Expected Move Cone: Options Implied Range

Direct answer: The expected move cone is derived from implied volatility and represents the one-standard-deviation price range the market assigns for a given expiration, covering approximately a 68% probability. It is calculated as: stock price multiplied by IV multiplied by the square root of (DTE divided by 365). The cone widens with more time or higher IV and is directly related to the price of the at-the-money straddle.

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Deriving the Expected Move from Implied Volatility

Implied volatility (IV) is expressed as an annualized percentage. To convert it into a dollar expected move for a specific time horizon, you scale it down to the relevant number of calendar days using the square root of time:

Expected Move (1 SD) = Stock Price x IV x sqrt(DTE / 365)

As a hypothetical example: a stock trades at $150, has 30% implied volatility, and there are 30 days until expiration.

Step 1: Convert DTE to a fraction of a year: 30 / 365 = 0.0822
Step 2: Take the square root: sqrt(0.0822) = 0.2867
Step 3: Multiply: $150 x 0.30 x 0.2867 = approximately $12.90

This means the options market implies approximately a 68% probability that the stock will be within plus or minus $12.90 of its current $150 price (between $137.10 and $162.90) by expiration. The two-standard-deviation range (approximately 95% probability) would be roughly twice that width: between about $124.20 and $175.80.

The Visual Shape of the Cone

On a price chart, the expected move cone begins as a narrow range at the current date and expands outward to the right as time increases. The upper and lower boundaries of the one-SD cone diverge at a rate determined by IV multiplied by the square root of time. High-IV stocks produce a wide, rapidly expanding cone. Low-IV stocks produce a narrow, slowly expanding cone.

Most options platforms display the cone with at least two bands:

Inner band (1 SD): The 68% probability range. Selling options just outside this band places approximately a 68% theoretical probability that the option expires worthless.
Outer band (2 SD): The 95% probability range. Selling options just outside this band places approximately a 95% theoretical probability that the option expires worthless, but at the cost of much lower premium and a very poor risk/reward ratio on the occasional loss.

The cone boundaries are not hard limits. The stock can move outside the cone, and when it does, it is simply a realization that falls in the 32% (for 1 SD) or 5% (for 2 SD) tail of the distribution. These events happen regularly and should be part of any risk plan.

The ATM Straddle as a Direct Expected Move Reading

A shortcut for reading the expected move without calculating from IV is to observe the at-the-money straddle price directly. The combined premium of an ATM call and ATM put at the same strike and expiration approximates the market's consensus expected move by expiration.

The commonly cited approximation: expected move equals approximately 85% of the ATM straddle price. So if the ATM straddle costs $8.00, the implied expected move is roughly $6.80.

This relationship exists because the straddle's breakeven points (strike plus or minus total straddle cost) align closely with the one-standard-deviation boundaries. Market makers price ATM straddles to reflect the anticipated magnitude of stock movement, making the straddle price a direct market signal rather than a derived calculation.

Comparing a stock's historical average move around earnings to the expected move implied by the earnings-week straddle price is a common technique for assessing whether options are overpriced (IV too high for the historical move) or underpriced (IV too low) heading into the event.

How Events Inflate the Expected Move Cone

Implied volatility rises before catalysts that create outcome uncertainty: earnings announcements, FDA decisions for biotech stocks, Federal Reserve interest rate decisions, and major macroeconomic data releases. This IV expansion directly widens the expected move cone.

For a stock with a typical 30-day IV of 25%, a single earnings announcement in the near-term expiration may inflate the IV for that specific expiration to 60% or higher, more than doubling the expected move width for that date. The expirations after earnings quickly return to near-normal IV, creating a visible "kink" in the term structure of implied volatility.

After the event resolves, IV typically collapses sharply (IV crush), and the expected move cone for subsequent expirations narrows. Traders who bought options expecting a wide move must overcome this IV collapse in addition to needing the stock to move in their favor.

FAQ

What is the expected move in options trading?

The expected move is the implied price range that the options market prices for a stock by a specific expiration date. It represents approximately one standard deviation of expected price movement, derived from the implied volatility of at-the-money options. The one-standard-deviation expected move covers roughly a 68% probability range based on a lognormal distribution assumption, meaning the market implies approximately a 68% probability that the stock will finish within this range by expiration.

How is the expected move calculated from implied volatility?

The one-standard-deviation expected move can be estimated using this formula: Expected Move equals the stock price multiplied by the implied volatility multiplied by the square root of (days to expiration divided by 365). For example, a $100 stock with 20% implied volatility and 30 DTE would have an expected move of approximately $100 multiplied by 0.20 multiplied by the square root of (30/365), which equals approximately $5.75. This means the market implies roughly a 68% chance the stock stays within plus or minus $5.75 of its current price by that expiration.

What does the expected move cone look like on a chart?

The expected move cone is drawn as two diverging lines from the current price, one above and one below, that widen as time extends further into the future. The inner cone (one standard deviation) covers the 68% probability range. An outer cone (two standard deviations) covers approximately the 95% probability range. When plotted on a price chart, the cone resembles a funnel or horn shape, with the narrow end at the present and the wide end at the expiration date.

How can traders use the expected move cone for strike selection?

Premium sellers commonly use the expected move cone to identify strikes with a favorable probability of expiring out of the money. Selling options outside the one-standard-deviation cone means the stock must move beyond the implied expected range for the short option to be tested. Selling outside the two-standard-deviation cone offers even higher probability of profit but at the cost of collecting less premium. The cone provides a probabilistic framework, not a guarantee, and the market-implied probabilities assume the underlying follows a lognormal distribution.

How does the expected move relate to the ATM straddle price?

The price of the at-the-money straddle (the combined cost of an ATM call and ATM put with the same strike and expiration) is a direct market-priced estimate of the expected move. A common approximation is that the expected move equals approximately 85% of the ATM straddle price. So if the ATM straddle costs $6.00, the market is implying an expected move of roughly $5.10 in either direction by expiration. This relationship gives traders a quick way to read the implied expected move directly from straddle prices without calculating from IV.

Why does the expected move cone expand before earnings?

Implied volatility rises before earnings announcements because the outcome is uncertain and the potential stock move is large. As IV increases, the expected move formula produces a larger dollar range, so the cone widens. This higher IV can double or triple the expected move for the specific expiration covering earnings. After the announcement, IV collapses (IV crush), and the cone narrows significantly. This widening before and narrowing after creates the classic IV spike-and-drop pattern around earnings.

What are the limitations of the expected move cone?

The expected move cone assumes a lognormal distribution of returns, which historically underestimates the frequency of large moves (fat tails). Stocks occasionally move several standard deviations in a single session, especially around unexpected news. The cone is a probabilistic framework derived from market pricing of options, not a prediction of actual movement. It reflects what the market is pricing, which can itself be wrong if IV is mispriced. Traders should treat the cone as a probability guide, not a boundary the stock cannot cross.

References

Disclaimer

This article is for educational and informational purposes only. It does not constitute personalized investment, financial, or tax advice. Options trading involves significant risk, including the possible loss of the entire premium paid. All numerical examples are hypothetical and for illustration only. Consult a qualified financial professional before making trading decisions.

Expected Move Cone: Reading Options Implied Range