Gamma is one of the more obscure Greeks, but it has important implications in analyzing option strategies. It measures the rate of change of Delta, which is how much an option price changes given a onepoint movement in the underlying asset. Delta increases or decreases along with the underlying asset price, whereas Gamma is a constant that measures the rate of change of Delta (see table below for an example of an inthemoney call option).
Stock Price 
Option Price 
Delta 
Gamma 
$51.00 
$2.95 
0.55 
0.05 
$50.00 
$2.45 
0.50 
0.05 
$49.00 
$2.00 
0.45 
0.05 
For example, suppose that two options have the same Delta value, but one option has a high Gamma and one has a low Gamma. The option with the higher Gamma will have a higher risk since an unfavorable move in the underlying stock will have an oversized impact. High Gamma values mean that the option tends to experience volatile swings, which is a bad thing for most traders looking for predictable opportunities.
How GammaÂ Impacts Strategies
A good way to think of Gamma is the measure of the stability of an optionâ€™s probability. If Delta represents the probability of being inthemoney at expiration, Gamma represents the stability of that probability over time. An option with a high Gamma and a 0.75 Delta may have less of a chance of expiring inthemoney than a low Gamma option with the same Delta.
The table below shows position Gamma signs for common option strategies:
Strategy 
Position Gamma Sign 
Long Call 
Positive 
Short Call 
Negative 
Long Put 
Positive 
Short Put 
Negative 
Long Straddle 
Positive 
Short Straddle 
Negative 
Long Strangle 
Positive 
Short Strangle 
Negative 
Put Credit Spread 
Negative 
Put Debit Spread 
Positive 
Call Credit Spread 
Negative 
Call Debit Spread 
Positive 
Call Ratio Spread 
Negative 
Put Ratio Spread 
Negative 
Put Back Spread 
Positive 
Call Back Spread 
Positive 
Calendar Spread 
Positive 
Covered Call Write 
Positive 
Covered Put Write 
Positive 
While Gamma entails a higher level of risk, itâ€™s not always a bad thing for those that are long options. Gamma accelerates profits for every $1.00 that the underlying asset price moves in a long traderâ€™s favor and decelerates losses for every $1.00 that the underlying asset price moves against them. In essence, every dollar that the underlying asset price increases results in increasingly efficient returns on the traderâ€™s capital.Â
The Bottom Line
Gamma tells us how fast Delta changes when the underlying asset price moves. Itâ€™s most helpful for seeing the stability of an optionâ€™s probability of reaching its strike price before expiration. Higher Gammas tend to be riskier than lower gammas even if the Delta remains the same.
Options Greeks: Position Greeks

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