An option or futures spread whereby the number of contracts bought (or long) is not equal to the number of contracts sold (or short). The difference between the number of contracts on the two legs of a position create the spread.

A ratio spread is a neutral options strategy involving a simultaneous position in an unequal number of long and short options. Similar to a vertical spread, a ratio spread involves buying and selling options on the same underlying with different strike prices and the same expiration date.

The ratio spread is also called a variable spread.

It is the opposite of a back spread.