Earnings Straddle Expected Move: What the Premium Does and Does Not Say
For educational purposes only; not investment advice.
Direct answer
Section titled “Direct answer”An earnings straddle expected move uses the combined premium of a near-the-money Call and Put with the same strike and expiration as a quick estimate of the magnitude priced around an earnings release. If the stock is near $100 and the relevant ATM straddle costs $8, the premium represents roughly 8% of spot.
That does not mean the market guarantees a $92 to $108 range, assigns a specific probability to it, or predicts direction. The straddle also prices time outside the earnings event, implied-volatility skew, interest, dividends, supply and demand, and execution spreads. It is a reference for comparing price with a thesis, not a boundary the stock must respect.
Quick estimate versus isolated event variance
Section titled “Quick estimate versus isolated event variance”The quick calculation is:
Approximate move in dollars = ATM Call premium + ATM Put premium
Approximate move in percent = straddle premium ÷ spot price.
Use an expiration that occurs after the announcement and confirm whether results are before open or after close. Use executable or clearly labeled midpoint prices and record the timestamp. If spot lies between strikes, compare nearby straddles or use a forward/Delta-based ATM measure rather than silently choosing the more favorable strike.
The quick estimate includes every remaining day until expiration. A more refined event calculation compares variance across expirations bracketing the announcement to remove ordinary non-event time. Cboe describes its earnings implied-move analytics as using differences in implied volatility across post-earnings expirations. The refined result still reflects model and market assumptions; it is not a promise.
For a long straddle held to expiration, breakevens are approximately strike + total premium and strike − total premium. Those are strategy breakevens, not probabilities. Before expiration, a sufficiently favorable change in implied volatility can change the straddle’s resale value even without reaching either expiration breakeven.
Same $8, different interpretations
Section titled “Same $8, different interpretations”A stock trades at $100. The first weekly expiration after earnings has a $100 Call quoted $3.80/$4.20 and a $100 Put quoted $3.60/$4.00. Midpoints total $7.80; buying both at the asks costs $8.20. The displayed market for the straddle is therefore roughly $7.40/$8.20, not one certain $8 value.
Using $8.20, a purchased straddle costs $820 per standard 100-share contract and has expiration breakevens near $91.80 and $108.20. If the stock opens at $108 after earnings, the move is large but still does not guarantee a profit: the options have time remaining, IV has repriced, and liquidation occurs at executable bids. If the package can be sold for $7.50, the loss is $70 despite an 8% stock move.
Now suppose the next expiration is four weeks later and its straddle costs $11. The difference between $8.20 and $11 is not simply $2.80 of extra event move; option variance scales with time and the two expirations have different Greeks and surfaces. Comparing annualized IV or extracting forward variance is more defensible than subtracting premiums.
Interpretation checklist
Section titled “Interpretation checklist”- Verify the announcement time and choose the first liquid expiration that contains the event.
- Record spot, forward considerations, selected strike, Call and Put Bid/Ask, timestamp, and whether the figure uses midpoint or executable cost.
- Distinguish straddle premium, expiration breakeven, a model-based standard deviation, and a probability interval.
- Compare the estimate with absolute historical earnings gaps, including tails and changes in business or market regime.
- Inspect adjacent-expiration IV to separate event premium from ordinary calendar time.
- Check skew: downside Put and upside Call prices may imply asymmetric demand even though the headline estimate is directionless.
- Stress a move smaller than, near, and larger than the estimate with IV crush and widened post-event spreads.
- Include commissions, slippage, time decay, dividends, rates, and the possibility that one leg has no useful bid.
- Do not infer edge from a large premium alone; compare the price with an explicit view and loss budget.
- Recompute when spot, quotes, or the announcement schedule changes.
Common misconceptions
Section titled “Common misconceptions”- “The stock should stay inside spot plus or minus the straddle.” Actual moves can be much smaller or larger.
- “The estimate is a 68% probability range.” That label requires a stated model and conversion, not just adding premiums.
- “An 8% move makes an
$8long straddle profitable.” Entry asks, exit bids, IV, time, and strike location matter. - “The straddle predicts up or down.” It mainly prices magnitude; skew and positioning require separate interpretation.
- “Subtracting two expiration premiums isolates earnings.” Variance, not premium, must be adjusted for time and surface differences.
- “The midpoint is tradable.” It is a mark between Bid and Ask, not an execution guarantee.