Iron Butterfly

Quick answer: An Iron Butterfly is a defined-risk neutral strategy that sells an at-the-money put and call on one strike and buys wings above and below, collecting a large credit kept in full only if the underlying settles at the centre strike.

In simple words

An iron butterfly is a short straddle with training wheels. You sell a put and a call at the same central price, which brings in a large amount of premium because at-the-money options are expensive. Then you buy a cheaper put below and a cheaper call above to cap the risk on each side. The most favourable outcome is that the market finishes exactly on the strike you sold, where both of those options expire worthless and you keep the full credit. The further price drifts from that centre, the more of the credit you give back, until beyond the wings the loss is fixed at a known amount.

Payoff diagram

Professional explanation

Three strikes, not four

An iron butterfly collapses the two short strikes of an iron condor onto a single central strike. On the illustrative chain both the short put and the short call sit at 24,000, with wings bought at 23,600 and 24,400. Selling two at-the-money options collects far more premium than selling two out-of-the-money options, so the credit is 330 per unit against the condor's 89. That larger credit is the reward for accepting a much narrower profit zone: the position makes its full amount only at a single point, and gives some back everywhere else.

Why the credit exceeds the loss here

Each wing is 400 points from the centre, so the width of one spread is 400. The maximum loss is width minus credit: 400 − 330 = 70 per unit, or ₹5,250 on a lot. Because the credit collected (330) is larger than the maximum loss (70), the arithmetic is the mirror image of a wide condor — a big potential win against a small potential loss, but earned only in a narrow band. The break-even hit-rate is 70 ÷ (70 + 330), about 17.5%, so the position can be wrong far more often than right and still break even, provided the wins land near the centre.

The profit tent and its breakevens

Payoff forms a sharp tent peaking at the centre strike. Above 24,000 the short call eats into the credit; below it the short put does. The breakevens are the centre plus and minus the credit: 24,000 ± 330 = 23,670 and 24,330. That is a band only 660 points wide in which the position is profitable at expiry, narrower than the condor's, which is the price of the larger credit. The position needs the underlying not merely to stay in a range but to finish near a specific level.

A short straddle with a seatbelt

The core of an iron butterfly is a short straddle — sell the at-the-money put and call — which on its own has undefined risk. The two long wings convert that into a defined-risk position by capping each tail. The trade-off is that the wings cost premium, reducing the credit from what a naked straddle would collect, and they cap the loss at a level the trader chooses through the wing distance. Wider wings mean more credit but a larger maximum loss; narrower wings mean the reverse.

Construction

1. Sell one at-the-money put (here the 24,000 put) and one at-the-money call (the 24,000 call) to form the short straddle core.
2. Buy one out-of-the-money put wing (the 23,600 put) to cap the downside.
3. Buy one out-of-the-money call wing (the 24,400 call) to cap the upside.
4. Check that both wings are equidistant from the centre so the maximum loss is symmetric, and confirm the net credit received.

Market outlook

A trader may study an iron butterfly when the expectation is that the underlying will finish very close to a specific level and that at-the-money implied volatility is rich enough to make the large credit worth the narrow target. It is a pin bet: it wants price to gravitate to the centre strike, which sometimes happens around large open-interest strikes near monthly expiry. The condition that invalidates it is any decisive move away from the centre, since the profit zone is only a few hundred points wide. It is poorly suited to a market with an open directional catalyst, where price is unlikely to settle on a single level.

Risk profile

The iron butterfly is a defined-risk position: the two long wings cap the loss from the short straddle at the centre, so the maximum loss is structural and known before entry. That cap equals the wing width minus the credit — 400 − 330 = 70 per unit, or ₹5,250 on one NIFTY lot of 75. The loss is small relative to the credit, but it is reached across most of the settlement range, since the position only keeps its full credit at a single point. Before expiry, being short two at-the-money options gives the position sharp negative gamma, so the mark swings quickly with each move; on physically settled stock options early assignment on a short leg can unbalance the structure.

Reward profile

The maximum reward is the full net credit, 330 per unit or ₹24,750 on one NIFTY lot, earned only if the underlying settles exactly at the centre strike so that both short options expire worthless. Away from the centre the reward tapers along the tent, remaining positive out to the breakevens at 23,670 and 24,330. The reward is large relative to the capped loss but is concentrated at a point, so the realistic outcome is usually a partial retention of the credit rather than the full amount.

Margin requirement

Both short legs are hedged by wings, so the exchange grants spread benefit and the margin is roughly the net risk of the wider single spread rather than a naked straddle. Because the shorts are at the money, the position carries more gamma and its margin can rise faster during a move than a comparable condor's. SPAN plus exposure applies and NSE and brokers revise the formulas periodically.

Greeks exposure

The sign on each Greek above is computed, not asserted: it is the net exposure of the illustrative legs at spot 24,000 with 30 days to expiry, priced with Black–Scholes using each leg's implied volatility calibrated from its own quoted premium. A sign can flip as the underlying moves — the panels below show where. See Methodology.

Volatility impact

The iron butterfly is heavily short volatility because its two short options are at the money, where vega is greatest. A rise in implied volatility inflates those shorts and marks the position to a loss quickly, often faster than the equivalent condor because at-the-money vega dominates. A fall in implied volatility is the tailwind the structure wants, and it is why the butterfly is typically opened when at-the-money implied volatility is elevated — after a scare or into an event that is expected to resolve quietly. Selling into already-cheap volatility gives a smaller credit for the same narrow target and leaves little cushion if volatility then expands.

Time decay

Theta is powerful here. At-the-money options hold the most time value, so as a net seller of two of them the position decays quickly in its favour when price sits near the centre, and that decay steepens into the final days. The mirror image is severe negative gamma: the same nearness to the money that makes the decay fast makes the position lurch with every move near expiry, so a drift away from the centre in the last sessions can erase days of accumulated theta in a single move.

Practical examples

Lot sizes used above (NIFTY 75, BANKNIFTY 30) are those in force at the time of writing; NSE revises them periodically. Figures exclude brokerage, STT, exchange charges, stamp duty and GST, all of which materially affect small spreads.

Common mistakes

• Expecting to keep the full ₹24,750 — that amount is earned only at the exact centre strike, and the realistic outcome is a partial retention as price ends somewhere off centre.
• Placing the wings too far out to widen the credit, which raises the maximum loss because loss equals wing width minus credit, sometimes making the loss larger than the credit.
• Underestimating the negative gamma of two short at-the-money options, which makes the mark swing violently near expiry and can turn a winning position into a loss in one session.
• Selling the butterfly when at-the-money implied volatility is low, collecting a thin credit for a narrow target and leaving no cushion against a volatility rise.
• Holding through a directional catalyst, where a gap away from the centre both moves price off the peak and lifts volatility against the short options at once.
• Confusing it with an iron condor and expecting a broad profit zone; the butterfly profits only in a narrow band around a single strike.

Advantages & disadvantages

Adjustments & exits

• Rolling the untested wing or short in as price drifts, to re-centre the tent on the new price, which collects or pays premium and resets where the peak sits.
• Converting to an iron condor by rolling one short strike away from the centre, widening the profit zone at the cost of a smaller credit if the pin thesis weakens.
• Closing the position early once a large fraction of the credit has decayed, to bank the gain before late gamma can reverse it.
• Rolling the whole structure to a later expiry when tested, buying time but paying fresh spreads and extending the window of risk.

Adjustment is a decision about risk, not a way to rescue a losing view. See Adjustments and Exit Planning.

Professional usage

Desks treat an iron butterfly as a concentrated short-gamma, short-vega position pinned to a strike, often sized around large open-interest levels where dealer hedging can pull price toward the centre near expiry. They manage it as part of a book, hedging residual delta with futures and spreading many such positions across strikes and expiries so the aggregate, not one trade, carries the exposure. Retail traders lack the cross-margin and execution to leg in cheaply or to hold through the sharp mark swings, so the desk's tolerance for the position's gamma does not transfer to a single account.

Frequently asked questions

Voice search & related questions

Natural-language questions people ask about the Iron Butterfly.

Sources & references

• NSE — Options trading and margins
• Sheldon Natenberg — Option Volatility and Pricing
• Lawrence McMillan — Options as a Strategic Investment

Last reviewed 9 July 2026. Educational content only — not investment advice.