The iron butterfly sells a call option and a put option at the same middle strike, and buys protection on both sides. It collects a large credit for a range-bound view, with a defined maximum loss.
Its reward-to-risk ratio looks unusually attractive on paper. This article works through an example, explains why that ratio comes with a lower probability of success than it suggests, and compares it with the iron condor and the long butterfly.
How it is built
An iron butterfly has four legs, all in the same expiry:
Sell one call option at the middle strike, usually at or near the current price.
Sell one put option at the same middle strike.
Buy one call option at a higher strike.
Buy one put option at a lower strike, usually the same distance below.
The two sold options form a short straddle, which collects a large premium but carries open-ended risk. The two bought options are the wings, capping the loss on each side.
The structure profits most if the underlying finishes exactly at the middle strike at expiry, and its profit falls away on either side. It is closely related to the iron condor, which sells options at two different strikes rather than one, and to the long butterfly, which produces the same shape using options of a single type with a net debit.
A worked example
Suppose an index is at 24,000. Illustrative prices for options two weeks from expiry, consistent with the other strategy examples on this site:
Sell the 24,000 call option at 170 and the 24,000 put option at 160, receiving 330.
Buy the 24,300 call option at 60 and the 23,700 put option at 55, paying 115.
Net credit: 330 − 115 = 215 per unit. Multiply by the lot size for rupees.
At expiry, at exactly 24,000: every option expires worthless or at zero intrinsic value. Profit: 215, the maximum.
At expiry, at or beyond the wings (above 24,300 or below 23,700): the spread on that side is worth its full width of 300. Loss: 300 − 215 = 85, the maximum.
Breakevens: 24,000 + 215 = 24,215 and 24,000 − 215 = 23,785.
So the trade risks 85 to make up to 215 — a ratio that looks far better than most credit structures.
Why the ratio is not free
The attractive ratio has a cost: the profitable range is narrow, and the maximum profit sits at a single point.
The profit zone is the range between the breakevens, here about 215 points on either side of the middle strike. Any finish outside that range loses money.
The maximum profit requires a finish exactly at the middle strike, which rarely happens. Most profitable outcomes earn a fraction of 215.
Losses start quickly. A move of just over 215 points either way by expiry turns the trade into a loss, and a move to the wings produces the full loss.
Over a two-week period, moves of that size are common. Depending on volatility, the chance of finishing outside the breakevens can be close to, or even more than, the chance of finishing inside. The high ratio and the lower probability are two sides of the same calculation.
Compared with an iron condor, which sells options further from the price, the iron butterfly collects more premium and has a better ratio, but a narrower range in which it profits.
Behaviour before expiry
Time works for it. The sold options at the middle strike carry the most time value and lose it fastest, so the position gains as days pass if the index stays near the middle.
Movement works against it. As the index moves away from the middle strike, the position loses value, and this sensitivity increases near expiry.
Volatility works against it. A rise in implied volatility raises the value of the sold options more than the bought wings, hurting the position before expiry.
Most of the profit arrives late. As with other short-volatility structures, a large share of the potential profit is realised only in the final days, when sensitivity to moves is highest.
Managing an iron butterfly
Take profits early. Many traders close once a meaningful share of the credit has been earned, rather than holding into the final days for the remainder.
Set a loss exit in advance, such as closing if the index moves beyond a set distance from the middle strike, or if the position's value rises to a set level.
Avoid events. Results, policy announcements or budgets during the life of the trade can produce exactly the large move the structure cannot handle.
Enter all four legs together using a basket order, to avoid holding the unprotected short straddle even briefly.
Count the costs. Four legs, each with charges and spreads on entry and exit.
Size by the maximum loss, not by the credit. The 85 points of risk per unit, multiplied by the lot size, is the number that matters for sizing.
An account with basket orders and payoff views
Place all legs together and see the defined risk before trading. Free to open
Prices in the example are illustrative, not market data. Lot sizes, margin rules and charges are set by the exchanges and SEBI and change from time to time. This is educational material, not advice, and no position is recommended. We run no tips group and no signal service, we manage nobody's money, and no return is promised. Derivatives can lose more than the amount blocked against them.
Disclosure: the account-opening link on this page is under Atul Shrivastava's Zerodha Authorised Person registration (NSE AP Reg: AP2516003481; Zerodha Broking Ltd. SEBI Reg: INZ000031633) and earns a revenue share. TheFinBaba is not a SEBI-registered Investment Adviser — this content is educational, not investment advice.
When the index drifts to one side, some traders try to repair the position by moving strikes or adding legs. Each adjustment adds costs and can turn a simple, defined-risk structure into something harder to reason about. Often the cleaner choice is to close the whole position at a predefined loss and reassess, rather than reshaping it repeatedly in the hope of recovering.
Frequently Asked Questions
What is an iron butterfly?
A four-leg options structure that sells a call option and a put option at the same middle strike and buys a call option above and a put option below as protection, collecting a net credit with a defined maximum loss.
How do I calculate the breakevens of an iron butterfly?
Add the net credit to the middle strike for the upper breakeven and subtract it for the lower breakeven.
What is the maximum loss on an iron butterfly?
The width between the middle strike and a wing, minus the net credit received, multiplied by the lot size.
How is an iron butterfly different from an iron condor?
An iron butterfly sells both options at one middle strike, collecting more premium with a narrower profit range. An iron condor sells them at two strikes, with a wider range and a smaller credit.
Why does the iron butterfly have a good reward-to-risk ratio?
Because it collects a large credit relative to its maximum loss. The trade-off is a narrow profit range and a lower chance of success.
Related Reading
- Call options from first principles
- Put options from first principles
- The wider-range iron condor
- The long butterfly with a debit
- The short straddle at its core
- Taking profits before the final days
Disclaimer: TheFinBaba provides educational content only - this is not investment advice. Trading involves risk of loss.
