What is Beta?

Beta measures an investment’s volatility against the market as a whole.  A Beta of 1 means that if the market gains or loses 10% the investment is also expected to gain or lose 10%.  A beta of 1.5 would mean that a movement of 10% in the market would be expected to result in a movement of 15% in the investment.  A Beta of .8 would mean that for that same 10% in market movement you would expect an 8% movement in the investment.