Iron Butterfly
Short straddle + long strangle
What is Iron Butterfly?
Iron Butterfly An iron butterfly (also called an "iron fly") is a four-leg neutral options strategy combining a short ATM straddle with long OTM wings for protection. Structure: sell 1 ATM call, sell 1 ATM put (the same strike), buy 1 OTM call above, buy 1 OTM put below. The result is a defined-risk premium-selling structure with a tighter profit zone but higher reward-to-risk than the iron condor. Mechanics: - Sell 1 ATM put (the body — same strike as the short call) - Sell 1 ATM call (the body — same strike as the short put) - Buy 1 lower OTM put (wing — protects against crash) - Buy 1 higher OTM call (wing — protects against rally) Iron butterflies are the close cousin of iron condors. The key difference: iron condors sell different short put and short call strikes (creating a wide profit zone), while iron butterflies sell the same short put and call strikes (creating a tight, spike-shaped profit zone). Worked example, SPY at $540: - Sell 540P at $4.20, sell 540C at $4.10 (combined: $8.30 credit on the short straddle body) - Buy 530P at $1.40, buy 550C at $1.00 (combined: $2.40 debit on the wings) - Net credit: $5.90 ($590 per contract) - Max profit: $590, realized only if SPY closes exactly at $540 at expiration - Max loss: $10 (wing width) − $5.90 (credit) = $4.10 ($410) - Reward-to-risk: $590 / $410 = 1.44× — meaningfully better than a typical iron condor The trade-off: iron butterflies have higher reward-to-risk but materially lower probability of profit. The profit zone is the spike at the body strike; iron condors have a flat-top profit zone roughly 4-6% wide. Iron butterfly vs iron condor: | Metric | Iron Condor | Iron Butterfly | |--------|------------|----------------| | Profit zone | Wide (4-6% of spot) | Narrow (pin to strike) | | Max profit | Lower (credit) | Higher (credit) | | Reward-to-risk | 0.3-0.4× | 1.3-1.6× | | Win rate | 65-70% | 30-40% | | Best for | Range-bound | Pin to specific price | | IV regime | Moderate | High (pre-event), then crush | When iron butterflies work: - **Pre-earnings or pre-event premium selling**: high IV makes the body short straddle rich; post-event IV crush amplifies profits even if pin doesn't perfectly hold. - **High-conviction pin theses**: stocks anchored to round-number strikes by heavy dealer gamma exposure tend to pin to those strikes into expiration. - **Capital-constrained traders**: the higher reward-to-risk per dollar of risk means you can size smaller and still earn meaningful absolute dollars on winners. Common mistakes: - **Going wing-too-wide**: increases max loss without proportionally increasing max profit. $10-wide wings are typical; $20-wide wings rarely improve outcomes. - **Holding to expiration**: gamma risk in the final week converts winning butterflies into losers on small adverse moves. Close at 50-75% of max profit. - **Treating it as a high-probability strategy**: 30-40% win rate is structural. Size accordingly; one winner needs to cover several losers.
Complete Definition
An iron butterfly (also called an "iron fly") is a four-leg neutral options strategy combining a short ATM straddle with long OTM wings for protection. Structure: sell 1 ATM call, sell 1 ATM put (the same strike), buy 1 OTM call above, buy 1 OTM put below. The result is a defined-risk premium-selling structure with a tighter profit zone but higher reward-to-risk than the iron condor. Mechanics: - Sell 1 ATM put (the body — same strike as the short call) - Sell 1 ATM call (the body — same strike as the short put) - Buy 1 lower OTM put (wing — protects against crash) - Buy 1 higher OTM call (wing — protects against rally) Iron butterflies are the close cousin of iron condors. The key difference: iron condors sell different short put and short call strikes (creating a wide profit zone), while iron butterflies sell the same short put and call strikes (creating a tight, spike-shaped profit zone). Worked example, SPY at $540: - Sell 540P at $4.20, sell 540C at $4.10 (combined: $8.30 credit on the short straddle body) - Buy 530P at $1.40, buy 550C at $1.00 (combined: $2.40 debit on the wings) - Net credit: $5.90 ($590 per contract) - Max profit: $590, realized only if SPY closes exactly at $540 at expiration - Max loss: $10 (wing width) − $5.90 (credit) = $4.10 ($410) - Reward-to-risk: $590 / $410 = 1.44× — meaningfully better than a typical iron condor The trade-off: iron butterflies have higher reward-to-risk but materially lower probability of profit. The profit zone is the spike at the body strike; iron condors have a flat-top profit zone roughly 4-6% wide. Iron butterfly vs iron condor: | Metric | Iron Condor | Iron Butterfly | |--------|------------|----------------| | Profit zone | Wide (4-6% of spot) | Narrow (pin to strike) | | Max profit | Lower (credit) | Higher (credit) | | Reward-to-risk | 0.3-0.4× | 1.3-1.6× | | Win rate | 65-70% | 30-40% | | Best for | Range-bound | Pin to specific price | | IV regime | Moderate | High (pre-event), then crush | When iron butterflies work: - **Pre-earnings or pre-event premium selling**: high IV makes the body short straddle rich; post-event IV crush amplifies profits even if pin doesn't perfectly hold. - **High-conviction pin theses**: stocks anchored to round-number strikes by heavy dealer gamma exposure tend to pin to those strikes into expiration. - **Capital-constrained traders**: the higher reward-to-risk per dollar of risk means you can size smaller and still earn meaningful absolute dollars on winners. Common mistakes: - **Going wing-too-wide**: increases max loss without proportionally increasing max profit. $10-wide wings are typical; $20-wide wings rarely improve outcomes. - **Holding to expiration**: gamma risk in the final week converts winning butterflies into losers on small adverse moves. Close at 50-75% of max profit. - **Treating it as a high-probability strategy**: 30-40% win rate is structural. Size accordingly; one winner needs to cover several losers.
Example
SPX at 5,800 the day before FOMC. IV is elevated. Sell SPX 5,800 iron fly with 50-wide wings: net credit $32 ($3,200 per contract). FOMC announcement is non-event; SPX closes at 5,803 the next day. Position closes for $14 debit — net $1,800 profit. Same trade with iron condor (5,775P/5,825C body) would have been a smaller credit but with a wider profit zone.
Related Terms
Frequently Asked Questions
What is an iron butterfly?
An iron butterfly is a four-leg neutral options strategy combining a short ATM straddle with OTM long wings for protection. Sell 1 ATM call, sell 1 ATM put, buy 1 OTM call (upper wing), buy 1 OTM put (lower wing). The structure has high reward-to-risk but a narrow profit zone — only profits if the underlying pins near the strike.
How is an iron butterfly different from an iron condor?
An iron butterfly sells the same strike for both short legs (tight profit zone, high reward-to-risk). An iron condor sells different strikes for short put and short call (wide profit zone, lower reward-to-risk). Butterflies suit pin theses; condors suit range-bound expectations.
When should I trade an iron butterfly?
When you have a high-conviction pin thesis (post-vol-spike, near a strike with heavy dealer gamma, around binary events with expected IV crush). The strategy is best for capital-efficient income generation with a willingness to take small losses on lower probability.
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