A non-standard financial option with no fixed maturity and no exercise limit. While the life of a standard option can vary from a few days to several years, a perpetual option (XPO) can be exercised at any time. Perpetual options are considered an American option; European options can be exercised only on the option’s maturity date.

Also referred to as "non-expiring options" or "expirationless options."

For investors, perpetual options represent the highest ratio of possible risk/reward payoff compared to existing financial products. Perpetual options are viewed as “plain vanilla” options. For many investors they represent an advantage over other instruments (where dividends and/or voting rights are not a high priority) because the strike price on a perpetual option enables the holder to choose the buy or sell price point instead of having to select a singular stock price. In addition, XPOs can be preferable to standard options because they eliminate the expiration risk.