Hi
Beta is an available function…but is the correponding Alpha available?
Using available beta function…and I can create my own custom formula for alpha (ignoring risk free): TotalReturn of stock - (TotalReturn of S&P 500)xBeta
question is then how can I can total return of S&P 500?
Thanks
I just use the ETF SPY.
Question is what is the formula for total returns of spy I can use in my custom formula for alpha?
Alpha = total returns (of stock) - beta x total returns ( of spy)
I would use 8% for the SP500 ( Or maybe 4%, or 6% 
). I think the total return for ‘the market’ is ~8% (risk premium+riskless) as the historically correct answer. At least from my studies.
Also, which Beta (that is, over what timeframe) is right? You can go to many websites and they all have different betas. You would think it would be one number but it does not seem to be. Some use the 3Y, 5Y or whatever. Plus it changes over time. And I think your market return needs to correspond to that.
I think the problem with the CAPM is what assumptions one makes.
yes I agree on the time frame for calculating beta, which I can control by the available function: BetaFunc(period, samples[, min_samples ,offset])
I would then use corresponding Total Return (let us say 52 week) to compute alpha
(why does portfolio123 provide Beta and not Alpha function ?)
My guess as to why Alpha is not calculated because it has some many variables and assumptions.
Not really, alpha and beta are both provided for screen and simulation portfolio results.
Since Alpha is a comparison of the performance of a stock or system to a benchmark over a specified timeframe, What benchmark would you compare the total return of the S&P 500 to?
Alpha is available for screens and Sims because they have a defined timeframe and benchmark for comparing the screen or Sim performance.
using etf spy as you mentioned works. using get series in close does the trick for returns for benchmark/spy (suggested by paul).
thanks