I am trying to figure out how to find the "risk free rate of return" that will update automatically with the Sharpe ratio of multiple stocks/portfolios on a daily basis in Excel or Google Sheets.
Sharpe ratio = (Mean portfolio return − Risk-free rate)/Standard deviation of portfolio return, or, S(x) = (rx - Rf) / StandDev(rx)
I am going to use the "Treasury Yield 10 Years" (TNX) while trying to find this rate. I haven't felt comfortable with anything that I have found yet. I had an add-in that will update the TNX automatically (and any other bond I would need). Any help would be appreciated.