You need to use the variance and covariance functions in Excel
1. Calculate the covariance of the stock returns with respect to an index
2. Calculate the variance of the index
3. Divide the first number by the second.
See the related link for a spreadsheet
Using Excel: plot the benchmark returns against the stock returns. add a linear trendline and display the equation Beta is the slope of the trendline. Examine the spreadsheet in the related link for a worked example
To calculate the portfolio beta by weighting individual stock's betas, you would multiply each stock's beta by its weight in the portfolio, and then sum up these values to get the overall portfolio beta.
calculate the effective return (mean return minus the risk free rate) divided by the beta. the excel spreadsheet in the related link has an example.
Check out these websites: http://faculty.babson.edu/academic/Beta/CalculateBeta.htm http://www.money-zine.com/Investing/Stocks/Stock-Beta-and-Volatility/
The Beta of a stock is always dynamic.
You'll need a spreadsheet like Excel. Do the following. 1) Get percentage daily returns for the stock between two dates (I suggest every day for a year). You can get this historical data from Yahoo Finance 2) Pick a benchmark index 3) Get percentage daily returns for the index between the two dates as well 4) Calculate the covariance of the stock with respect to the index and divide by the variance of the stock [the two excel functions you'll need are covariance.p() and variance.p() ] Go to the related link below for a spreadsheet to do this.
First decide what the benchmark index is (i.e the FTSE, DOW Jones, commodities index etc). Then plot the benchmark returns against the stock returns. Then add a straight line of best fit. The beta is the slope of the trendline Check out the Excel spreadsheet in the related link.
Beta measures a stock's volatility (the swings up and down in price). The market as a whole has a beta of 1.0, but each stock is determined a beta value from a history of it's stock movements. Riskiness equates to the stock losing value and high beta stocks are more prone to falling faster.
You can use the slope function on excel which takes a cell range representing the Y-Variable and another cell range representing the X-Variables. For instance the Y-Variable may be a column of excess returns for a stock and the X-Variable maybe the column of risk premia.
You can use Beta to measure market volatility because of beta is the elasticity of a stock change as a result of a change in the market. That is, Beta of a sotck is found by comparing the senstivity of a stock's return to the fluctuations in the market.Beta is found by dividing the product of the covwariances of the stock and market retun by the variance of the market.The bench marks of betas are as followed:a risk free investment such as a Tbill (that is guaranteed a return) will have a beta of 0.A portfolio with risk equivalent to the market has a beta of 1.Given those two bench mark, you can gauge at the volatility of the stock/investment by comparing its beta with those two extremes.
The beta of a firm's stock is dependent on the volatility of the stock relative to the overall market. So if the stock's volatility increased relative to the overall market, it's beta would increase as well.
beta dc= ic/ib!!