how do investors interpret a stock s beta 
a beta of 1 0 for a stock means it has been as volatile as the broader market if the index moves up or down 1 so too would the stock on average betas larger than 1 0 indicate greater volatility so if the beta were 1 5 and the index moved up or down 1 the stock would have moved 1 5 on average betas less than 1 0 indicate less volatility if the stock had a beta of 0 5 it would have risen or fallen just half a percent as the index moved 1 the bottom linebeta is the second letter of the greek alphabet used to measure the volatility of a security or portfolio compared to the s p 500 which has a beta of 1 0 a beta of 1 0 shows that a stock has been as volatile as the broader market betas larger than 1 0 indicate greater volatility and betas less than 1 0 indicate less volatility 