Iron Butterfly

An iron butterfly is an options strategy that profits when the price of the underlying stays close to one level until expiry. It’s built from four options with the same expiry:

• Sell an at-the-money call option
• Sell an at-the-money put option at the same strike
• Buy an out-of-the-money call above that strike
• Buy an out-of-the-money put below it, the same distance away

The two options you sell form a short straddle, which collects premium. The two options you buy are the “wings”, which cap the loss if the price moves sharply. You receive more for the options you sell than you pay for the wings, so the trade starts with a net credit.

Net credit = premium from the two sold options – premium for the two wings

Breakevens at expiry = middle strike ± net credit

Maximum profit = net credit × lot size

Maximum loss = (wing width – net credit) × lot size

Worked example: an iron butterfly on an index

Say an index is at 20,000 with seven days to expiry, and the lot size is 50 (hypothetical numbers):

• Net credit: (144 + 144) – (42 + 40) = ₹206 per unit
• Wing width: 300 points on each side
• Maximum profit: 206 × 50 = ₹10,300, if the index closes exactly at 20,000
• Maximum loss: (300 – 206) × 50 = ₹4,700, if the index closes at or beyond 19,700 or 20,300
• Breakevens: 20,000 – 206 = 19,794 and 20,000 + 206 = 20,206

Here’s the profit or loss per lot at expiry:

The payoff looks like a tent: highest at the middle strike, falling away on both sides, and flat beyond the wings. That shape is where the name comes from.

Iron butterfly vs short straddle

An iron butterfly is a short straddle with protection bought on both sides. Using the same example:

The wings cost you some premium and narrow the breakevens, but they turn an open-ended risk into a known, fixed one. That’s why many traders who sell straddles prefer the iron butterfly.

Iron butterfly vs iron condor

Both are four-leg, defined-risk strategies that profit from time decay. The iron butterfly pays more but needs the price to stay closer to the middle. The iron condor pays less but gives the price more room.

How the Greeks behave

• Time decay (theta) works for you. The position gains as time value drains away, fastest in the final days before expiry.
• Rising volatility (vega) works against you. If implied volatility rises, all four options gain value, and the position, being net short, loses. A fall in IV helps.
• Big moves hurt (negative gamma). The position starts close to delta-neutral, but a move away from the middle strike quickly turns it against you, until the wings kick in.

See net Greeks for how the four legs combine.

When traders use an iron butterfly

• After a big event. Once results or a policy announcement are out, implied volatility usually drops and the market often settles. Selling premium then, with the risk capped, is a common use.
• Near expiry in a quiet market. The strategy collects time decay fastest close to expiry, when the price has less time to wander. That is also when gamma risk is highest, so the capped loss matters.
• Around a strike the market keeps returning to. Traders sometimes centre an iron butterfly on a strike with heavy open interest or near max pain, where they expect the price to settle.

Risks and practical points

• A narrow profit zone. The maximum profit only comes if the index closes right at the middle strike. In most outcomes, you keep part of the credit, not all of it.
• The maximum profit is rarely reached. In the example, you risk ₹4,700 to make up to ₹10,300, which looks attractive, but the index has to finish almost exactly at 20,000 to earn all of it. Judge the trade on its breakevens and probability, not just the maximum profit.
• Four legs, four sets of charges. Opening and closing means eight orders, each paying brokerage, STT and exchange charges. See gross P&L vs net P&L.
• Leg risk. If you enter the legs one by one and the market moves in between, your prices can be worse than planned. Placing all four together as a basket order helps.
• Managing a move. If the index moves towards one of the wings, traders often close early to protect part of the credit rather than wait for the maximum loss.

Long iron butterfly

The reverse trade, a long iron butterfly, buys the at-the-money call and put and sells the wings. It’s a net debit, and it profits if the price moves far enough from the middle strike in either direction, with both the maximum profit and the maximum loss capped. It’s a cheaper, limited-risk alternative to buying a straddle.

To build an iron butterfly from Stolo’s pre-built strategies, see its payoff and breakevens, and check its net Greeks before you trade, use Stolo’s Option Strategy Builder. To watch how time decay works across all four legs together, use Stolo’s options premium decay tool.