How do you calculate a Sharpe Ratio for a Real-Time Portfolio?

You need to do the following to calculate the Sharpe ratio for a "Real-Time" changing Portfolio.

First the screenshot of a Portfolio updating in "Real-Time" with Portfolio metrics and outputs.

In order to calculate the Portfolio Sharpe Ratio you have to first calculate the Variance of the Portfolio. To do this you must first calculate a Covariance Matrix like the one in the screenshot. The Covariance matrix is then used with the weights of the portfolio securities to calculate a portfolio variance using matrix math. Once you have the portfolio variance then take the SQRT of the variance to get the portfolio volatility.

Now that you have the portfolio volatility, which can be seen as one of the outputs in the screenshot, you then can solve for the Portfolio Sharpe Ratio both ex-ante and ex-post. These are also in the screenshot outputs. All of these outputs dynamically change as the prices of the underlying securities change in real-time.

Cheers.