position on it makes money. A trader who sells a strangle just outside the expected move is not collecting a statistical edge; the option market has already priced that band, and the premium is the compensation for the one expiry in three that closes outside it.

The expected move as a price band around spot

One volatility, one horizon, one band

The 1σ expected-move band for NIFTY at 24,000, drawn from the at-the-money implied volatility as days to expiry shrink.

−1σ23,568spot24,000+1σ24,432−2σ23,136+2σ24,864±1σ · 68.3%±2σ · 95.4%±3σ · 99.7%NIFTY at expiry, 7 days away · spot 24,000 · IV 13%
The band narrows with the square root of time, not linearly — halving the days remaining shrinks the expected move by about 29%, not 50%. That square-root shape is the single most important fact about how option ranges collapse into expiry, and it is why the last week decays a position far faster than the first.

Professional explanation

Why 365 and not 252

Volatility itself is annualised on 252 trading days, because volatility is generated only on days the market is open — a weekend produces no return. But the expected move uses calendar days over 365, and the reason is subtle: an option expires on a fixed calendar date, and the √(days ÷ 365) term is undoing exactly the annualisation that produced the quoted volatility. When implied volatility is quoted as an annual figure, that figure already assumes a full 365-day year has been compressed into the number. To scale it down to a seven-day horizon you divide by the same 365. Mixing the two conventions — annualising on 252 but scaling the move on 252 as well — double-counts the calendar and inflates the band. The clean rule is: 252 lives inside the volatility figure, 365 lives inside the time-scaling of the move.

The straddle shortcut, and why the multiplier is 1.25

An at-the-money option is worth approximately 0.4 × S × σ × √T, an identity that falls out of the Black–Scholes formula when the strike equals the spot. A straddle is a call plus a put at the same strike, so it is worth roughly 0.8 × S × σ × √T. The expected move — the 1σ figure — is S × σ × √T with no 0.4 in front. Divide one by the other and the S, the σ and the √T all cancel, leaving 1 ÷ 0.8 = 1.25. That is the whole derivation: the expected move is 1.25 times the straddle because a straddle is 0.8 of a standard deviation, priced. This is the Brenner–Subrahmanyam approximation rearranged, and it is why a trader can glance at a ₹345 straddle and say '430-odd points' without touching a formula.

The band is symmetric; the world is not

The expected-move calculation places the band symmetrically around spot — the same number of points up as down. Equity index returns are not symmetric. NIFTY falls faster than it rises, the left tail is fatter than the right, and the volatility skew is the option market's acknowledgement of exactly this. So the true probability of touching the lower edge of a NIFTY expected-move band is higher than the probability of touching the upper edge, even though the calculation draws them the same distance apart. A trader who treats the band as a symmetric bet is quietly short the crash that the skew has already priced. The symmetric band is a convenience of the lognormal model, not a claim about the market.

Straddle versus ATM implied volatility — two answers, and which to trust

There are two ways to compute an expected move and they rarely agree exactly. One feeds the at-the-money implied volatility into S × σ × √T. The other reads the straddle price off the screen and multiplies by 1.25. They differ because the 0.4 and 0.8 coefficients are first-order approximations that drift as an option moves in time and because the straddle price embeds the skew and the cost of the wings, while a single at-the-money volatility does not. The straddle-based figure is the one the market will actually transact at — it is a live price, not a model output — so when the two disagree, trust the straddle for anything you intend to trade and trust the volatility-based figure for anything you intend to compare across dates. The uncomfortable truth is that both are estimates, and neither is the move that will actually happen.

68, 95, 99.7 — but only if the world were normal

The 1σ, 2σ and 3σ expected-move bands around NIFTY 24,000 for a 30-day horizon.

mean24,000−1σ23,106+1σ24,894−2σ22,211+2σ25,789−3σ21,317+3σ26,683±1σ · 68.3%±2σ · 95.4%±3σ · 99.7%NIFTY level 30 days from a spot of 24,000, at 13% implied volatility
The 1σ band captures about 68% of outcomes and the 2σ band about 95% — under the normal-distribution assumption baked into the calculation. Real index returns have fatter tails, so the outer bands are breached more often than these percentages promise. The picture is a useful map, not the territory.

Formula

The expected move at one standard deviation

EM(1σ) = S × σ × √(days ÷ 365)

The result is in the same units as S — index points for NIFTY, rupees for a stock. Multiply by 2 for the 2σ (≈95%) band or by 3 for the 3σ (≈99.7%) band. The days ÷ 365 uses calendar days because the option expires on a calendar date; the 252-day convention lives inside σ, not here.

  • EM(1σ)The one-standard-deviation expected move, in points or rupees, either side of spot.
  • SSpot price of the underlying — 24,000 for NIFTY, 52,000 for BANKNIFTY in the examples on this site.
  • σImplied volatility, annualised, expressed as a decimal (0.13 = 13%). Use the at-the-money near-expiry value.
  • daysCalendar days to expiry, counted from now to the expiry date inclusive of weekends.
  • 365Calendar days in a year — the denominator that scales an annual volatility down to the option's actual horizon.

The trading-floor straddle shortcut

EM ≈ ATM straddle price × 1.25

Because an at-the-money straddle is worth about 0.8 × S × σ × √T and the expected move is S × σ × √T, their ratio is 1 ÷ 0.8 = 1.25. This lets a trader read the expected move straight off a straddle quote with no calculator and no implied-volatility figure at all.

How to compute an expected move

  1. Take the underlying's spot price and the at-the-money implied volatility of the expiry you care about. For a screener that only shows India VIX, that figure is already a 30-day at-the-money proxy for NIFTY.
  2. Count the calendar days to expiry, weekends included, and divide by 365.
  3. Take the square root of that fraction and multiply by spot and by the implied volatility as a decimal. The result is the 1σ expected move in points.
  4. Add and subtract it from spot to get the band. This is the range the market prices at roughly 68% odds.
  5. Cross-check it against the market directly: read the at-the-money straddle price and multiply by 1.25. If the two answers are far apart, the implied volatility you used is stale or off the money.
  6. For a wider or narrower confidence band, scale: multiply the 1σ move by 2 for about 95% coverage, but remember the tails run fatter than the normal model claims, so the outer bands break more often than the percentages suggest.

Practical example

NIFTY worked example

NIFTY is at 24,000, seven days remain to weekly expiry, and the at-the-money implied volatility is 13%. The expected move is 24,000 × 0.13 × √(7 ÷ 365) = 24,000 × 0.13 × 0.1385 ≈ 432 points. Cross-check with the straddle: the 24,000 call and put together cost about ₹345, and ₹345 × 1.25 ≈ 431 — the same number by a completely different route. Now interpret it. The market is pricing about a 68% chance NIFTY expires between 23,568 and 24,432, a 95% chance it stays inside roughly ±864 points, and — this is the part beginners skip — about a one-in-three chance it closes outside the 1σ band entirely. That last outcome is not the forecast failing. The band was never a forecast. It is the price of a bet, and a bet with two-in-three odds is supposed to lose one time in three.

BANKNIFTY worked example

BANKNIFTY at 52,000 with a 14% implied volatility and seven days left prices an expected move of 52,000 × 0.14 × √(7 ÷ 365) ≈ 1,008 points, more than double NIFTY's in absolute terms. The lesson BANKNIFTY teaches is what happens on expiry morning. With one day to go, the same 14% implies a move of only about 381 points — the √(days) term has collapsed the band by more than half in a week. Traders who sold a strangle 700 points wide on Monday, comfortably outside the expected move, watch that same 700-point cushion become enormous relative to a shrinking band by Thursday. The expected move does not decay evenly; it decays with the square root of time, so the last day sheds the most range of any single session. Selling range and buying it back are not mirror-image trades across the week.

Lot sizes used above (NIFTY 75, BANKNIFTY 30) are those in force at the time of writing; NSE revises them periodically. Figures exclude brokerage, STT, exchange charges, stamp duty and GST. Examples are teaching scenarios built on round numbers — they are not historical quotes, not backtests and not trade calls.

Risk note. The expected move is routinely used to justify selling options 'outside the range', on the reasoning that the market rarely travels that far. It travels that far one expiry in three at 1σ, by construction, and when it does the loss on a short strangle can dwarf the premium collected. The band describes the centre of the distribution well and the tail badly, and it is the tail that closes accounts. An expected move is a map of where the market usually goes, sold to you by the people who profit when it goes somewhere else.

Advantages & limitations

What it is good for

  • It converts an abstract volatility percentage into concrete points or rupees, which is the form a trader can actually place strikes, stops and targets around.
  • It requires nothing but spot, an implied volatility and a day count — no option-pricing model, no software, no chain. It can be done on the back of an envelope.
  • The straddle shortcut lets you read it straight off a live market price, so it reflects what the market will genuinely transact at rather than a model's opinion.
  • It scales cleanly across horizons and confidence levels: the same √(days) machinery gives you a one-day move, a weekly move and a 2σ band from a single number.
  • It is the honest denominator for judging any range-based trade. Comparing your break-even width to the expected move tells you immediately whether you are selling inside or outside what the market has already priced.

Where it breaks down

  • It assumes a lognormal, symmetric distribution of returns. Real index returns are skewed and fat-tailed, so the downside edge of a NIFTY band is touched more often than the upside, and both outer bands are breached more often than the normal percentages promise.
  • It uses a single at-the-money implied volatility, which ignores the skew entirely. The true distribution of outcomes is wider in the left tail than a single volatility figure can express.
  • It is only as current as the implied volatility fed into it. Near expiry, when the at-the-money premium is tiny, a small change in the quote produces a large swing in the implied volatility and therefore in the computed move.
  • It says nothing about path. Two markets can both finish exactly on the expected-move edge, one drifting there calmly and one crashing through it and rebounding — and those two paths destroy or reward a gamma position completely differently.
  • The 1.25 straddle multiplier is a first-order approximation. It holds well for near-the-money, near-dated options and degrades for long-dated ones, where the 0.4 coefficient itself drifts.
  • It is a one-standard-deviation figure by default, which people read as 'the range', when it is explicitly the range the market expects to be wrong about a third of the time.

Common mistakes

  • Reading the expected move as a prediction that the market will stay inside the band. The band is a 68% region by construction; expecting it to hold every expiry is expecting a two-thirds probability to behave like a certainty, and the surprise arrives on schedule.
  • Using 252 in the time-scaling instead of 365. Volatility is annualised on 252 trading days, but the move is scaled on 365 calendar days because the option expires on a calendar date. Using 252 in both places double-counts and inflates the band by about 20%.
  • Selling strangles just outside the expected move and calling it an edge. The option market has already priced that band; the premium is the fair compensation for the tail, not a mispricing you have discovered, and short strangles carry open-ended loss.
  • Confusing the expected move with expected profit. The expected move is a symmetric range of prices; it contains no information about which position on that range makes money, and it certainly does not promise any.
  • Ignoring the skew and treating the band as symmetric. On NIFTY the downside edge is genuinely more likely to be reached than the upside edge, because the put skew is pricing exactly that asymmetry.
  • Recomputing the expected move from a stale or off-the-money implied volatility near expiry and building a trade on the result, when the premium the volatility was extracted from has already decayed toward zero.
  • Comparing the expected move of two different underlyings in raw points. BANKNIFTY's 1,008-point move being larger than NIFTY's 432 does not make BANKNIFTY 'more volatile' in a comparable sense until you divide each by its own spot.

Professional usage

Options desks quote and hedge in terms of the expected move constantly, though they rarely call it that. A market maker running a gamma book thinks of the day's expected move as the break-even amount of underlying movement — realise more than the straddle implies and a long-gamma position pays for its theta, realise less and it bleeds. Event desks build the entire earnings and event trade around it: the implied move ahead of an RBI policy decision or a Union Budget is compared against the average move those events have historically produced, and the trade is a bet on that difference, delta-hedged so the outcome depends on realised versus implied range rather than direction. The straddle-times-1.25 rule is the number a trader carries in their head to sanity-check every strike they quote.

Risk and margin systems use the expected move as the natural unit of a stress scenario. A 1σ or 2σ shock is not an arbitrary percentage move; it is the move the live option surface is currently pricing, which means the stress test updates itself as the market's own fear updates. Portfolio hedgers size protection against it too: buying puts one expected move below spot is a very different cost and a very different level of coverage from buying them two moves down, and framing the choice in expected-move units rather than fixed percentages keeps the hedge calibrated to current volatility instead of to a number chosen in a calmer month.

Key takeaways

  • The expected move is spot × implied volatility × √(days ÷ 365) — the 1σ price band the option market is charging for, in the same units as the underlying.
  • Use 365 calendar days in the time-scaling, not 252. The 252-day convention already lives inside the annualised volatility figure.
  • The expected move is about 1.25 times the at-the-money straddle price, because a straddle is worth roughly 0.8 of a standard deviation — so you can read the move straight off a straddle quote.
  • It is a price, not a prediction. The 1σ band is designed to be breached about one expiry in three, and that breach is the band working as intended, not failing.
  • The band is drawn symmetrically, but index returns are skewed, so the downside edge is genuinely more likely to be reached than the upside edge.

Learn to compute an expected move in your head and every implied volatility on the screen suddenly means something you can act on: a range, in points, over the days you actually hold the option. But hold on to what the number is not. It is not a forecast, it is not a boundary the market has promised to respect, and it is not an edge waiting to be sold. It is the price of a bet the market has already made, and the whole reason it is worth knowing is so you can decide whether that price is one you want to take the other side of.

Frequently asked questions

What is the expected move in options?
The expected move is the one-standard-deviation price range an option's implied volatility is pricing over a chosen number of days, computed as spot × implied volatility × √(days ÷ 365). With NIFTY at 24,000, 13% implied volatility and seven days left it is about 432 points, meaning the market prices roughly 68% odds of finishing between 23,568 and 24,432.
How do you calculate the expected move?
Multiply the spot price by the annualised implied volatility as a decimal, then by the square root of days divided by 365. For NIFTY at 24,000 with 13% volatility over seven days: 24,000 × 0.13 × √(7 ÷ 365) ≈ 432 points. That is the 1σ move; double it for a roughly 95% band.
Why do you use 365 days instead of 252 for the expected move?
Because the option expires on a calendar date and the √(days ÷ 365) term scales the annual volatility down to that horizon, undoing the same 365-based annualisation. The 252 trading-day convention already lives inside the quoted volatility figure. Using 252 in both places double-counts the calendar and inflates the band by about a fifth.
What is the straddle shortcut for the expected move?
The expected move is approximately the at-the-money straddle price multiplied by 1.25. A NIFTY 24,000 straddle at ₹345 implies a move of about ₹345 × 1.25 ≈ 431 points, matching the formula. The multiplier is 1.25 because a straddle is worth roughly 0.8 of a standard deviation.
Why is the straddle multiplier exactly 1.25?
An at-the-money option is worth about 0.4 × spot × volatility × √time, so a straddle — a call plus a put — is worth about 0.8 of that product. The 1σ expected move is the same product with no coefficient, so the ratio is 1 ÷ 0.8 = 1.25. The spot, volatility and time all cancel, leaving a pure number.
Is the expected move a prediction of where the market will go?
No. It is a price the option market is charging for a range, not a forecast that the range will hold. The 1σ band is designed to be breached about one expiry in three, so a close outside it is the band behaving exactly as constructed, not a prediction that failed.
What does 1σ, 2σ and 3σ mean for the expected move?
They are widening confidence bands: the 1σ move covers about 68% of outcomes, 2σ about 95% and 3σ about 99.7% — under a normal distribution. Multiply the 1σ figure by two or three to get them. In real markets the fat tails mean the outer bands break more often than those percentages promise.
How often does the market close outside the expected move?
At 1σ, about one expiry in three, by construction, because a one-standard-deviation band captures roughly 68% of a normal distribution. Because index returns have fatter tails than normal, the outer bands are breached somewhat more often than the textbook 5% and 0.3% figures suggest.
Is the expected move the same as expected profit?
No, and confusing the two is a costly error. The expected move is a symmetric range of prices around spot; it contains no information about which side is more likely or whether any position makes money. A strike sold outside the expected move earns premium precisely because the tail beyond it is real.
Does the expected move account for the volatility skew?
Not when computed from a single at-the-money implied volatility — that version is symmetric. The real distribution on an index is skewed, so the downside edge of a NIFTY band is more likely to be touched than the upside edge. The straddle-based figure captures a little of the skew because a straddle price embeds the wings.
Should I use the straddle price or the ATM implied volatility for the expected move?
Use the straddle for anything you intend to trade, because it is a live price the market will transact at, and use the implied-volatility figure for comparing across expiries or underlyings. When they disagree, the volatility you used is probably stale or off the money.
How does the expected move change as expiry approaches?
It shrinks with the square root of the days remaining, not linearly. Halving the days left cuts the move by about 29%, not 50%, and the final session sheds more range than any earlier one. A 432-point weekly NIFTY move collapses to about 163 points with one day left.
What is the expected move for NIFTY on expiry day?
With one calendar day to expiry and a 13% implied volatility, the NIFTY expected move is 24,000 × 0.13 × √(1 ÷ 365) ≈ 163 points. The square-root-of-time collapse means expiry-day ranges are a fraction of the weekly range, which is why gamma and theta both spike in the final session.
Can I use India VIX to compute the expected move?
Yes, as a 30-day NIFTY proxy. India VIX is an annualised at-the-money-equivalent volatility over a constant 30-day horizon, so 24,000 × (VIX ÷ 100) × √(30 ÷ 365) gives the monthly expected move. For a different horizon, rescale the days term rather than the VIX figure.
Why does BANKNIFTY have a larger expected move than NIFTY?
Partly because its spot is higher — 52,000 versus 24,000 — and partly because it genuinely realises more volatility as a concentrated banking index. In raw points BANKNIFTY's move dwarfs NIFTY's, but dividing each by its own spot shows the gap is smaller in percentage terms than the point figures suggest.
Does the expected move tell me anything about direction?
No. It is symmetric by construction and sign-agnostic. A 432-point expected move is equally a statement about a rally and a sell-off. Any directional read has to come from elsewhere — the skew hints that the downside is heavier, but the expected-move number itself is direction-blind.
How is the expected move used to place option strikes?
Traders frame strikes in expected-move units: a strangle sold at the 1σ edges collects the premium for a band the market breaches about a third of the time, while strikes at 2σ collect less for a wider cushion. Framing strikes this way keeps them calibrated to current volatility rather than to fixed point distances.
Why does the expected move decay with the square root of time?
Because volatility scales with the square root of time — variance adds linearly across independent days, and volatility is the square root of variance. So a four-times-longer horizon produces only a two-times-larger move. This is the same √t law that governs every volatility calculation.
Is the expected move affected by interest rates?
Only marginally. The core formula uses spot, volatility and time and ignores the risk-free rate, which for a short-dated Indian index option shifts the forward by a small amount. For weekly expiries the rate's effect on the expected move is negligible against the volatility term.
What implied volatility should I use for the expected move?
The at-the-money implied volatility of the specific expiry you are measuring, because at-the-money is the most liquid strike and carries the most vega. Using an off-the-money volatility from the skew will give a move that is too wide or too narrow for the centre of the distribution.
Can the expected move be wrong?
It is not the kind of thing that is right or wrong — it is a price, not a forecast. The realised move will differ from it almost every time, sometimes by a lot, and that difference is exactly what a volatility trade is a bet on. The volatility risk premium exists because implied moves tend to run slightly larger than realised ones.
How does the expected move relate to a strangle's break-even?
Directly: comparing the width of a strangle's break-even to the expected move tells you whether you are selling inside or outside what the market has priced. Selling break-evens narrower than the expected move means collecting premium on a band the market expects to be breached, which is not the free lunch it can appear to be.

Voice search & related questions

Natural-language questions people ask about expected move.

What does the expected move actually mean?
It means the option market is charging as though the underlying has about a two-in-three chance of finishing within that many points of where it is now. For NIFTY at 24,000 with a week to go, that band is roughly 432 points wide either side — a price for a range, not a promise about it.
How do I quickly work out the expected move without a calculator?
Read the at-the-money straddle price off the screen and multiply by 1.25. A ₹345 NIFTY straddle gives about 431 points, the same answer the full formula produces. It works because a straddle is worth roughly 0.8 of a standard deviation, and 1 ÷ 0.8 is 1.25.
Why does the market often close outside the expected move?
Because the 1σ expected move is only supposed to hold about 68% of the time — roughly two expiries in three. Closing outside it the other third of the time is the band doing its job, not breaking. People treat a two-thirds probability as if it were a wall, and it never was one.
Can I make money selling options outside the expected move?
You can collect premium there, but it is not a free edge — the market has already priced that band, and the premium is fair compensation for the times price travels past it. Short strangles carry open-ended loss, and the tail beyond the expected move is exactly where accounts get emptied. Nothing here is investment advice.
Does a bigger expected move mean the market will crash?
No — it just means options are charging for a wider range, in either direction. The expected move is symmetric and says nothing about which way price goes. The skew hints the downside is a little heavier on an index, but the move number itself is completely direction-blind.
Why does the expected move shrink so fast near expiry?
Because it scales with the square root of time, so the last day loses more range than any earlier day. A weekly move of 432 points on NIFTY falls to about 163 with one day left. That collapse is why the final session is where gamma and theta both get violent.
Is the expected move the same for NIFTY and BANKNIFTY?
No — BANKNIFTY's is far larger in points, around 1,008 versus NIFTY's 432 for a week, because its spot is higher and it genuinely moves more. But in percentage-of-spot terms the two are closer than the raw point figures make them look, so always divide by spot before comparing.

Sources & references

Last reviewed 10 July 2026. Educational content only — not investment advice.

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