Butterfly Spread
A three-strike structure with alternating buys and sells for maximum gain at the middle strike.
Profit / Loss Diagram
Call Butterfly Spread at expiration
What is this strategy?
The Butterfly Spread is a three-strike strategy producing the characteristic tent shape in the P&L diagram. It is built by buying 1 in-the-money or at-the-money option, selling 2 options at the middle strike, and buying 1 out-of-the-money option of the same type. All options share the same expiration. It is a neutral strategy seeking maximum gain when price finishes exactly at the middle strike.
The appeal of the Butterfly Spread is that risk is completely defined and capped. The most you can lose is the net debit paid. The most you can gain is the spread width minus that debit. That makes it excellent for traders wanting limited risk with a limited but predictable payoff.
The Butterfly Spread suits sideways markets or situations where you expect price to stay near current levels. It works best entered at elevated implied volatility, since a richer premium on the two short options lowers the net debit. It is a positive-theta strategy that benefits from the passage of time. Many professional traders use butterflies as a recurring structure, especially on indices such as SPY.
Construction
| Action | Instrument | Strike | Expiration | Example |
|---|---|---|---|---|
| BUY | 1 Call | ITM or ATM | 30-45 DTE | +1 SPY Aug 425 Call |
| SELL | 2 Calls | ATM (middle strike) | 30-45 DTE | -2 SPY Aug 430 Call |
| BUY | 1 Call | OTM | 30-45 DTE | +1 SPY Aug 435 Call |
Example
Scenario: SPY trades at $430. You expect it to stay near that level over the next 30 days.
- Call Purchased (425) +1 SPY Aug 425 Call @ $6.50
- Calls Sold (430) -2 SPY Aug 430 Call @ $4.00 each
- Call Purchased (435) +1 SPY Aug 435 Call @ $2.25
- Net Debit $75 (650 + 225 − 800)
- Maximum Gain $425 (5-point width × 100 − $75 debit)
- Maximum Loss $75 (debit paid)
- Breakevens $425.75 and $434.25 (outer strikes ± debit)
- Profit if SPY = $430 $425 (maximum gain)
The Greeks
Delta is near zero at the middle strike, where you expect price to sit. Balanced exposure in both directions.
Theta is your ally in butterflies. You gain daily, especially in the final week if you are near the centre.
Falling volatility benefits the position. You want low or contracting implied volatility.
Gamma is negative at the middle strike, meaning moves in either direction hurt you.
Position Management
- 01 Close at 75% of Maximum Gain Do not wait for expiration. If the position reaches $318 of the $425 maximum, close and redeploy. Avoid unnecessary adjustments.
- 02 Monitor Price Versus Strikes If price drifts far from the middle strike, your gain shrinks. Consider closing once you are down 25–30% of the debit.
- 03 Exploit the Final Days In the last 3–7 days before expiration, theta accelerates dramatically. If you are near the centre, the position gains quickly.
- 04 Adjust if Price Moves Away If SPY drifts well away from $430 — say to $420 or $440 — consider closing and opening a new butterfly at a more reachable range.
- 05 Consider a Wider Butterfly Instead of $5 spreads, some traders use $10 spreads for a larger maximum gain, at the cost of a narrower profit zone. Match the width to the expected range.