A Butterfly spread is an options trading strategy involving three strike prices that has both limited risk and limited profit potential. A trader establishes a long call butterfly by: buying one call at the lowest strike price, writing two calls at the middle strike price, and buying one call at the highest strike price. A long put butterfly is established by: buying one put at the highest strike price, writing two puts at the middle strike price, and buying one put at the lowest strike price. For example, a long call butterfly might be: buying 1 XYZ May 55 call, writing 2 XYZ May 60 calls and buying 1 XYZ May 65 call.
The total cost of a long butterfly spread is calculated by multiplying the net debit (cost) of the strategy by the number of shares each contract represents. A butterfly will break even at expiration if the price of the underlying is equal to one of two values. The first break-even value is calculated by adding the net debit to the lowest strike price. The second break-even value is calculated by subtracting the net debit from the highest strike price. The maximum profit potential of a long butterfly is calculated by subtracting the net debit from the difference between the middle and lower strike prices. The maximum risk is limited to the net debit paid for the position.
Butterfly spreads achieve their maxim profit potential at expiration if the price of the underlying is equal to the middle strike price. The maximum loss is realized when the price of the underlying is below the lowest strike or above the highest strike at expiration.