The Beta Coefficient is a means of measuring the volatility of a security or portfolio of securities in comparison with the market as a whole. In other words, Beta is the sensitivity of a stock's returns to the returns on some market index.
Beta is calculated using regressiopn analysis.
A beta of 1 indicates that the security's price will move with the market. A beta greater than 1 indicates that the security's price will be more volatile than the market. A beta less than 1 means that it will be less volatile than the market. People thought gold stocks should have negative betas but that hasn't been true. Most new high-tech stocks have a beta greater than one, they offer a higher rate of return but they are also very risky.