In order to stack the odds in your favor when developing options strategies, it is important to clearly distinguish between two types of volatility:
implied and historical. Implied volatility (IV) as we have already noted, is the measure of volatility that is embedded in an option’s price. In addition, each options contract will have a unique level of implied volatility that can be computed using an option pricing model. All else being equal, the greater an underlying asset’s volatility, the higher the level of IV. That is, an underlying asset that exhibits a great deal of volatility will command a higher option premium than an underlying asset with low volatility.
To understand why a volatile stock will command a higher option premium, consider buying a call option on XYZ with a strike price of 50 and expiration in January (the XYZ January 50 call) during the month of December. If the stock has been trading between $40 and $45 for the past six weeks, the odds of the option rising above $50 by January are relatively slim. As a result, the XYZ January 50 call option will not carry much value. But say the stock has been trading between $40 and $80 during the past six weeks and sometimes jumps $15 in a single day. In that case, XYZ has exhibited relatively high volatility, and therefore the stock has a better chance of rising above $50 by January. A call option, which gives the buyer the right to purchase the stock at $50 a share, will have better odds of being in-the-money and as a result will command a higher price if the stock has been exhibiting higher levels of volatility.
Options traders understand that stocks with higher volatility have a greater chance of being in-the-money at expiration than low-volatility stocks. Consequently, all else being equal, a stock with higher volatility will have more expensive option premiums than a low-volatility stock. Mathematically, the difference in premiums between the two stocks owes to a difference in implied volatility—which is computed using an option pricing model like the one developed by Fischer Black and Myron Scholes, the Black-Scholes model. Furthermore, IV is generally discussed as a percentage. For example, the IV of the XYZ January 50 call is 25 percent. Implied volatility of 20 percent or less is considered low. Extremely volatile stocks can have IV in the triple digits.
Sometimes traders and analysts attempt to gauge whether the implied volatility of an options contract is appropriate. For example, if the IV is too high given the underlying asset’s future volatility, the options may be overpriced and worth selling. On the other hand, if IV is too low given the outlook for the underlying asset, the option premiums may be too low, or cheap, and worth buying. One way to determine whether implied volatility is high or low at any given point in time is to compare it to its past levels. For example, if the options of an underlying asset have IV in the 20 to 25 percent range during the past six months and then suddenly spike up to 50
percent, the option premiums have become expensive.
Statistical volatility (SV) can also offer a barometer to determine whether an options contract is cheap (IV too low) or expensive (IV too high). Since SV is computed as the annualized standard deviation of past prices over a period of time (10, 30, 90 days), it is considered a measure of historical volatility because it looks at past prices. If you don’t like math, statistical volatility on stocks and indexes can be found on various web sites like the Optionetics.com Platinum site. SV is a tool for reviewing the past volatility of a stock or index. Like implied volatility, it is discussed in terms of percentages. Comparing the SV to IV can offer indications regarding the appropriateness of the current option premiums. If the implied volatility is significantly higher than the statistical volatility, chances are the options are expensive. That is, the option premiums are pricing in the expectations of much higher volatility going forward when compared to the underlying asset’s actual volatility in the past. When implied volatility is low relative to statistical volatility, the options might be cheap. That is, relative to the asset’s historical volatility, the IV and option premiums are high. Savvy traders attempt to take advantage of large differences between historical and implied volatility. In later chapters, we will review some strategies that show how.
implied and historical. Implied volatility (IV) as we have already noted, is the measure of volatility that is embedded in an option’s price. In addition, each options contract will have a unique level of implied volatility that can be computed using an option pricing model. All else being equal, the greater an underlying asset’s volatility, the higher the level of IV. That is, an underlying asset that exhibits a great deal of volatility will command a higher option premium than an underlying asset with low volatility.
To understand why a volatile stock will command a higher option premium, consider buying a call option on XYZ with a strike price of 50 and expiration in January (the XYZ January 50 call) during the month of December. If the stock has been trading between $40 and $45 for the past six weeks, the odds of the option rising above $50 by January are relatively slim. As a result, the XYZ January 50 call option will not carry much value. But say the stock has been trading between $40 and $80 during the past six weeks and sometimes jumps $15 in a single day. In that case, XYZ has exhibited relatively high volatility, and therefore the stock has a better chance of rising above $50 by January. A call option, which gives the buyer the right to purchase the stock at $50 a share, will have better odds of being in-the-money and as a result will command a higher price if the stock has been exhibiting higher levels of volatility.
Options traders understand that stocks with higher volatility have a greater chance of being in-the-money at expiration than low-volatility stocks. Consequently, all else being equal, a stock with higher volatility will have more expensive option premiums than a low-volatility stock. Mathematically, the difference in premiums between the two stocks owes to a difference in implied volatility—which is computed using an option pricing model like the one developed by Fischer Black and Myron Scholes, the Black-Scholes model. Furthermore, IV is generally discussed as a percentage. For example, the IV of the XYZ January 50 call is 25 percent. Implied volatility of 20 percent or less is considered low. Extremely volatile stocks can have IV in the triple digits.
Sometimes traders and analysts attempt to gauge whether the implied volatility of an options contract is appropriate. For example, if the IV is too high given the underlying asset’s future volatility, the options may be overpriced and worth selling. On the other hand, if IV is too low given the outlook for the underlying asset, the option premiums may be too low, or cheap, and worth buying. One way to determine whether implied volatility is high or low at any given point in time is to compare it to its past levels. For example, if the options of an underlying asset have IV in the 20 to 25 percent range during the past six months and then suddenly spike up to 50
percent, the option premiums have become expensive.
Statistical volatility (SV) can also offer a barometer to determine whether an options contract is cheap (IV too low) or expensive (IV too high). Since SV is computed as the annualized standard deviation of past prices over a period of time (10, 30, 90 days), it is considered a measure of historical volatility because it looks at past prices. If you don’t like math, statistical volatility on stocks and indexes can be found on various web sites like the Optionetics.com Platinum site. SV is a tool for reviewing the past volatility of a stock or index. Like implied volatility, it is discussed in terms of percentages. Comparing the SV to IV can offer indications regarding the appropriateness of the current option premiums. If the implied volatility is significantly higher than the statistical volatility, chances are the options are expensive. That is, the option premiums are pricing in the expectations of much higher volatility going forward when compared to the underlying asset’s actual volatility in the past. When implied volatility is low relative to statistical volatility, the options might be cheap. That is, relative to the asset’s historical volatility, the IV and option premiums are high. Savvy traders attempt to take advantage of large differences between historical and implied volatility. In later chapters, we will review some strategies that show how.
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