Box Spread

A box spread, commonly called a long box strategy, is an options arbitrage strategy that combines buying a bull call spread with a matching bear put spread. A box spread can be thought of as a vertical spread, but one that must have the same strike prices and expiration dates. A box spread is optimally used when the spreads themselves are underpriced with respect to their expiration values. When the trader believes the spreads are overpriced, they may employ a short box, which uses the opposite options pairs, instead. The concept of a box comes to light when one considers the purpose of the two vertical, bull call and bear put, spreads involved.