I want to calculate the beta of a computer vendor using return data from 31st Jan 2008 to 31 Jan 2013 (period of five years) against the return of S&P500.
I will be regressing the excess return of company against excess return of S&P500 (where the company is the dependent variable, and S&P is the independent variable).
Using the daily treasury yield curve rates as the source of my risk free rates. I am a bit dumbfounded as to exactly which rates to use.
First I have determined that I will use the five maturity constant maturity treasury rates, which is because the duration of the five year maturity treasury rates is similar to the length of the project.
but now, I don't know which date I should choose my rate from.
Should I choose the 5 year maturity on 31st Jan 2008, which is 2.82% (and divide it by 360 to get the daily rate) and use this rate for the next five years.
Or should I get the average of 5 year maturity yield from 31st Jan 2008 to 31st Jan 2013 (which is 1.8053% using excel) and use it as my risk free rate?
Or is there a better method for the estimation of the risk-free rate.