A spread is a combination of any two or more of the same type of options (two calls or two puts, for instance) on same underlying asset. A vertical spread specifies that the options have the same maturity month. Finally, a long vertical spread designates a position for which one has bought a low-exercise-price call (or a low-exercise put) that both mature in the same month. A long vertical spread is also known as a bull spread because of the bullish market expectation of the investor who enters into it. The investor limits the profit potential in selling the high-exercise-price call (or put). It is a popular position when is expected that the market will more likely go up than down. The profit potential is limited up to the higher exercise price. The loss potential is limited down to the lower exercise price. The effect of time decay is mixed. And the market expectation is cautiously bullish.