Option Premium

An option premium is the income received by an investor who sells or "writes" an option contract to another party. An option premium may also refer to the current price of any specific option contract that has yet to expire. For stock options, the premium is quoted as a dollar amount per share, and most contracts represent the commitment of 100 shares.

Investors who write, which means to sell in this case, calls or puts use option premiums as a source of current income in line with a broader investment strategy to hedge all or a portion of a portfolio. Option prices quoted on an exchange, such as the Chicago Board Options Exchange (CBOE), are considered premiums as a rule, because the options themselves have no underlying value.

The components of an option premium include its intrinsic value, its time value and the implied volatility of the underlying asset. As the option nears its expiration date, the time value will edge closer and closer to $0, while the intrinsic value will closely represent the difference between the underlying security's price and the strike price of the contract.

The main factors affecting an option's price are the underlying security's price, moneyness, useful life of the option and implied volatility. As the price of the underlying security changes, the option premium changes. As the underlying security's price increases, the premium of a call option increases, but the premium of a put option decreases. As the underlying security's price decreases, the premium of a put option increases, and the opposite is true for call options.

The moneyness affects the option's premium because it indicates how far away the underlying security price is from the specified strike price. As an option becomes further in-the-money, the option's premium normally increases. Conversely, the option premium decreases as the option becomes further out-of-the-money. For example, as an option becomes further out-of-the-money, the option premium loses intrinsic value, and the value stems primarily from the time value.

The time until expiration, or the useful life, affects the time value portion of the option's premium. As the option approaches its expiration date, the option's premium stems mainly from the intrinsic value. For example, deep out-of-the-money options that are expiring in one trading day would normally be worth $0, or very close to $0.

Implied volatility is derived from the option's price, which is plugged into an option's pricing model to indicate how volatile a stock's price may be in the future. Moreover, it affects the extrinsic value portion of option premiums. If investors are long options, an increase in implied volatility would add to the value. The opposite is true if implied volatility decreases. For example, assume an investor is long one call option with an annualized implied volatility of 20%. Therefore, if the implied volatility increases to 50% during the option's life, the call option premium would appreciate in value.