What is the expected move in options?

The expected move is a range: the current price plus or minus the move that option prices imply by one expiration. It comes from implied volatility (IV), the volatility that makes a pricing model match what traders actually pay for the options. When traders pay more, IV rises and the expected move widens.

It is usually read as one standard deviation. If returns followed a bell curve, about two outcomes in three would end inside ±1 standard deviation and about 95 in 100 inside ±2. Real returns do not follow a bell curve exactly, so treat those shares as the model’s assumption, not a promise.

Expected move (EM)
The size of move the options market is pricing for the underlying by one expiration, in either direction. A range, not a forecast.
One standard deviation (1 SD)
A measure of spread. Under a bell curve, about 68% of outcomes fall within ±1 SD and about 95% within ±2 SD.
At-the-money (ATM) straddle
A call and a put at the strike closest to the current price, in the same expiration. Its total price is a quick read of the move being priced.
Rule of 16
A one-day shortcut: IV ÷ 16 is roughly the one-day move in percent, because 16 is close to √252, the number of trading days in a year.

How to calculate the expected move: two common methods

Both methods work on one expiration at a time: the expected move to this Friday is not the expected move to the end of the month.

  1. The straddle shortcut. Add the mid prices of the at-the-money call and put in the expiration you care about. A $5.00 call plus a $5.00 put means the market is paying about $10.00 for movement, so the expected move reads as about ±$10 by that expiration.
  2. The implied volatility formula. Expected move ≈ price × IV × √(days to expiration ÷ 365), with the at-the-money IV of that expiration. It scales the annualized IV down to your time frame, as the implied volatility guide explains. For one session, the Rule of 16 does the same job: IV ÷ 16 gives the one-day move in percent.

Worked example: SPY’s weekly and daily expected move (hypothetical)

Hypothetical inputs: SPY at $650.00, an at-the-money IV of 16% in the expiration 7 calendar days away, and option prices from a standard pricing model with no rates or dividends. Real quotes will differ.

  1. The formula: √(7 ÷ 365) ≈ 0.1385, and $650 × 0.16 × 0.1385 ≈ $14.40. One standard deviation by expiration runs from about $635.60 to $664.40; two, ±$28.80, from about $621.20 to $678.80.
  2. The straddle: the model prices the $650 call and the $650 put at about $5.75 each, so the straddle costs about $11.49, a range of about $638.51 to $661.49.
  3. Why they differ: $11.49 ÷ $14.40 ≈ 0.80. As the straddle and strangle guide shows, an at-the-money straddle costs about 0.8 of a one-standard-deviation move, because it prices the average size of the move. Under the bell curve, about 57% of outcomes land inside ±$11.49 and about 68% inside ±$14.40.
  4. One session: 16% ÷ 16 = 1%, so about ±$6.50 for a full day, $643.50 to $656.50 (the exact √252 gives $6.55). In the same model, the 0DTE at-the-money straddle at the open costs about $5.23, again about 0.8 of that.
  5. Later in the day: the remaining move shrinks with the square root of the time left. At 2:00 p.m. ET, with 2 of 6.5 hours to go, it is about $650 × 0.16 × √(2 ÷ 6.5 ÷ 252) ≈ $3.63.

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Two cards for the same hypothetical SPY at 650.00 with 7 days left. Left, the at-the-money straddle: call 5.75 + put 5.75 = 11.49, a range of 638.51 to 661.49. Right, the implied volatility formula: 650 × 0.16 × √(7 ÷ 365) = 14.40, a range of 635.60 to 664.40. Below: 11.49 ÷ 14.40 ≈ 0.80, so the straddle is about 0.8 of one standard deviation.

How day traders use the expected move for 0DTE and weekly ranges

The expected move is context: how big a day or a week the options market is paying for, not where price will go. Day traders use the daily number; swing trades and Friday expirations use the weekly one. Common uses:

  • Mark the day’s range at the open. Draw the expected move above and below the opening price, or the prior close, next to your usual levels. A target far outside it needs a bigger day than the market is pricing.
  • Check strikes against it. An out-of-the-money 0DTE option whose strike sits beyond the expected move needs more than the priced move just to finish in the money; see how to choose a strike price. Option sellers watch the same lines from the other side, where being wrong can cost far more than the premium collected.
  • Read the edges with care. If price reaches an edge by late morning, the day has already moved what was priced. That alone is no reversal signal: trend days run straight through. Treat the line as a level to watch, with your usual confirmation and stop.
  • Watch the clock. The remaining move shrinks through the day, so a late target needs a fast move, and the option loses value while you wait; see 0DTE theta decay.

A day-trading plan checked against the expected move (hypothetical)

Same inputs: SPY opens at $650.00 and the day’s expected move is ±$6.50, so the lines sit at $643.50 and $656.50. At 10:15 a.m. ET a 5-minute candle closes above the opening range and sets up a long.

  1. Entry $651.00, stop $649.80 under the opening range: risk $1.20 a share.
  2. Target $653.40, twice the risk above the entry: reward $2.40, or 2R. It needs $3.40 from the open, about half the day’s expected move: a normal day, not an exceptional one.
  3. Size: a $30,000 account risking 0.5% accepts $150. $150 ÷ $1.20 = 125 shares. With an option instead, size from the premium you could lose, as shown in how to set a stop loss on options.
  4. The comparison: a 0DTE $660 call bought at the open needs SPY up $10.00 just to reach its strike, about 1.5 times the expected move. That is a bet on an unusual day, with the whole premium at risk.

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A hypothetical 5-minute SPY chart that opens at 650.00. Dashed lines mark the day’s expected move from the open: 656.50 above and 643.50 below, ±6.50 by the Rule of 16. A long plan sits inside it: entry 651.00, stop 649.80 and target 653.40, labeled 2R. Above the upper line, a dotted line at 660.00 reads 0DTE $660 call strike: +10.00 from the open, about 1.5 × the expected move.

The expected move around earnings and economic data

For a stock, the biggest scheduled move is usually earnings. Traders read the at-the-money straddle in the first expiration after the report as the implied move; the earnings season guide works through an example. Most of that premium is for one night, so IV often collapses after the report, and a buyer can be right on direction and still lose.

Index options react to the economic calendar instead. On CPI, jobs-report or Fed days, the expiration that contains the release carries a larger expected move than on a quiet day. Compare like with like: a CPI-day expected move against other CPI days, not against a sleepy Monday.

Limits: not a forecast, and the tails are fat

The expected move is the market’s price for movement, not a measurement of what will happen. Keep these limits in mind:

  • No direction. The range runs both ways, and nothing in it says which side is more likely.
  • Not a wall. Even under the model, about one outcome in three ends outside ±1 SD. Real markets produce large moves more often than a bell curve suggests: the tails are fat, so moves of 2 or 3 SD come along more often than the model implies.
  • It changes. IV moves during the day and between days, so the expected move you marked at the open can be out of date by noon.
  • Conventions differ. Data sites show the straddle as is, 85% of it or the IV figure, for different expirations, and wide bid-ask spreads blur the straddle. Know which number you are reading.
  • Check it against reality. Log the expected move and the actual move for the days you trade in your trading journal, and you will see how often each kind of day breaks it.