Option Greeks show how an option’s value will change when the underlying stock price, time to expiration, or the stock’s volatility change. Every option Greek is represented by a single number. Every option Greek tells us something different about our trade. If you understand these five option Greeks, you will never feel lost when trading options again. In this article I’m going to explain the five option Greeks, implied volatility, and delta hedging in plain language. Have you just started learning about options?
Start with our options trading guide for beginners . We use one example all the way through. It is a call option on a $100 stock. The strike is $100. There are 30 days left. Implied volatility is 30%.
What Are Option Greeks and Why Do They Matter?
The Greeks are the dashboard of an option. The price tells you what you pay. The Greeks tell you what happens next. Four of them matter most: Delta, Gamma, Theta and Vega. A fifth, Rho, matters less. The Options Industry Council defines delta as the expected change in option value when the stock moves. It defines Vega as the expected change when implied volatility moves. Why care? Two traders can own the same option and face very different risks. One loses to time. The other loses to falling volatility. The Greeks show which.
Greek What it measures Example
Delta Option price change for a $1 stock move 0.53
Gamma Change in delta for a $1 stock move 0.046
Theta Option value lost each day to time -$0.06
Vega Price change for 1 point of implied volatility $0.11
Rho Price change for 1-point of interest rates $0.04
These numbers come from our example call, which costs $3.59. Remember them. We will use them below.
Delta and Gamma: How Option Prices React to Price Moves
The rate at which an option changes value is called delta. A call option has a delta range from zero to one. A call option with an “at-the-money” strike price will have a delta close to 0.50. In fact, a call option with a “deeply in-the-money” strike price will move very close to the movement of the underlying asset. A call option with a “far out-of-the-money” strike price will move very little. Many traders also use delta as a general estimate of whether or not their option will finish in the money. However, delta should be viewed only as an approximation.
Now we will look at an example. We have a call that costs $3.59 with a delta of 0.53. The stock goes up $1 to $101. Based on delta, the option should go up approximately 53 cents. The option goes up 56 cents and is now valued at $4.15. What explains the additional 3 cents? Gamma. Gamma represents the rate at which delta changes. With a value of 0.046, every time the stock moves $1, delta increases by approximately 0.05. Therefore, delta is now 0.58. The next $1 gain in the stock price results in a greater increase in the option price than the first $1 gain. If the stock declines by $1 to $99, the call declines to $3.08. This represents a decline of 51 cents.
Image 1: Delta and gamma for our example call. The teal line is delta. It rises from near 0 on the left to near 1 on the right. It reads 0.53 at the $100 strike. The orange line is gamma. It peaks near the strike at 0.046 and fades on both sides.
Gamma is highest when an option is at the money and close to expiry. That is where your position changes fastest. Buyers of options gain from gamma. Sellers carry its risk. Our straddle guide shows a strategy built around it.
Theta and Vega: How Time and Volatility Affect Options
Theta is the cost of waiting. Our call loses about 6 cents a day, so its theta is -0.06. Buyers of calls and puts both pay it. The loss is not even. It speeds up near expiry. With 60 days left, our call is worth $5.17. At 30 days it is $3.59. At 7 days it is $1.70. With one day left it is $0.63. It loses about 32 cents that day. Time works against the buyer.
The curve is the cost of our at-the-money call option as it approaches its expiration date, moving from sixty days prior to expiration on the left to zero days prior to expiration on the right. At five specific intervals along this curve, we have included the cost of the call option and the daily theta for each of these times. The curve drops off quickly during the final week before expiration.
The value of an option that relates to its sensitivity to changes in implied volatility (Vega) is the price we pay for the uncertainty of whether or not our trade will be successful. The Vega for our call is.11. Therefore, when the implied volatility increases by one percentage point, our option will gain.11. When the implied volatility decreases by one percentage point, our option will lose.11. The options with the largest Vega are those that are traded “at-the-money.” It is common for time and implied volatility to move in opposite directions.
A buyer can be right on direction and still lose money, because implied volatility fell .
Rho, the fifth Greek, measures sensitivity to interest rates. For our example call it is only 0.04. It matters mostly for long-dated options.
What Is Implied Volatility and How Do You Read It?
The stock price movement that the market predicts, called implied volatility (IV), is based on option prices and not on historical charts. The IV is expressed as an annual percentage. A higher IV indicates that the options are more expensive; while a lower IV indicates that the options are less expensive. Do not mistake IV with historical volatility. Historical volatility measures how much the stock has actually moved. When you compare both, if IV is significantly higher than historical volatility, then the options appear to be expensive.
IV is an indicator that shows how much money people think they can make from a stock. Before a company reports earnings, traders will buy options on the company’s stock to either protect themselves from losing money if the earnings are bad, or to try and make some money if the earnings are good.
When traders buy options, the IV goes up. Once the earnings are announced, everyone knows what happened and the IV goes down quickly. This is referred to by traders as IV crush. Let’s look at our example again. Our call option costs $3.59 when IV is 30%. Before the earnings announcement, the IV increases to 55% and the same call option now costs $6.44. The earnings announcement comes out. Nothing changes in the price of the stock. The IV goes back down to 30%. The call option is once again valued at $3.59. You have lost 44% of your investment without any change in the price of the stock.
Image 3: Implied volatility and the premium. The first bar shows our call at 30% IV, costing $3.59. The second shows it before earnings at 55% IV, costing $6.44. The third shows it after earnings, when IV is back at 30% and the price returns to $3.59.
A common rule, noted by InvestingLive , is to sell options when IV is high and buy them when IV is low. Treat it as a rule of thumb, not a promise.
What Is Delta Hedging and How Does It Work?
Delta hedging is a strategy used to offset the delta of an option by purchasing or selling a certain number of shares. This creates a position that is insensitive to minor fluctuations in price, and traders refer to this type of position as delta neutral.
Example: You have purchased 10 call options contracts. Since each option represents 100 shares of the underlying stock, you are long on 1,000 shares. Your delta is.53 per option; therefore, your options behave as though they represent 530 shares of the underlying stock. In order to achieve a “delta neutral” position, you must short sell 530 shares of the underlying stock. When the underlying stock increases in value by $1, your options will increase in value by approximately $560.
On the other hand, when the underlying stock increases in value by $1, your short position will decrease in value by $530. As a result of this movement, your overall net gain/loss will be relatively stable (close to zero). However, as a result of the change in delta, your new delta is now.58. This means that your options are now behaving as though they represent 580 shares of the underlying stock. Therefore, you must sell an additional 48 shares of the underlying stock to maintain your “delta neutral” status. The need to adjust your short position was caused by gamma.
You must change your position repeatedly. Your trading activity will cost you commissions and spread charges. These charges accumulate. There is also the potential for an unexpected jump in price to affect your position prior to making adjustments. Delta hedging is more appropriate for experienced investors rather than novice investors. Many novice investors choose to ignore this aspect of trading and are surprised when their hedged trades lose money.
The Options Industry Council puts it plainly: options involve risk and are not suitable for all investors.
How to Use the Greeks to Manage Risk in Your Options Trades
Run this short checklist before every trade:
Delta: how many shares does your option act like?
Theta: how much does time cost you each day?
Vega: is implied volatility already high? Then buy with care.
Gamma: be careful with short options close to expiry.
Size: start small and use stops.
Options also bring leverage. A small premium controls many shares, so losses can build fast. Read our guide to leverage and margin trading before you size a trade.
Then plan your exit. Our risk management guide for futures traders covers stops and position size. The same ideas apply to options. The Greeks change every day, so check them again as the trade ages.
Frequently Asked Questions About Option Greeks and Implied Volatility
What are the 5 option Greeks?
Delta, gamma, theta, Vega and rho. Delta represents the rate at which an option’s value will change with respect to the underlying asset’s price. Gamma represents the rate at which an option’s delta will change with respect to the underlying asset’s price. Theta represents the rate at which an option’s value will decrease with respect to the passage of time. Vega represents the rate at which an option’s value will change with respect to changes in the implied volatility of the underlying asset. Rho represents the rate at which an option’s value will change with respect to changes in interest rates.
What is a good delta for an option?
The choice will depend on what you wish to achieve. A delta close to 0.50 provides a good balance between cost and return. A delta that exceeds 0.70 will act similarly to the stock itself; however, it will also be much more expensive than a lower delta option. On the other hand, if you select a delta that is less than 0.30, your cost will be significantly less, but there is also a higher probability that your option will not end up “in-the-money.”
What is the difference between implied volatility and historical volatility?
The implied volatility of an option is calculated based on its current market price, while historical volatility is measured by the actual movement in the underlying asset over some period of time.
Why do options lose value as expiration gets closer?
The time value of an option decreases with the passage of time. The amount of time remaining before the option expires will decrease. This decrease is called “theta.” Theta will increase significantly during the last few weeks prior to expiration.
Can beginners use delta hedging?
Delta hedging requires ongoing changes to your position and trading costs will be incurred. Start by understanding the Greeks and practicing them with a pen and paper.
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