The range price is expected to stay within, with 68% probability.
What this universe is
The Expected Move (Expected Move, one standard deviation) is the range inside which the options market prices the underlying staying until a given expiry, with about 68% probability. It comes straight from implied volatility. It is the market's own forecast, made with real money, not an analyst's opinion.
The simple calculation
The common approximation: price × implied volatility × the square root of (days/365). A stock at $100 with annual implied volatility of 30% has a monthly range of about ±$8.6. There is a faster way: the at-the-money straddle premium for the same expiry comes close to the range directly, since the market computes it for you in the prices of two contracts.
Its three uses
Structure design: condor wings are built outside the range so probability works for the seller. Realistic targets: a target several times beyond the range needs an exceptional reason. An event scale: comparing the range priced before earnings with the average historical move shows whether the insurance is expensive or cheap.
Hypothetical example
A stock prices a ±7% range for earnings week, while its average historical move after announcements is ±4.5%. The market is paying for a bigger move than usual. That is a premium-selling setup, since history suggests less will happen than was priced. The reverse (priced below history) makes buying the move cheaper.
Common mistake
Reading it as a sacred ceiling and floor: it is a 68% range, which means that price landing outside it is expected about a third of the time by definition, and real tails are fatter than the normal distribution's anyway. Its bounds are a probability estimate, not walls.
Why it is a 68% range and not a sacred ceiling
Price is expected to land outside it about a third of the time, by definition, and real market tails are fatter than the normal distribution's. Anyone who treated it as a wall got surprised twice: by the breach, and by its size.
Where to see it on the platform
The symbol card shows its expected move for near expiries, and the calculator derives it for any expiry from its options chain.
The symbol card shows it for near expiries, and the calculator derives it directly from the options chain.
