Iron butterfly strategy explained: sell an at-the-money straddle, buy wings, collect a big credit. SPY example vs iron condor, Greeks and exit rules.
Summary: An iron butterfly sells an at-the-money put and an at-the-money call at the same strike and buys a cheaper put below and a cheaper call above as wings. It collects a much larger credit than an iron condor, but the maximum gain only arrives if the stock finishes exactly at the middle strike, and the profit zone is narrow. Both the maximum gain and the maximum loss are known on day one. It suits a stock you expect to stay pinned near its current price, with elevated implied volatility and a plan to take gains early.
Last updated: 2026-10-17.
What Is an Iron Butterfly?
An iron butterfly is a four-leg options position built around one strike. You sell a put and a call at the same at-the-money strike, then buy a put further below and a call further above, all with the same expiration. The two short options form a short straddle; the two long options are wings that cap the loss on each side.
It's a close relative of the iron condor. Both are credit strategies that want the stock to stay put. The difference is where the short strikes sit. An iron condor sells options out of the money and leaves a wide zone between them. An iron butterfly sells both options right at the current price, so the zone collapses to a single point — and the credit grows several times larger.
That trade-off is the whole strategy. You collect more, but the stock has to stay much closer to the middle for you to keep it. The payoff diagram shows why it's called a butterfly: a sharp peak in the center and two flat wings hanging down on either side.
The Archery Target Analogy
Same risk, different target: the iron butterfly pays most only near the middle strike.
Picture two archery targets. On the first, every arrow that hits anywhere on the board scores the same modest number of points. That's the iron condor: a wide area, a small reward, and you hit it most of the time. On the second, only the bullseye pays the full score, the rings around it pay less and less, and the outer edge pays nothing. That's the iron butterfly: the closer the stock finishes to the middle strike, the more you keep.
The analogy has one honest catch. An archer aims; a trader doesn't. You can't steer the stock toward the bullseye — you can only choose a target where it seems likely to land. With the iron butterfly in this example, the model gives about a one-in-three chance of finishing anywhere in the scoring rings.
Key Facts
- An iron butterfly sells an at-the-money put and call at one strike and buys a lower put and a higher call; the net credit is the maximum gain.
- Maximum loss = (wing width − credit) × 100: in this example ($30 − $22.64) × 100 = $736.
- Break-evens = middle strike ± credit: $737.36 and $782.64 here, only about 3% either side of $760.
- In the SPY example, the iron butterfly risks $736 to gain up to $2,264 — nearly the same risk as this example's comparison iron condor ($747), with about nine times the maximum gain.
- The price of that reward: a model probability of about 36% of finishing between the break-evens, versus about 72% for the iron condor.
- Theta works for you, but late: with SPY unchanged, the position shows only about $292 with 21 days left and reaches 25% of its maximum gain with about 11 days left.
- Vega is larger than an iron condor's: each 1-point rise in implied volatility costs about $37.
How an Iron Butterfly Is Constructed
The setup has four legs, normally opened as one order:
- Buy one put below the price — the lower wing.
- Sell one put at the money — the center.
- Sell one call at the same at-the-money strike — also the center.
- Buy one call above the price, the same distance away — the upper wing.
Seen another way, legs 1–2 are a bull put spread and legs 3–4 are a bear call spread, just like an iron condor — except both spreads share the same short strike. The formulas:
Net credit = (short put + short call) − (long put + long call)Max gain = net credit × 100 (stock exactly at the middle strike at expiration)Max loss = (wing width − net credit) × 100 (stock beyond either wing)Lower break-even = middle strike − net creditUpper break-even = middle strike + net credit
As with an iron condor, the stock can finish beyond only one wing, so the risk is one wing's width, not two. See margin and buying power for options for how brokers handle multi-leg positions.
Iron Butterfly Example: SPY
The SPDR S&P 500 ETF (SPY) closed at about $763 on October 16, 2026, according to the SPY quote on StockAnalysis. The example uses the same illustrative scenario as the iron condor used for comparison later in this article — SPY at $760, 45 days to expiration, implied volatility of 18%, a 4% interest rate, and a dividend yield of about 1% — so the two strategies can be compared directly. The numbers are for learning the mechanics, not a recommendation to trade SPY.
The same event risk applies: a 45-day position opened now spans the Federal Reserve meeting on October 27–28, 2026 and the U.S. midterm elections on November 3. This example knowingly holds through both. Because an iron butterfly's profit zone is narrow, a single big day matters even more here than for an iron condor.
Your view: SPY stays close to $760 for the next six weeks. You open this iron butterfly:
| Leg | Option | Delta | Price |
|---|
| Buy | 1 SPY $730 put | −0.23 | $6.75 |
| Sell | 1 SPY $760 put | −0.46 | $17.73 |
| Sell | 1 SPY $760 call | +0.54 | $20.53 |
| Buy | 1 SPY $790 call | +0.30 | $8.87 |
| Parameter | Value |
|---|
| Price (illustrative) | $760 |
| Days to expiration | 45 |
| Implied volatility (assumed) | 18% |
| Net credit (max gain) | $22.64 per share = $2,264 |
| Max loss | $7.36 per share = $736 |
| Break-evens at expiration | $737.36 and $782.64 (±2.98%) |
| Wing width | $30 |
| Reward-to-risk | 3.08 : 1 |
On paper, this looks better than almost any credit strategy: you risk $736 to gain up to $2,264. The catch is in the probabilities. The model gives SPY about a 36% chance of finishing between $737.36 and $782.64, and about a 53% chance of finishing beyond one of the wings, which means the full $736 loss at expiration. These are model estimates under the assumed volatility, not real-world frequencies — but they show why nobody holds an iron butterfly to expiration hoping for the bullseye.
The wing width is your main dial. Narrower wings cut the maximum loss but also the credit; wider wings collect more and turn the position into something close to a naked short straddle. The $30 wings here were chosen so the maximum loss roughly matches the $747 of the comparable iron condor, which makes the comparison below fair.
Iron Butterfly Payoff Diagram
At expiration, the payoff is a sharp tent. At exactly $760 you keep the full $2,264. Every $1 SPY finishes away from $760 costs $100, until the loss reaches $736 at $730 or $790 and stops there.
Iron butterfly payoff at expiration, with a comparable iron condor dashed for reference.
| SPY at expiration | Iron butterfly P/L | Iron condor P/L (same risk) |
|---|
| $700 | −$736 | −$747 |
| $730 | −$736 | +$253 |
| $745 | +$764 | +$253 |
| $760 (flat) | +$2,264 | +$253 |
| $775 | +$764 | +$253 |
| $790 | −$736 | +$253 |
| $820 | −$736 | −$247 |
Read the table from the middle outward. Near $760, the iron butterfly is far ahead. At a move of about $20 (2.6%), the iron condor catches up, and at $730 or $790 — a move of about 4% — the iron butterfly is at its maximum loss while the iron condor still keeps its full credit.
Iron Butterfly vs Iron Condor
Iron butterfly vs iron condor with about the same maximum loss.
| Iron butterfly ($730/$760/$790) | Iron condor ($705/$715/$815/$825) |
|---|
| Net credit (max gain) | $2,264 | $253 |
| Max loss | $736 | $747 |
| Break-evens | $737.36 / $782.64 | $712.47 / $817.53 |
| Model chance between break-evens | About 36% | About 72% |
| Theta per day at entry | About $7.26 | About $5.19 |
| Vega per IV point | About −$37 | About −$26 |
| Fits best when | You expect the price to stay pinned near one level | You expect a range |
Neither one is the "better" strategy. The iron condor gains a little most of the time and loses a lot occasionally. The iron butterfly reverses the pattern: it loses more often, but its gains, when they come, are several times larger. Choosing between them is choosing which kind of losing streak you can live with.
How the Greeks Affect an Iron Butterfly
The table shows the net values per share; the right-hand column translates them into dollars per iron butterfly. (Background in the option Greeks explained.)
| Greek | Net value (per share) | What it means for you |
|---|
| Delta (Δ) | −0.005 | About −$0.46 per $1 SPY moves — neutral at entry |
| Gamma (Γ) | −0.003 | Larger than the iron condor's: delta turns against you faster as SPY moves away from $760 |
| Theta (Θ) | +0.073 | Time decay earns about $7.26 per day at entry, all else equal |
| Vega (ν) | −0.374 | Each 1-point rise in implied volatility costs about $37 |
Theta arrives late. The short options are at the money, and at-the-money options lose most of their time value in the final weeks. If SPY sits at $760, the position shows a gain of about $86 after ten days, about $292 with 21 days left, about $483 with 14 days left, and about $845 with a week left. The bulk of the $2,264 is only collected in the last few days — exactly when gamma is highest.
Before expiration, the position is much more forgiving than the expiration diagram suggests. With 21 days left, SPY at $750 or $770 still shows a gain of about $250, and at $780 about $130, because the options still hold time value. The sharp tent only appears in the final days.
Vega is the other big risk. If implied volatility drops from 18% to 14% right after entry, the position shows about $186 of gain. If it rises to 22%, it shows a loss of about $125; at 26%, about $214 — before SPY has moved at all. For more on volatility, see implied volatility explained.
When to Use an Iron Butterfly
- You expect the price to stay pinned. Not just a range — a narrow one, close to the current price.
- Implied volatility is elevated. An IV rank above about 50% makes the at-the-money credit rich, and a later drop in IV helps you.
- No big event you aren't prepared to hold through. A single gap of 3–4% can take the position to its maximum loss.
- You're willing to manage actively. An iron butterfly isn't something you open and forget for six weeks.
When NOT to Use an Iron Butterfly
- Before earnings or major announcements. The expected move usually dwarfs the profit zone.
- When implied volatility is low. The credit shrinks and any rise in volatility works against you.
- When the stock is trending. Even a slow drift of 1% a week reaches a break-even within three weeks.
- When you want a high success rate. If frequent small gains matter more to you than the size of each gain, the iron condor fits better.
Iron Butterfly Entry Criteria and Exit Rules
Entry Criteria: When to Open an Iron Butterfly
- Neutral view with a specific price level you expect the stock to hold near.
- IV rank above about 50%.
- No major event you aren't prepared to hold through.
- 30–45 days to expiration.
- Short strikes at the money; choose the wing width by the maximum loss you accept (here the credit is about 75% of the width).
- Size by the maximum loss, not by the credit.
Exit Rules: Managing an Iron Butterfly
When to open an iron butterfly and how to manage it.
- Take gains at about 25% of the maximum. That's about $566 here. It's a lower target than the 50% common for iron condors, because the full credit only comes with the stock exactly at the middle strike. With SPY unchanged, it arrives with about 11 days left.
- Close if a break-even is touched. Once SPY trades at $737 or $783, early in the trade the position is near flat and the odds have turned against it.
- Use a time stop. Many traders close by 21 days to expiration, accepting a smaller gain (about $292 if SPY is unchanged) to avoid the gamma risk of the final weeks. Holding to 14 days raises that to about $483, but the position swings much harder by then.
- Don't hold through expiration. With both short options at one strike, one of them is almost always in the money at expiration, so you'd face assignment and an unwanted stock position after expiration.
- Close all four legs together. Leaving a short option without its wing removes the cap on the loss.
Re-centering a Tested Iron Butterfly
Say SPY drifts up to $775 with 30 days left. The position now has a delta of about −0.075 (about −$7.50 per $1 SPY rises) and shows a small gain of about $81. A common adjustment is to re-center: close the whole position for about $21.83 and open a new $745/$775/$805 iron butterfly with the same expiration for about $21.35. You keep the $81, the bullseye moves to $775, and the new maximum loss is $865. Re-centering is a new trade with new risk, not a repair — if SPY keeps drifting, you'll face the same decision again.
💡 Pro Tip: In a real brokerage account, an in-the-money short option can be assigned early, especially when it has almost no time value left. A short SPY call that's in the money can also be assigned the day before an ex-dividend date — though SPY's next one falls after this example's expiration. If that happens, close the remaining legs together with the shares to restore the defined risk. See what happens at options expiration for how assignment works.
Common Iron Butterfly Mistakes
- Judging it by the reward-to-risk ratio alone. 3 : 1 looks wonderful until you see the 36% probability next to it.
- Waiting for the maximum gain. The full $2,264 requires SPY to close at exactly $760 on the last day.
- Ignoring the event calendar. A profit zone of ±3% doesn't survive many large market days.
- Re-centering again and again. Each adjustment resets the risk and adds transaction costs; it's easy to turn one losing trade into several.
- Ignoring transaction costs. Four legs mean four commissions and four bid-ask spreads at a real broker, both to open and to close.
⚠️ Warning: In this example the iron butterfly ends at its maximum loss more often than it ends with any gain, under the model's assumptions. It works only with disciplined early exits and position sizes that survive a long run of losses.
How to Practice Iron Butterflies Without Real Money
Pilots practice precision landings in a flight simulator long before they try them on a short runway. An iron butterfly is the short runway of credit strategies: there's little room for error, and the exits have to be automatic.
In the simulator, you can build an iron butterfly straight from the option chain: buy the two wings first, then sell the put and the call at the at-the-money strike with the same expiration. Because each wing is already in place, the simulator treats each side as a credit spread and reserves the spread width instead of the full cash a lone short put would lock. The "Strategies" tab also has an Iron Butterfly template that shows the required capital, maximum profit and loss, break-evens, and Greeks before you trade. Open the same iron butterfly and iron condor on several charts in the Random scenario and compare how often each one reaches its target; then use the Bull Market scenario to practice re-centering when the price drifts. Each run is a synthetic chart that has never existed, so you're practicing decisions, not memorizing history.
FAQ
What is an iron butterfly?
An iron butterfly is an options strategy that sells an at-the-money put and call at the same strike and buys a lower-strike put and a higher-strike call as wings, all with one expiration. You receive a net credit, keep the most if the stock finishes exactly at the middle strike, and lose at most the wing width minus the credit.
What is the difference between an iron butterfly and an iron condor?
Both combine a bull put spread and a bear call spread. An iron condor sells out-of-the-money options with a wide gap between them; an iron butterfly sells both options at the same at-the-money strike. In the SPY example, the iron butterfly collects $2,264 against $736 of risk with about a 36% model chance of a gain at expiration, while the iron condor collects $253 against $747 with about 72%.
How do you calculate the break-evens of an iron butterfly?
Add the net credit to the middle strike for the upper break-even and subtract it for the lower one. In the example, $760 + $22.64 = $782.64 and $760 − $22.64 = $737.36.
When should you close an iron butterfly?
Common rules are to take gains at about 25% of the maximum, close if the stock reaches a break-even, and close by around 21 days to expiration. Don't hold through expiration, because one of the short options is almost always in the money at the end.
Related: Iron Condor Strategy, Bull Put Spread Strategy, Bear Call Spread Strategy, Implied Volatility Explained, Option Greeks Explained.
About the author: Miroslav Slavkovský is the founder of OptionsSimulator and a software developer focused on derivatives-pricing models. He built the platform's simulation engine — implementing Heston, SABR, GARCH, and Monte Carlo methods — so traders can practise options strategies on generated market scenarios rather than on historical charts.
Practice Iron Butterflies on a Synthetic Chart
Want to see whether you'd really take 25% and walk away — without risking real money? Open the simulator, build an iron butterfly from the option chain, and manage it with the rules above on a synthetic chart that has never existed.
Open Simulator
Frequently asked questions
What is an iron butterfly?
An iron butterfly is an options strategy that sells an at-the-money put and call at the same strike and buys a lower-strike put and a higher-strike call as wings, all with one expiration. You receive a net credit, keep the most if the stock finishes exactly at the middle strike, and lose at most the wing width minus the credit.
What is the difference between an iron butterfly and an iron condor?
Both combine a bull put spread and a bear call spread. An iron condor sells out-of-the-money options with a wide gap between them; an iron butterfly sells both options at the same at-the-money strike. In the SPY example, the iron butterfly collects $2,264 against $736 of risk with about a 36% model chance of a gain at expiration, while the iron condor collects $253 against $747 with about 72%.
How do you calculate the break-evens of an iron butterfly?
Add the net credit to the middle strike for the upper break-even and subtract it for the lower one. In the example, $760 + $22.64 = $782.64 and $760 − $22.64 = $737.36.
When should you close an iron butterfly?
Common rules are to take gains at about 25% of the maximum, close if the stock reaches a break-even, and close by around 21 days to expiration. Don't hold through expiration, because one of the short options is almost always in the money at the end.