What Is the Expected Move?
The expected move is the range within which the market expects a stock to trade over a given period, derived from implied volatility. It represents one standard deviation of expected price change, meaning there is approximately a 68% probability the stock stays within this range. The expected move is critical for options traders because it sets the breakeven for straddle buyers and the profit zone for straddle sellers.
There are two ways to calculate the expected move: from implied volatility (mathematical approach) or from the ATM straddle price (market approach). Both give similar results, but the straddle method is more practical because it directly reflects market pricing. The expected move is especially important before earnings, FDA decisions, and other catalysts where large price moves are anticipated.
One standard deviation (1 SD) captures about 68% of outcomes. Two standard deviations (2 SD) capture about 95%. Three standard deviations (3 SD) capture about 99.7%. The expected move is one standard deviation, meaning the stock will trade outside this range about 32% of the time.
Expected Move Formulas
- 1From IV: $100 × 0.45 × sqrt(1/365) = $100 × 0.45 × 0.05234 = $2.36 (daily)
- 2But this is for 1 trading day with 45% IV
- 3From straddle: $7.00 × 0.85 = $5.95
- 4The straddle method is more accurate for earnings because it captures event premium
- 5Expected range: $94.05 to $105.95 (68% confidence)
- 6Stock needs to move more than $5.95 (5.95%) for straddle buyers to profit
- 7Two SD range: $88.10 to $111.90 (95% confidence)
| Time Period | Days | Expected Move ($) | Expected Move (%) | Range |
|---|---|---|---|---|
| 1 Day | 1 | $1.89 | 1.89% | $98.11 - $101.89 |
| 1 Week | 7 | $5.01 | 5.01% | $94.99 - $105.01 |
| 1 Month | 30 | $10.37 | 10.37% | $89.63 - $110.37 |
| 3 Months | 90 | $17.96 | 17.96% | $82.04 - $117.96 |
| 6 Months | 180 | $25.40 | 25.40% | $74.60 - $125.40 |
| 1 Year | 365 | $30.00 | 30.00% | $70.00 - $130.00 |
Using Expected Move in Trading
- The expected move is a probability estimate, not a guarantee
- Stocks move beyond the expected move about 32% of the time (1 SD)
- Before earnings, the straddle method is more accurate than the IV method
- The expected move increases with time (but not linearly; it follows sqrt of time)
- Higher IV stocks have larger expected moves for the same time period
Calculate the ratio of actual historical earnings moves to the implied expected move. If a stock consistently moves 1.3x the expected move, options are underpricing the event. If it moves only 0.7x, options are overpricing it. Use this ratio to decide whether to buy or sell options before earnings.
The expected move assumes a normal distribution of returns, which underestimates extreme events (fat tails). In reality, stocks experience gap moves, flash crashes, and momentum events that exceed 3 or more standard deviations. Risk management should account for moves beyond the expected range.
Understanding Risk Management in Options Trading
Effective risk management is the foundation of long-term options trading success. Unlike stock investing where your maximum loss is your initial investment, options strategies can have complex risk profiles that require careful monitoring. Defined-risk strategies (spreads, iron condors, covered calls) have a known maximum loss before entering the trade, making position sizing straightforward. Undefined-risk strategies (short naked options) require understanding margin requirements and the potential for losses exceeding initial premium collected. All options traders should use the probability of profit (POP) metric — available on most options platforms — to understand the statistical edge before entering any trade.
Managing winning trades is as important as cutting losers. Research from tastytrade and other quantitative options firms shows that closing profitable short options positions at 50% of maximum profit significantly improves risk-adjusted returns compared to holding to expiration. The intuition: after capturing 50% of the premium, the remaining time risk (gamma risk near expiration) exceeds the potential reward. By closing early, you free up capital for new trades and eliminate the tail risk of a sudden reversal wiping out unrealized profits. This 'take profits at 50%' rule is one of the most robust findings in systematic options trading research.
