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Gamma is one of the least understood but most powerful of the options Greeks. Gamma is the variable that tracks the rate of change of Delta. If we compared Delta to the horsepower of a car than Gamma is the acceleration or rate of change of the car. How quickly can each car make use of its available horsepower? That’s Gamma.
Unfortunately, many options investors fail to recognize the effect that Gamma can exert upon the value of an option. In reality, knowing how the Delta changes can make a significant difference in the profitability of an option play.
Here’s an example:
Suppose that XYZ is currently trading for $23.00 per share. Suppose further that a glance at the options Greeks showed that the current Delta for the $20 strike price option was .96. This means that for every dollar per share the stock price rises, the $20 strike price option will increase $0.96 per share. That’s the current situation, but a quick check of the Gamma value for the $20 strike Calls is 0.04. This means that if the stock were to increase a dollar per share, the Delta would increase by 0.04, resulting in a Delta of 1.00. Once the stock price reaches the level of $24 per share, the $20 strike price options will increase dollar for dollar in value with any further increase in the value of the stock.
Now, suppose that you were faced with two different option plays. Each of the two plays have the same Delta, and each option costs the same to purchase. But suppose one of the options carried a Gamma of 0.01, and the other carried a Gamma of 0.05. All other things being equal, the option contract with the higher Gamma would generally result in a greater profit for a given period of time, when compared to the option with a lower Gamma. A higher Gamma often equates to greater acceleration in profitability with a given increase in the value of the stock.
As expiration week approaches, I think of questions that come in from our clients as well as newer traders in the business. Expiration week is an exciting time for a lot of people in the business. This is the time that every option is a weekly and theta is paramount.
Many traders find the temptation to sell out-of-the-money (OTM) options in expiration week. The temptation can come in the form of credit spreads, covered calls, or naked options (among other things). This can be a very successful strategy if you know what you’re doing. However, if you are a unaware of the risks of gamma….BEWARE!
Question: “I can sell the OTM option and get a 2% rate of return for only 3 days…the probability of it not touching is 85%…how can I go wrong?”
Answer: Gamma
If you sell an option far OTM for a small credit, it is likely that you will be right. However, when you are wrong (notice I said when and not if), it can wipe out months if not years of profits in a single day.
Let’s say you sell an option for .35. If you are right 10 months in a row, you are ahead 3.50. In one month, you can lose 10.00 if you are not careful. I’ve seen it happen more than once.
Gamma impacts option prices more and more as expiration gets closer and closer. Indeed, the closer to expiration, gamma influences an option so much that an option can appear to be worthless and minutes later an option can take on the full charecteristics of the underlying component.
Over the years many traders have devised ways to manage the risks of gamma in the days approaching expiration. The first step of managing gamma risk is to be aware of gamma. Once you have a comprehensive understanding of how gamma affects an options price, you can begin to use strategy to manage these risks.
If you have any questions about gamma or would like some ideas to hedge gamma risks in your strategies, feel free to get in touch.