In finance, an option is a contract which gives the buyer (the owner) the right, but not the obligation, to buy or sell an underlying asset or instrument at a specified strike price on or before a specified date. The seller has the corresponding obligation to fulfill the transaction—that is to sell or buy—if the buyer (owner) “exercises” the option. The buyer pays a premium to the seller for this right. An option that conveys to the owner the right to buy something at a certain price is a “call option“; an option that conveys the right of the owner to sell something at a certain price is a “put option“. Both are commonly traded, but for clarity, the call option is more frequently discussed. Options valuation is a topic of ongoing research in academic and practical finance. In basic terms, the value of an option is commonly decomposed into two parts:
- The first part is the “intrinsic value“, defined as the difference between the market value of the underlying and the strike price of the given option.
- The second part is the “time value”, which depends on a set of other factors which, through a multivariable, non-linear interrelationship, reflect the discounted expected value of that difference at expiration.
Although options valuation has been studied since the 19th century, the contemporary approach is based on the Black–Scholes model, which was first published in 1973.
Options contracts have been known for many centuries. However, both trading activity and academic interest increased when, as from 1973, options were issued with standardized terms and traded through a guaranteed clearing house at the Chicago Board Options Exchange. Today, many options are created in a standardized form and traded through clearing houses on regulated options exchanges, while other over-the-counter options are written as bilateral, customized contracts between a single buyer and seller, one or both of which may be a dealer or market-maker. Options are part of a larger class of financial instruments known as derivative products or simply derivatives.