The Beta is a quantitative measure of the volatility of a given stock (or instrument) relative to the volatility of the market. A score greater than 1 means the stock is more volatile than the market, lower than one, less volatile. Most betas lie between 0.5 and 1.5.

Infinancials use a simple beta calculation comparing the stock to its local country index, as shown below

Betas values lying outside the range [-0.5; +2.5] will not be considered relevant and will be shown as N/A.

Values are taken weekly, using the first close price available each week for the stock in question.
Periods are defined as follows:

Short Term	last rolling 12 months
Mid Term	last rolling 24 months
Long Term	last rolling 60 months

The calculation divides the covariance of the stock return with the market return by the variance of the market return :
thus : Beta = cov(ri,rm) / var(rm)
where

stock return	ri = (stock price at time w / stock price at time (w-1))-1
market return	rm = (index at time w / index at time (w-1))-1 E(rm) = arithmetic mean of stock returns E(ri) = arithmetic mean of market returns
covariance (stock return, market return)	cov(ri,rm) = sum[(ri-E(ri))*(rm-E(rm))]/count(ri-E(ri))*count(rm-E(rm))
variance (market return)	var(rm) = sum[(rm-E(rm))^2]/count(rm-E(rm))^2