Option Theta

Option theta, often referred to as time decay, measures the rate at which an option's value decreases as it approaches its expiration date. All else being equal, the value of an option erodes over time because there is less opportunity for the underlying asset to reach a favorable price.

Theta is typically expressed as a negative number for long options, indicating a loss of value over time. For short options, theta is positive, representing the income earned from the passage of time.

This decay is not linear; it accelerates as the option nears expiration, especially for at-the-money options. Traders must account for theta when constructing strategies, as it represents the cost of holding a position.

In crypto markets, where options can have very high premiums, theta decay can be a significant factor in strategy profitability. Managing theta is essential for those who sell volatility or engage in multi-leg option strategies.