Iron Butterfly

An iron butterfly is a four-leg net-credit strategy made from a short call and a short put at the same middle strike, plus a long put below and a long call above that strike. All four options share the same expiration date.

Functionally, it is a defined-risk version of a short straddle. The short at-the-money call and put create the premium intake, while the long wings cap the risk on both sides.

The defining feature of the iron butterfly is that both short options sit at the same center strike. That creates the highest potential premium intake, but it also means the maximum profit occurs only if the underlying finishes exactly at, or very near, that middle strike at expiration.

Compared with an iron condor, an iron butterfly is more concentrated around one strike. It generally collects a larger credit relative to wing width, but its profitable zone is narrower because the short call and short put are both centered at the same strike rather than separated into a range.

The trade is opened for a credit, and that credit is the maximum possible gain. Maximum profit occurs if the underlying settles exactly at the short strike at expiration, causing both short options to expire at the money and all extrinsic value to disappear.

As price moves away from the center strike, the position gradually gives back profit. Once price moves beyond either breakeven, the trade turns into a loss. That loss is capped once the underlying moves beyond either long wing.

The lower breakeven is the center strike minus the total credit received. The upper breakeven is the center strike plus the total credit received. Between those two points, the trade is profitable at expiration, but the maximum gain only occurs at the center strike itself.

Theta: The position generally benefits from time decay, especially when price stays very close to the short strike and the premium in the short options erodes steadily.

Vega: The iron butterfly is typically short vega, so it generally benefits when implied volatility falls after entry and loses value when implied volatility rises.

Gamma: It is also short gamma. Because the position is centered at a single strike, even modest movement away from that strike can change the P&L quickly, especially late in the cycle.

The expiration payoff graph is only the final snapshot. Before expiration, the trade’s mark-to-market value is smoother because all four options still contain time value, and that value shifts with price, implied volatility, and time to expiry.

In practice, an iron butterfly can often be managed before expiration if decay works quickly or if volatility contracts. But because the trade is highly centered, it can also become stressed faster than a wider iron condor when price starts drifting away from the middle strike.