To calculate the implied move for earnings, add together the at-the-money call and put premiums for the expiration just after the earnings release, then multiply the sum by 0.85. The result is the dollar amount the market expects the stock to move in either direction. For a stock trading near $150 with a $5.20 call and a $4.80 put at the $150 strike, the straddle costs $10.00, and the implied move works out to about $8.50, or roughly 5.67% up or down.
The Three Inputs You Need
Everything comes from the options chain on any brokerage platform.
- The current stock price. This anchors the calculation.
- The at-the-money strike, meaning the strike closest to the current stock price. If the stock trades at $150.25, use the $150 strike.
- The call and put premiums at that strike. Use the mid-price, the midpoint between the bid and ask, for each. Mid-price is more reliable than the ask alone, because the ask includes the market maker’s markup.
Expiration matters too. Pick the weekly cycle that expires soonest after earnings. Monthly options that expire weeks later bake in extra time value that distorts the reading.
When to Pull the Quotes
Timing changes the accuracy of this estimate. Data gathered the day before earnings or very close to expiration produces the tightest reading, because most of the time decay has already occurred and the remaining premium reflects almost purely the expected event-driven move. Pull the numbers a week ahead and you are measuring a mix of event risk and ordinary time value that muddies the result.
Running the Math
Two steps. First, add the call and put premiums to get the raw straddle cost. A $5.20 call and a $4.80 put give you a $10.00 straddle.
Second, multiply that straddle cost by 0.85. Ten dollars times 0.85 is $8.50. That is your implied move in dollar terms.
The 0.85 factor exists because the raw straddle price tends to overstate the actual move. Options premiums include compensation for time decay and for the seller’s risk, which inflates the number beyond what stocks typically deliver. Multiplying by 0.85 strips out some of that excess. It is not a precise scientific constant; it is a widely used approximation among professional traders that captures roughly one standard deviation of expected movement, meaning the stock should land within that range about 70% of the time.
Turning the Move Into a Price Range
Add and subtract the dollar move from the strike price.
- Upper boundary: $150.00 + $8.50 = $158.50
- Lower boundary: $150.00 − $8.50 = $141.50
The market is pricing in a range of $141.50 to $158.50 through expiration. Land inside that window and earnings were roughly in line with expectations. Blow past either boundary and the report surprised the market.
To express the move as a percentage, divide the dollar move by the stock price: $8.50 ÷ $150.00 = 0.0567, or about 5.67%. The percentage is what makes the number portable across stocks. A $2 move on a $20 stock and an $8.50 move on a $150 stock both represent about the same level of expected volatility, even though the dollar figures look nothing alike.
Putting the Number in Context
The implied move alone does not tell you whether options are cheap or expensive. That context comes from comparing this quarter’s implied move to what the stock has actually done after prior earnings reports. If a stock has averaged a 3% move over the last eight quarters but options are pricing in 5.67% this time, the market is expecting an unusually large reaction. Either something genuinely different is happening, or the options are overpriced relative to history.
You can build the comparison yourself by tracking the stock’s actual next-day price change after each of the last several earnings dates and averaging the absolute values. Many brokerage platforms display this data alongside the options chain, sometimes labeled “earnings move history” or similar. When the implied move consistently runs above the historical average, straddle sellers tend to profit over time. When it runs below, buyers get a discount on volatility.
Why Being Right Isn’t Always Enough
This is where people new to options often get burned. Implied volatility spikes in the days before earnings because uncertainty is high and both calls and puts are in demand. The moment the report drops and the uncertainty resolves, implied volatility collapses. Traders call this IV crush, and it can wipe out the value of a straddle even when the stock moves in the predicted direction.
Say you bought that $10.00 straddle before earnings. The company reports strong numbers and the stock jumps 4% overnight. You would expect a profit. But the call might only be worth $7.00 the next morning, because the implied volatility component that propped up the premium has evaporated. The put is nearly worthless. Your straddle is now worth $7.00 against a $10.00 cost, a $3.00 loss despite being right about direction.
IV crush is the main reason the straddle method works as a forecasting tool but does not automatically translate into a profitable trade. The implied move tells you what the market expects. Profiting from that expectation requires the stock to move more than the implied range, not just within it.
What Can Throw the Estimate Off
The calculation is a useful estimate, not a precise forecast. A few conditions weaken it.
- Wide bid-ask spreads. Illiquid options can have a large gap between bid and ask. Using the mid-price helps, but if the spread is wide enough the midpoint may not reflect where you would actually get filled. Thinly traded names produce less reliable implied-move readings than high-volume stocks with tight spreads.
- Skew between the call and put. If the market leans directionally, worried more about a drop than a rally or the reverse, the call and put premiums at the same strike will not be balanced. The straddle still works, but the implied range is more likely to be breached on the side the market has loaded up on.
- Multiple events near expiration. If an economic report, a regulatory decision, and the earnings call all fall within the same expiration window, the straddle cost reflects all of them together. You cannot isolate the expected move from one catalyst when the premiums are pricing in several.
- After-hours gaps. Most earnings are released before the open or after the close. The stock can gap dramatically at the open, but the options do not trade until then. The implied move estimates the total swing; the path from close to open can involve more slippage than intraday trading.
None of these makes the method unreliable. They mean the output is a well-informed estimate, not a guarantee.