In a vertical spread, what is the condition for the options involved?

In a vertical spread, the essential condition is that the options involved must have the same expiration date. This characteristic is crucial because it allows the trader to take advantage of the price movements of the underlying asset over a specific period rather than dealing with different time frames that could introduce additional variables such as differing levels of time decay or implied volatility.

Having the same expiration date means that the spread is primarily affected by the same market conditions and time elements. This alignment ensures that the gains or losses from one leg of the spread directly correlate with the other, allowing for a more efficient management of risk and potential profit. Additionally, both options will experience similar impacts from changes in the price of the underlying asset, as they share the same expiration period.

The other options mentioned do not apply to the nature of vertical spreads. Different expiration dates, different markets, or varying underlying assets would create a misalignment that detracts from the intended function of the vertical spread, which is to capitalize on the relative price movement of the same underlying asset within a specified timeframe.