The Time Value and Other Elements of an Option Price

The Time Value of an Option
Generally, the longer the time remaining until an option’s expiration, the higher its premium will be. This is because the longer an option’s lifetime, greater is the possibility that the underlying share price might move so as to make the option in-the-money. All other factors affecting an option’s price remaining the same, the time value portion of an option’s premium will decrease (or decay) with the passage of time.
Note: This time decay increases rapidly in the last several weeks of an option’s life. When an option expires in-the-money, it is generally worth only its intrinsic value.


Volatility
Volatility is the tendency of the underlying security’s market price to fluctuate either up or down. It reflects a price change’s magnitude; it does not imply a bias toward price movement in one direction or the other. Thus, it is a major factor in determining an option’s premium. The higher the volatility of the underlying stock, the higher the premium because there is a greater possibility that the option will move in-the-money. Generally, as the volatility of an under-lying stock increases, the premiums of both calls and puts overlying that stock increase, and vice versa.
Higher volatility=Higher premium
Lower volatility = Lower premium


Interest rates
In general interest rates have the least influence on options and equate approximately to the cost of carry of a futures contract. If the size of the options contract is very large, then this factor may take on
some importance. All other factors being equal as interest rates rise, premium costs fall and vice versa. The relationship can be thought of as an opportunity cost. In order to buy an option, the buyer must either borrow funds or use funds on deposit. Either way the buyer incurs an interest rate cost. If interest rates are rising, then the opportunity cost of buying options increases and to compensate the buyer premium costs fall. Why should the buyer be compensated? Because the option writer receiving the premium can place the funds on deposit and receive more interest than was previously anticipated. The situation is reversed when interest rates fall – premiums rise. This time it is the writer who needs to be compensated.