
Python for Finance

Based on the normality assumption, a VaR estimation considers only the first two moments: mean and variance. If stock returns truly follow a normal distribution, those two moments would fully define their probability distribution. From the preceding sections, we know that this is not true. The first remedy is to include other higher moments in addition to the first two moments. The third and fourth moments are called skewness and kurtosis. For a stock or portfolio with n returns, skewness is estimated by the following formula:
Here, skewness is the skewness, Ri is the ith return, is the mean return, n is the number of returns, and σ is the standard deviation of returns. The kurtosis reflects the impact of extreme values because a power of 4 is very high. The kurtosis is usually estimated by the following formula is:
For a standard moral distribution, it has a zero mean, unit variance, zero skewness, and its kurtosis is 3. Because of this, sometimes kurtosis is...
Change the font size
Change margin width
Change background colour