I am currently trying to carry out a mean variance optimisation, with the implementation of GARCH. I'm not sure if this is going to make complete sense as my understanding of GARCH is limited.
In the past whenever I have carried out mean variance optimisation (under Markowitz) I have calculated the expected returns, created a var-covar matrix and maximised the Sharpe Ratio [(Er-rf)/St.dev^2].
Currently, instead of carrying this out as usual, a friend who works in risk management suggested that I look at GARCH models to more accurate model volatility to account for clustering.
My question is what changes do I have to make to my mean variance optimisation for this to work? Can I take the variance outputs for each asset and run the var-covar matrix as normal and then maximise sharpe or do I have to continue to make further changes for the optimisation to actually make sense? I have read in some places that to create covariance matrix's for GARCH its best to run multivariate models.
Any help would be hugely appreciated:)