What is the thirty-day scale in this example?
Reveal the worked answer
About 7.167 dollars.
Its statistical interpretation still depends on stated assumptions.
Advanced Options · ADV-24 · Core
Expected move
What does an option-implied movement estimate mean?
What you will learn and prerequisites
- Explain the mechanism in the lesson question.
- Reproduce the worked comparison and recognize its failure case.
Read first: Read a contract and its premium, Rights, obligations and expiration, Defined payoff risk is not margin, Read the whole multi-leg ticket
An expected-move display needs a declared method. A volatility-based standard-deviation approximation, an ATM straddle premium and a percentile interval are not automatically the same statistic.
No displayed band is a boundary that price cannot cross.
Understand the mechanism
For a simple short-horizon approximation, S×sigma×sqrt(T) gives a dollar scale associated with volatility. A lognormal model has asymmetric price quantiles after exponentiation, and probabilities require explicit distribution and drift assumptions.
An ATM straddle reflects risk-neutral option pricing, carry and the shape of the payoff; it is not universally one physical-world standard deviation.
Walk through the process
Read the method, day count, expiry and IV source. Compare a directional forecast with the amount priced, while allowing jumps, skew and model error. Do not claim a certain probability for any arbitrary expected-move line.
For spread selection, crossing a band must remain a possible adverse branch.
Model and implementation boundary
These are complete fictional reading examples, not live opportunities. Terminal identities assume the stated common settlement. Multi-expiry values require a surviving-leg model. Costs, assignment and financing can alter realized outcomes; a mathematical bound alone does not guarantee the same operational loss path.
A worked example
At fictional spot100, IV 25% and thirty calendar days, the simple scale is 100×0.25×sqrt(30/365)=7.167277. The linear band 100±7.167277 is only a rough volatility scale under these assumptions.
The graph varies maturity at fixed IV. The widening curve is not a future stock path or a guaranteed confidence interval.
Open the calculation without leaving this lesson
Expected move—worked comparison
Vertical: Approximate movement scale (USD)
Horizontal: Calendar days remaining
1. Fictional example
Read the graph as a data table
| Calendar days remaining | Fictional example |
|---|---|
| 1 | 1.30856 |
| 3 | 2.26649 |
| 7 | 3.46212 |
| 14 | 4.89618 |
| 30 | 7.16728 |
| 60 | 10.1361 |
| 90 | 12.4141 |
What would invalidate the reading?
Using a displayed expected move as a guaranteed range can make short-wing risk look smaller than it is. Mixing trading and calendar days changes the scale.
Check your understanding
Try the question before revealing its answer. These are reading checks, not trading certification or a site completion record.
What is the critical failure to avoid?
Reveal the worked answer
Using a displayed expected move as a guaranteed range can make short-wing risk look smaller than it is. Mixing trading and calendar days changes the scale.
Explain this risk before treating the example as a decision rule. A correct calculation does not guarantee a favorable market outcome.
Return to the question: What does an option-implied movement estimate mean? State the observed facts, the assumptions and the failure condition separately.
Sources, assumptions and downloadable script
External references support definitions and conventions. Worked scenarios and prose are original. No current quotes or dealer inventory are claimed.
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