# Beta Equation (Stocks)

The beta of a stock is determined as follows:

[(n) (sum of (xy)) ]-[(sum of x) (sum of y)][(n) (sum of (xx)) ]-[(sum of x) (sum of x)]

where: n = # of observations (24-60 months)x = rate of return for the S&P 500 Indexy = rate of return for the stock

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