When purchasing a time spread, the investor should pay attention to not only the movement of the stock price, but also the movement of volatility. It plays a very large roll in the price of a time spread, which is an excellent way to take advantage of anticipated volatility movements in a hedged fashion.



Option Volatility

Since the time spread is composed of two options, the investor should understand the role of volatility in options as well as in time spreads. Let us start with option volatility.

We measure an option's volatility component by a term called Vega. Vega, one of the components of the pricing model, measures how much an option's price will change with a one-point (or tick) change in implied volatility. Based on present data, the pricing model assigns the Vega for each option at different strikes, different months and different prices of the stock.

Vega is always given in dollars per one tick volatility change. If an option is worth $1.00 at a 35 implied volatility and it has a .05 Vega, then the option will be worth $1.05 if implied volatility were to increase to 36 (up one tick) and $.95 if the implied volatility were to decrease to 34 (down one tick).

Keep these facts in mind as we continue to discuss Vega:

1. Vega measures how much an option price will change as volatility changes.

2. Vega increases as you look at future months and decreases as you approach expiration.

3. Vega is highest in the at-the-money options.

4. Vega is a strike-based number. It applies whether the strike is a call or a put.

5. Vega increases as volatility increases and decreases as volatility decreases.

It is important to note that an option's volatility sensitivity increases with more time to expiration. Further out-month options have higher Vegas than the Vegas of the near term options. The further out you go over time, the higher the Vegas become. Although increasing, they do not progress in a linear manner. When you check the same strike price out over future months you will notice that Vega values increase as you move out over future months.

The at-the-money strike in any month will have the highest Vega. As you move away from the at-the-money strike in either direction, the Vega values decrease and continue to decrease the further away you get from the at-the-money strike. Remember, Vega (an option's volatility component value) is highest in at-the-money, out-month options. Vega decreases the closer you get to expiration and the further away you move from the at-the-money strike.

The chart below shows Vega values for QCOM options. Observe the important elements. The stock price is constant at 68.5. Volatility is constant at 40. Time progresses from June to January. Finally, the strike price changes from 50 through 80. Notice the increasing pattern as you go out over time and how the value decreases as you move away from the at-the-money strike.

Chart 3- Vega

Stock Price 68.5 Vol. 40

StrikeJuneJulyOctoberJanuary

50 0.008.064.114

55.004.030.102.153

60.023.063.135.184

65.053.090.157.205

70.056.094.165.215

75.032.077.154.213

80.011.052.142.203

Another important fact about Vega is that it is a strike-based number. This means that the Vega number does not differentiate between put and call. Vega tells the volatility sensitivity of the strike regardless of whether you are looking at puts or calls. Therefore, the Vega number of a call and its corresponding put are identical.

The chart below shows the Vega values for calls and the corresponding puts. As you can see, these values match up in every instance.

Chart 6

Strike Price-Call Vega-Put Vega

June

60.023.023

65.053.053

70.056.056

July

60.063.063

65.090.090

70.094.094

October

60.135.135

65.157.157

70.165.165

January

60.184.184

65.205.205

70.215.215

Vega can also calculate how much a specific option's price will change with a movement in implied volatility. You simply count how many volatility ticks implied volatility has moved. Multiply that number times the Vega and either add it (if volatility increased) to the option's present value or subtract it (if volatility decreased) from the option's present value to obtain the option's new value under the new volatility assumption. The calculation works on individual options and can analyze the value of the time spread.

Apply Vega to Time Spreads

Now, let us apply the concepts of Vega to the Time Spread. When you apply the Vega concept to time spreads, you observe that as implied volatility increases, the value of the time spread increases. This is because the out-month option, with the higher Vega will increase more than the closer month option with the lower Vega. That widens or increases the spread.

The chart below shows a time spread and its reaction to increasing volatility. Each time that implied volatility increases, the value of the time spreads increase. This increase would naturally favor the buyer.

Chart 4

Stock Price $Vol.June / July 65Oct / July 65

65.5301.092.09

65.5401.432.75

65.5501.773.41

65.5602.114.05

65.5702.494.60

If an investor bought the time spread at low volatility and within a few weeks volatility had increased and pushed the spread price higher, the investor could sell the spread at a profit even before expiration.

Of course, the Vega can also demonstrate the opposing effect. As implied volatility decreases, the spread tightens or decreases in value. As volatility comes down, the out-month option with its higher Vega will lose value more quickly than will the nearer month option with its lower Vega. In the chart below, you will see how decreasing volatility affects the time spread's value.

Chart 5

Stock Price $Vol.June / July 65Oct / July 65

65.5702.494.60

65.5602.114.05

65.5501.773.41

65.5401.432.75

65.5301.092.09

Glance back to Charts 4 and 5. Take note that the stock price is constant. The changes in the price of the spreads are due to the change in volatility.

We discussed how to use Vega to calculate an option's price when volatility changes. The same calculation method works for time spreads but the calculation is slightly more difficult.