Short Butterfly

A short call butterfly sells one call at a lower strike, purchases two calls at a middle strike, and sells one call at a higher strike. All options have the same underlying, expiration, and contract size, and the strikes are equally spaced. The position receives a credit and has its greatest expiration profit at or beyond either outer strike. Its greatest loss occurs at the middle strike.

This construction reverses the long call butterfly. It benefits from a sufficiently large movement away from the center, but the short outer calls cap the expiration profit rather than allowing it to continue growing with a larger movement.

Construction and example

A hypothetical example uses SPY at $750 and calls with 45 days remaining. One complete position uses these standard 100-share contracts:

The outer calls receive $42.50 per share together, while the two middle calls cost $37. The net credit is $5.50 per share, or $550. In contract amounts, the $4,250 received exceeds the $3,700 paid by that amount. Four contracts form three distinct legs, since the middle leg comprises two contracts of the same series.

Expiration payoff

At $725 or below at expiration, all calls have zero payoff and the $550 credit is profit. Between $725 and $750, the lower short call is the only option with intrinsic value. Its obligation grows by $100 for each $1 rise, exhausting the credit at $730.50.

At $750, the lower short call has a $25 per-share payoff, while the purchased middle calls and higher short call have none. The $25 per-share obligation exceeds the $5.50 per-share credit by $19.50 per share. For the complete position, the $2,500 obligation less the $550 credit gives the maximum loss of $1,950.

Above $750, the two purchased calls gain $200 together for each additional $1 rise, while the lower short call’s obligation increases by $100. The result improves and reaches the upper break-even at $769.50. At $775, the higher short call begins offsetting further improvement. At and above that strike, equal spacing makes the net option payoff zero, leaving the $550 credit as the maximum profit.

The position is unprofitable between the two break-evens and profitable outside them, with profit capped at or beyond the outer strikes. An equivalent inverse one-to-two-to-one construction using puts at equally spaced strikes has the same combined expiration payoff shape; its premium credit determines the profit level.

Value before expiration

Near $750, the two purchased calls retain value for possible movements away from the central loss region. A sufficiently large rise can make their gains outweigh the lower short call’s increasing obligation, while a decline can reduce that obligation. If SPY remains at the middle strike as expiration approaches, the position tends toward its greatest loss.

Higher implied volatility can help near the middle by increasing the value of outcomes away from that minimum. Outside the wings, it also increases the possibility of returning to the loss region, so its effect can reverse. Time passing can similarly be unfavorable near the center but favorable when the underlying remains well beyond an outer strike. Relative changes in the three strikes’ IVs can alter these effects.

Closing repurchases the outer calls and sells the two middle calls. A signed net closing cost below the $5.50 per-share opening credit produces a profit. The price of each leg includes its remaining time value, so the early closing result need not equal the expiration result at the same underlying price.

Exercise, assignment, and execution

SPY calls permit early exercise. The lower $725 short call can be in the money while both purchased $750 calls are still out of the money. Its assignment sells 100 shares and may leave short stock alongside the purchased calls. Either short outer call can be assigned independently, while the long calls retain their separate purchase rights.

Above all strikes at expiration, exercise of both purchased calls can supply shares for both short-call deliveries if the contracts are exercised and assigned as expected. Near a strike, different exercise decisions can leave shares instead. Any stock retained after the options end has its own subsequent profit or loss and account requirements.

A complex closing order maintains the intended one-to-two-to-one ratio for each filled package and can specify a net price limit. It does not guarantee a complete fill or combine exercise decisions across contracts. Closing option positions through market trades can also preserve time value that immediate exercise would not realize.

Payoff formulas

Let $K_L<K_M<K_H$ be equally spaced strikes, with $w=K_M-K_L=K_H-K_M$, and let $c$ be the credit per share. For final underlying price $S_T$, $q$ complete butterflies, and multiplier $M$:

The two middle-call payoffs are added, the outer-call obligations subtracted, and the opening credit included. For $0<c<w$:

The maximum loss occurs at $K_M$, while the outer regions earn the full credit. Equal spacing is essential to the zero combined option payoff above the highest strike. With unequal wings, that region must be evaluated from the full formula rather than assumed to cancel. Scaling complete butterflies changes the dollar amounts without moving the break-evens.