For an option contract, expiration is the date on which the contract expires. The option holder must elect to exercise the option or allow it to expire worthless. In finance, an option is a contract whereby one party (the holder or buyer) has the right but not the obligation to exercise a feature of the contract (the option) on or before a future date (the exercise date or expiry). ... All the textbooks define a contract as either a promise or an agreement that is enfored or recognised by the law. ...

Typically, option contracts expire according to a pre-determined calendar. For instance, for U.S. exchange-listed equity option contracts, the expiration date is always on the Saturday that follows the third Friday of the month, unless that Friday is a market holiday, in which case the expiration is on the Friday. A calendar is a system for naming periods of time, typically days. ... This article is about concept of equity in Anglo-American jurisprudence. ... Saturday is the seventh (sixth in some countries) day of the week, between Friday and Sunday. ... Friday is the fifth day of the week, falling between Thursday and Saturday. ...