Six primary factors influence options pricing: the underlyingÂ price, strike price, time until expiration, volatility, interest rates and dividends.Â
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Figure 2:Â Six factors that influence option pricing are shown on the top row of the chart. As indicated, the underlying price and strike price determine the intrinsic value; the time until expiration and volatility determine the probability of a profitable move; the interest rates determine the cost of money; and dividends can cause an adjustment to share price. 
Underlying Price
The most influential factor on an option premium is the current market price of the underlying asset. In general, as the price of the underlying increases, call prices increase and put prices decrease. Conversely, as the price of the underlying decreases, call prices decrease and put prices increase.
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If underlying prices ...  Call prices will ...  Put prices will ... 
Increase  Increase  Decrease 
Decrease  Decrease  Increase 
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Strike Price
TheÂ strike priceÂ determines if the option has anyÂ intrinsic value. Remember, intrinsic value is the difference between the strike price of the option and the current price of the underlying asset. The premium typically increases as the option becomes further inthemoney (where the strike price becomes more favorable in relation to the current underlying price). The premium generally decreases as the option becomes more outofthemoney (when the strike price is less favorable in relation to the underlying security).
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Premiums increase as options become further inthemoney. 
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Time Until Expiration
The longer an option has until expiration, the greater the chance it will end up inthemoneyÂ (profitable). As expiration approaches, the option's time value decreases. As a general rule, an option loses onethird of its time value during the first half of its life, and twothirds of its value during the second half. The underlying asset's volatility is a factor in time value: If the underlying is highly volatile, you can reasonably expect a greater degree of price movement before expiration. The opposite holds true where the underlying exhibits low volatility: The time value will be lower if the underlying price is not expected to move much.
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The longer the time until expiration, the higher the option price. 
The shorter the time until expiration, the lower the option price. 
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Expected Volatility
VolatilityÂ is the degree to which price moves, whether it goes up or down. It is a measure of the speed and magnitude of the underlying's price changes.Â Historical volatilityÂ refers to the actual price changes that have been observed over a specified time period. Options traders can evaluate historical volatility toÂ determine possible volatility in the future.Â Implied volatility, on the other hand, is a forecast of future volatility and acts as an indicator of the current market sentiment. While implied volatility can be difficult to quantify, option premiums are generally higher if the underlying exhibits higher volatilityÂ because it will have higher expected price fluctuations.
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The greater the expected volatility, the higher the option value. 
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Interest RatesÂ Â
Interest rates and dividends have small, but measurable, effects on option prices. In general, as interest rates rise, call premiums increase and put premiums decrease. This is because of the costs associated with owning the underlying: The purchase incurs either interest expense (if the money is borrowed) or lost interest income (if existing funds are used to purchase the shares). In either case, the buyer will have interest costs.
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If interest rates ...  Call prices will ...  Put prices will ... 
Rise  Increase  Decrease 
Fall  Decrease  Increase 
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Dividends
Dividends can affect option prices because the underlying stock's price typically drops by the amount of any cash dividend on the exdividend date. As a result, if the underlying's dividend increases, call prices will decrease and put prices will increase. Conversely, if the underlying's dividend decreases, call prices will increase and put prices will decrease.
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If dividends ...  Call prices will ...  Put prices will ... 
Rise  Decrease  Increase 
Fall  Increase  Decrease 
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Options Pricing: Distinguishing Between Option Premiums and Theoretical Value

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