Butterfly Spread¶
OVERVIEW¶
A butterfly spread is a neutral options strategy built from four contracts across three equidistant strikes, designed to profit when the underlying closes at or near the middle strike on expiration day. Both risk and reward are strictly capped.
Note
Butterflies are the cheapest way to express a specific price-target view. The trader is paid to be precisely right about where the stock will trade on a specific date.
The payoff diagram resembles a tent or the wings of a butterfly. Common use cases include earnings pins, FOMC day pins, and index max-pain expirations.
CONSTRUCTION¶
The standard long call butterfly uses four contracts at three strikes where K1 < K2 < K3 and the strikes are equidistant (K2 − K1 = K3 − K2):
| Leg | Position | Strike | Moneyness |
|---|---|---|---|
| 1 | Long 1 call | K1 | In-the-money |
| 2 | Short 2 calls | K2 | At-the-money |
| 3 | Long 1 call | K3 | Out-of-the-money |
All contracts share the same expiration date.
Tip
The same P&L profile can be built with puts (long put butterfly). An iron butterfly substitutes puts on the downside leg and calls on the upside leg, creating a short straddle + long strangle combination that opens for a net credit rather than a debit.
Key Formulas¶
| Value | Formula |
|---|---|
| Net debit | Premium(K1) − 2 × Premium(K2) + Premium(K3) |
| Max profit | (K2 − K1) − Net debit, at expiration with underlying at K2 |
| Max loss | Net debit, if underlying closes ≤ K1 or ≥ K3 |
| Lower breakeven | K1 + Net debit |
| Upper breakeven | K3 − Net debit |
WORKED EXAMPLE¶
Setup: SPY trades at $500.00 on 2026-04-21. A trader expects SPY to pin near $500 into the 2026-05-16 monthly expiration and opens a 490/500/510 call butterfly.
| Leg | Contract | Premium |
|---|---|---|
| Long 1 call | May 16 $490 call | $12.00 debit |
| Short 2 calls | May 16 $500 calls | $5.00 credit each = $10.00 credit |
| Long 1 call | May 16 $510 call | $1.00 debit |
Results:
| Metric | Value |
|---|---|
| Net debit | $12.00 − $10.00 + $1.00 = $3.00/share ($300/spread) |
| Max profit (SPY = $500 at expiry) | $10 wing width − $3 debit = $7.00 × 100 = $700 |
| Max loss | $300 (SPY finishes below $490 or above $510) |
| Lower breakeven | $493 |
| Upper breakeven | $507 |
| Return on risk | $700 / $300 = 233% |
Note
The trader risks $300 to make up to $700 over 25 days. The full payoff window is only $14 wide. Max profit requires SPY to close within that range at expiration.
WHEN TO USE¶
| Use Case | Structure | Rationale |
|---|---|---|
| Earnings pin | Long call or put butterfly | Profit if stock closes near a specific target without paying full straddle premium |
| FOMC / event pin | Long butterfly | High-conviction directional pinning at low cost |
| Short volatility income | Iron butterfly | Defined-risk alternative to an undefined-risk short straddle |
| Downside tail hedge | Broken-wing butterfly | Skew payoff toward downside protection without upfront put premium |
LIMITATIONS¶
Note
Max profit is only achieved at expiration and only at the exact middle strike. Closing early rarely captures more than 60–70% of theoretical max because extrinsic value remains on the short strikes until the final session.
| Limitation | Detail |
|---|---|
| Strike sensitivity | Missing the center strike by one increment dramatically reduces the payoff |
| Implied volatility drag | Buying into elevated IV (e.g., pre-earnings) increases debit and cuts max return |
| Commission cost | Four legs per butterfly, eight on an iron fly — contract drag is material on small accounts |
| Timing | Full payoff requires holding to expiration at the precise center strike |