Beta
A multiplier that measures the movement of an investment in relation to a movement of a benchmark. For example, if an investment has a beta of 1, then the investment will move in parallel to the index as any number times 1 is that number. However, if the beta is 1.5 and the index moves by 10%, then the investment should be expected to move by 15% as 10% times 1.5 is 15%.